NSC800D1MIL/A - National Semiconductor

TL/C/5171

NSC800 High-Performance Low-Power CMOS Microprocessor

June 1992

NSC800TM High-Performance

Low-Power CMOS Microprocessor

General Description

The NSC800 is an 8-bit CMOS microprocessor that func-

tions as the central processing unit (CPU) in National Semi-

conductor’s NSC800 microcomputer family. National’s

microCMOS technology used to fabricate this device pro-

vides system designers with performance equivalent to

comparable NMOS products, but with the low power advan-

tage of CMOS. Some of the many system functions incorpo-

rated on the device, are vectored priority interrupts, refresh

control, power-save feature and interrupt acknowledge. The

NSC800 is available in dual-in-line and surface mounted

chip carrier packages.

The system designer can choose not only from the dedicat-

ed CMOS peripherals that allow direct interfacing to the

NSC800 but from the full line of National’s CMOS products

to allow a low-power system solution. The dedicated periph-

erals include NSC810A RAM I/O Timer, NSC858 UART,

and NSC831 I/O.

All devices are available in commercial, industrial and mili-

tary temperature ranges along with two added reliability

flows. The first is an extended burn in test and the second is

the military class C screening in accordance with Method

5004 of MIL-STD-883.

Features

YFully compatible with Z80Éinstruction set:

Powerful set of 158 instructions

10 addressing modes

22 internal registers

YLow power: 50 mW at 5V VCC

YUnique power-save feature

YMultiplexed bus structure

YSchmitt trigger input on reset

YOn-chip bus controller and clock generator

YVariable power supply 2.4Vb6.0V

YOn-chip 8-bit dynamic RAM refresh circuitry

YSpeed: 1.0 ms instruction cycle at 4.0 MHz

NSC800-4 4.0 MHz

NSC800-35 3.5 MHz

NSC800-3 2.5 MHz

NSC800-1 1.0 MHz

YCapable of addressing 64k bytes of memory and 256

I/O devices

YFive interrupt request lines on-chip

Block Diagram

TL/C/5171–73

NSC800TM is a trademark of National Semiconductor Corp.

TRI-STATEÉis a registered trademark of National Semiconductor Corp.

Z80Éis a registered trademark of Zilog Corp.

C1995 National Semiconductor Corporation RRD-B30M105/Printed in U. S. A.

Table of Contents

1.0 ABSOLUTE MAXIMUM RATINGS

2.0 OPERATING CONDITIONS

3.0 DC ELECTRICAL CHARACTERISTICS

4.0 AC ELECTRICAL CHARACTERISTICS

5.0 TIMING WAVEFORMS

NSC800 HARDWARE

6.0 PIN DESCRIPTIONS

6.1 Input Signals

6.2 Output Signals

6.3 Input/Output Signals

7.0 CONNECTION DIAGRAMS

8.0 FUNCTIONAL DESCRIPTION

8.1 Register Array

8.2 Dedicated Registers

8.2.1 Program Counter

8.2.2 Stack Pointer

8.2.3 Index Register

8.2.4 Interrupt Register

8.2.5 Refresh Register

8.3 CPU Working and Alternate Register Sets

8.3.1 CPU Working Registers

8.3.2 Alternate Registers

8.4 Register Functions

8.4.1 Accumulator

8.4.2 F RegisterÐFlags

8.4.3 Carry (C)

8.4.4 Adds/Subtract (N)

8.4.5 Parity/Overflow (P/V)

8.4.6 Half Carry (H)

8.4.7 Zero Flag (Z)

8.4.8 Sign Flag (S)

8.4.9 Additional General Purpose Registers

8.4.10 Alternate Configurations

8.5 Arithmetic Logic Unit (ALU)

8.6 Instruction Register and Decoder

9.0 TIMING AND CONTROL

9.1 Internal Clock Generator

9.2 CPU Timing

9.3 Initialization

9.4 Power Save Feature

9.0 TIMING AND CONTROL

9.5 Bus Access Control

9.6 Interrupt Control

NSC800 SOFTWARE

10.0 INTRODUCTION

11.0 ADDRESSING MODES

11.1 Register

11.2 Implied

11.3 Immediate

11.4 Immediate Extended

11.5 Direct Addressing

11.6 Register Indirect

11.7 Indexed

11.8 Relative

11.9 Modified Page Zero

11.10 Bit

12.0 INSTRUCTION SET

12.1 Instruction Set Index/Alphabetical

12.2 Instruction Set Mnemonic Notation

12.3 Assembled Object Code Notation

12.4 8-Bit Loads

12.5 16-Bit Loads

12.6 8-Bit Arithmetic

12.7 16-Bit Arithmetic

12.8 Bit Set, Reset, and Test

12.9 Rotate and Shift

12.10 Exchanges

12.11 Memory Block Moves and Searches

12.12 Input/Output

12.13 CPU Control

12.14 Program Control

12.15 Instruction Set: Alphabetical Order

12.16 Instruction Set: Numerical Order

13.0 DATA ACQUISITION SYSTEM

14.0 NSC800M/883B MIL STD 883/CLASS C

SCREENING

15.0 BURN-IN CIRCUITS

16.0 ORDERING INFORMATION

17.0 RELIABILITY INFORMATION

1.0 Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales

Office/Distributors for availability and specifications.

Storage Temperature b65§Ctoa

150§C

Voltage on Any Pin

with Respect to Ground b0.3V to VCC a0.3V

Maximum VCC 7V

Power Dissipation 1W

Lead Temp. (Soldering, 10 seconds) 300§C

2.0 Operating Conditions

NSC800-1

TAe0§Ctoa

70§C

TAeb

40§Ctoa

85§C

NSC800-3

TAe0§Ctoa

70§C

TAeb

40§Ctoa

85§C

TAeb

55§Ctoa

125§C

NSC800-35/883C

TAeb

55§Ctoa

125§C

NSC800-4

TAe0§Ctoa

70§C

TAeb

40§Ctoa

85§C

NSC800-4MIL

TAeb

55§Ctoa

90§C

3.0 DC Electrical Characteristics VCC e5V g10%, GND e0V, unless otherwise specified.

Symbol Parameter Conditions Min Typ Max Units

VIH Logical 1 Input Voltage 0.8 VCC VCC V

VIL Logical 0 Input Voltage 0 0.2 VCC V

VHY Hysteresis at RESET IN input VCC e5V 0.25 0.5 V

VOH1 Logical 1 Output Voltage IOUT eb

1.0 mA 2.4 V

VOH2 Logical 1 Output Voltage IOUT eb

10 mAV

CC b0.5 V

VOL1 Logical 0 Output Voltage IOUT e2 mA 0 0.4 V

VOL2 Logical 0 Output Voltage IOUT e10 mA 0 0.1 V

IIL Input Leakage Current 0 sVIN sVCC b10.0 10.0 mA

IOL Output Leakage Current 0 sVIN sVCC b10.0 10.0 mA

ICC Active Supply Current IOUT e0, f(XIN) e2 MHz, TAe25§C 8 11 mA

ICC Active Supply Current IOUT e0, f(XIN) e5 MHz, TAe25§C1015mA

CC Active Supply Current IOUT e0, f(XIN) e7 MHz, 15 21 mA

TAe25§C

ICC Active Supply Current IOUT e0, f(XIN) e8 MHz, TAe25§C1521mA

Quiescent Current IOUT e0, PS e0, VIN e0orV

IN eVCC 25mA

(XIN) e0 MHz, TAe25§C, XIN e0, CLK e1

IPS Power-Save Current IOUT e0, PS e0, VIN e0orV

IN eVCC 57mA

(XIN) e5.0 MHz , TAe25§

CIN Input Capacitance 610pF

OUT Output Capacitance 812pF

CC Power Supply Voltage (Note 2) 2.4 5 6 V

Note 1: Absolute Maximum Ratings indicate limits beyond which permanent damage may occur. Continuous operation at these limits is not intended and should be

limited to those conditions specified under DC Electrical Characteristics.

Note 2: CPU operation at lower voltages will reduce the maximum operating speed. Operation at voltages other than 5V g10% is guaranteed by design, not

tested.

4.0 AC Electrical Characteristics VCC e5V g10%, GND e0V, unless otherwise specified

Symbol Parameter NSC800-1 NSC800-3 NSC800-35 NSC800-4 Units Notes

Min Max Min Max Min Max Min Max

tXPeriod at XIN and XOUT 500 3333 200 3333 142 3333 125 3333 ns

Pins

T Period at Clock Output 1000 6667 400 6667 284 6667 250 6667 ns

(e2t

)

RClock Rise Time 110 110 90 80 ns Measured from

10%– 90% of signal

tFClock Fall Time 70 60 55 50 ns Measured from

10%– 90% of signal

tLClock Low Time 435 150 90 80 ns 50% duty cycle, square

wave input on XIN

tHClock High Time 450 145 85 75 ns 50% duty cycle, square

wave input on XIN

tACC(OP) ALE to Valid Data 1340 490 340 300 ns Add t for each WAIT STATE

tACC(MR) ALE to Valid Data 1875 620 405 360 ns Add t for each WAIT STATE

tAFR AD(0– 7) Float after 0 0 0 0 ns

RD Falling

tBABE BACK Rising to Bus 1000 400 300 250 ns

Enable

tBABF BACK Falling to 50 50 50 50 ns

Bus Float

tBACL BACK Fall to CLK 425 125 60 55 ns

Falling

tBRH BREQ Hold Time 0 0 0 0 ns

tBRS BREQ Set-Up Time 100 50 50 45 ns

tCAF Clock Falling ALE 0 70 0 65 0 60 0 55 ns

Falling

tCAR Clock Rising to ALE 0 100 0 100 0 90 0 80 ns

Rising

tCRD Clock Rising to 100 90 90 80 ns

Read Rising

tCRF Clock Rising to 80 70 70 65 ns

Refresh Falling

tDAI ALE Falling to INTA 445 160 95 85 ns

Falling

tDAR ALE Falling to 400 575 160 250 100 180 90 160 ns

RD Falling

tDAW ALE Falling to 900 1010 350 420 225 300 200 265 ns

WR Falling

tD(BACK)1 ALE Falling to BACK 2460 975 635 560 ns Add t for each WAIT state

Falling Add t for opcode fetch cycles

tD(BACK)2 BREQ Rising to BACK 500 1610 200 700 140 540 125 475 ns

Rising

tD(I) ALE Falling to INTR, 1360 475 284 250 ns Add t for each WAIT state

NMI, RSTA-C,PS, Add t for opcode fetch cycles

BREQ, Inputs Valid

tDPA Rising PS to 500 1685 200 760 140 580 125 510 ns See

Figure 14

also

Falling ALE

tD(WAIT) ALE Falling to 550 250 170 125 ns

WAIT Input Valid

OPÐ Opcode Fetch

MRÐ Memory Read

4.0 AC Electrical Characteristics VCC e5V g10%, GND e0V, unless otherwise specified (Continued)

Symbol Parameter NSC800-1 NSC800-3 NSC800-35 NSC800-4 Units Notes

Min Max Min Max Min Max Min Max

TH(ADH)1 A(8– 15) Hold Time During 0 0 0 0 ns

Opcode Fetch

TH(ADH)2 A(8– 15) Hold Time During 400 100 85 60 ns

Memory or IO, RD and WR

TH(ADL) AD(0– 7) Hold Time 100 60 35 30 ns

TH(WD) Write Data Hold Time 400 100 85 75 ns

tINH Interrupt Hold Time 0 0 0 0 ns

tINS Interrupt Set-Up Time 100 50 50 45 ns

tNMI Width of NMI Input 50 30 25 20 ns

tRDH Data Hold after Read 0 0 0 0 ns

tRFLF RFSH Rising to ALE 60 50 45 40 ns

Falling

tRL(MR) RD Rising to ALE Rising 390 100 50 45 ns

(Memory Read)

tS(AD) AD(0– 7) Set-Up Time 300 45 45 40 ns

tS(ALE) A(8– 15), SO, SI, IO/M 350 70 55 50 ns

Set-Up Time

tS(WD) Write Data Set-Up Time 385 75 35 30 ns

tW(ALE) ALE Width 430 130 115 100 ns

tWH WAIT Hold Time 0 0 0 0 ns

tW(I) Width of INTR, RSTA-C, 500 200 140 125 ns

PS, BREQ

tW(INTA) INTA Strobe Width 1000 400 225 200 ns Add two t states for first

INTA of each interrupt

response string Add t for

each WAIT state

tWL WR Rising to ALE Rising 450 130 70 70 ns

tW(RD) Read Strobe Width During 960 360 210 185 ns Add t for each WAIT

State Add t/2 for Memory

Opcode Fetch

Read Cycles

tW(RFSH) Refresh Strobe Width 1925 725 450 395 ns

tWS WAIT Set-Up Time 100 70 60 55 ns

tW(WAIT) WAIT Input Width 550 250 195 175 ns

tW(WR) Write Strobe Width 985 370 250 220 ns Add t for each WAIT state

tXCF XIN to Clock Falling 25 100 15 95 5 90 5 80 ns

tXCR XIN to Clock Rising 25 85 15 85 5 90 5 80 ns

Note 1: Test conditions: t e1000 ns for NSC800-1, 400 ns for NSC800, 285 ns for NSC800-35, 250 ns for NSC800-4.

Note 2: Output timings are measured with a purely capacitive load of 100 pF.

5.0 Timing Waveforms

Opcode Fetch Cycle

TL/C/5171–3

Memory Read and Write Cycle

TL/C/5171–4

5.0 Timing Waveforms (Continued)

InterruptÐPower-Save Cycle

TL/C/5171–5

Note 1: This t state is the last t state of the last M cycle of any instruction.

Note 2: Response to INTR input.

Note 3: Response to PS input.

Bus Acknowledge Cycle

TL/C/5171–6

*Waveform not drawn to proportion. Use only for specifying test points.

AC Testing Input/Output Waveform

TL/C/5171–7

AC Testing Load Circuit

TL/C/5171–8

NSC800 HARDWARE

6.0 Pin Descriptions

6.1 INPUT SIGNALS

Reset Input (RESET IN): Active low. Sets A (8– 15) and AD

(0– 7) to TRI-STATEÉ(high impedance). Clears the con-

tents of PC, I and R registers, disables interrupts, and acti-

vates reset out.

Bus Request (BREQ): Active low. Used when another de-

vice requests the system bus. The NSC800 recognizes

BREQ at the end of the current machine cycle, and sets

A(8– 15), AD(0– 7), IO/M,RD, and WR to the high imped-

ance state. RFSH is high during a bus request cycle. The

CPU acknowledges the bus request via the BACK output

signal.

Non-Maskable Interrupt (NMI): Active low. The non-mask-

able interrupt, generated by the peripheral device(s), is the

highest priority interrupt. The edge sensitive interrupt re-

quires only a pulse to set an internal flip-flop which gener-

ates the internal interrupt request. The NMI flip-flop is moni-

tored on the same clock edge as the other interrupts. It

must also meet the minimum set-up time spec for the inter-

rupt to be accepted in the current machine instruction.

When the processor accepts the interrupt the flip-flop resets

automatically. Interrupt execution is independent of the in-

terrupt enable flip-flop. NMI execution results in saving the

PC on the stack and automatic branching to restart address

X’0066 in memory.

Restart Interrupts, A, B, C (RSTA, RSTB, RSTC): Active

low level sensitive. The CPU recognizes restarts generated

by the peripherals at the end of the current instruction, if

their respective interrupt enable and master enable bits are

set. Execution is identical to NMI except the interrupts vec-

tor to the following restart addresses:

Name Restart

Address (X’)

NMI 0066

RSTA 003C

RSTB 0034

RSTC 002C

INTR (Mode 1) 0038

The order of priority is fixed. The list above starts with the

highest priority.

Interrupt Request (INTR): Active low, level sensitive. The

CPU recognizes an interrupt request at the end of the cur-

rent instruction provided that the interrupt enable and mas-

ter interrupt enable bits are set. INTR is the lowest priority

interrupt. Program control selects one of three response

modes which determines the method of servicing INTR in

conjunction with INTA. See Interrupt Control.

Wait (WAIT): Active low. When set low during RD,WRor

INTA machine cycles (during the WR machine cycle, wait

must be valid prior to write going active) the CPU extends its

machine cycle in increments of t (wait) states. The wait ma-

chine cycle continues until the WAIT input returns high.

The wait strobe input will be accepted only during machine

cycles that have RD,WRor INTA strobes and during the

machine cycle immediately after an interrupt has been ac-

cepted by the CPU. The later cycle has its RD strobe sup-

pressed but it will still accept the wait.

Power-Save (PS): Active low. PS is sampled during the last

t state of the current instruction cycle. When PS is low, the

CPU stops executing at the end of current instruction and

keeps itself in the low-power mode. Normal operation re-

sumes when PS returns high (see Power Save Feature de-

scription).

CRYSTAL (XIN,X

OUT): XIN can be used as an external

clock input. A crystal can be connected across XIN and

XOUT to provide a source for the system clock.

6.2 OUTPUT SIGNALS

Bus Acknowledge (BACK): Active low. BACK indicates to

the bus requesting device that the CPU bus and its control

signals are in the TRI-STATE mode. The requesting device

then commands the bus and its control signals.

Address Bits 8– 15 [A(8– 15)]:Active high. These are the

most significant 8 bits of the memory address during a

memory instruction. During an I/O instruction, the port ad-

dress on the lower 8 address bits gets duplicated onto A(8–

15). During a BREQ/BACK cycle, the A(8– 15) bus is in the

TRI-STATE mode.

Reset Out (RESET OUT): Active high. When RESET OUT

is high, it indicates the CPU is being reset. This signal is

normally used to reset the peripheral devices.

Input/Output/Memory (IO/M): An active high on the IO/M

output signifies that the current machine cycle is an input/

output cycle. An active low on the IO/M output signifies that

the current machine cycle is a memory cycle. It is TRI-

STATE during BREQ/BACK cycles.

Refresh (RFSH): Active low. The refresh output indicates

that the dynamic RAM refresh cycle is in progress. RFSH

goes low during T3 and T4 states of all M1 cycles. During

the refresh cycle, AD(0– 7) has the refresh address and

A(8– 15) indicates the interrupt vector register data. RFSH is

high during BREQ/BACK cycles.

Address Latch Enable (ALE): Active high. ALE is active

only during the T1 state of any M cycle and also T3 state of

the M1 cycle. The high to low transition of ALE indicates

that a valid memory, I/O or refresh address is available on

the AD(0– 7) lines.

Read Strobe (RD): Active low. The CPU receives data via

the AD(0– 7) lines on the trailing edge of the RD strobe. The

RD line is in the TRI-STATE mode during BREQ/BACK cy-

cles.

Write Strobe (WR): Active low. The CPU sends data via the

AD(0– 7) lines while the WR strobe is low. The WR line is in

the TRI-STATE mode during BREQ/BACK cycles.

Clock (CLK): CLK is the output provided for use as a sys-

tem clock. The CLK output is a square wave at one half the

input frequency.

Interrupt Acknowledge (INTA): Active low. This signal

strobes the interrupt response vector from the interrupting

peripheral devices onto the AD(0– 7) lines. INTA is active

during the M1 cycle immediately following the t state where

the CPU recognized the INTR interrupt request.

Two of the three interrupt request modes use INTA.In

mode 0 one to four INTA signals strobe a one to four byte

instruction onto the AD(0– 7) lines. In mode 2 one INTA sig-

nal strobes the lower byte of an interrupt response vector

onto the bus. In mode 1, INTA is inactive and the CPU re-

sponse to INTR is the same as for an NMI or restart inter-

rupt.

6.0 Pin Descriptions (Continued)

Status (SO, S1): Bus status outputs provide encoded infor-

mation regarding the current M cycle as follows:

Machine Cycle Status Control

S0 S1 IO/M RD WR

Opcode Fetch 1 1 0 0 1

Memory Read 0 1 0 0 1

Memory Write 1 0 0 1 0

I/O Read 0 1 1 0 1

I/O Write 1 0 1 1 0

Halt*00 0 0 1

Internal Operation*01 0 1 1

Acknowledge of Int** 11 0 1 1

*ALE is not suppressed in this cycle.

**This is the cycle that occurs immediately after the CPU accepts an inter-

rupt (RSTA, RSTB, RSTC, INTR, NMI).

Note 1: During halt, CPU continues to do dummy opcode fetch from location

following the halt instruction with a halt status. This is so CPU can continue

to do its dynamic RAM refresh.

Note 2: No early status is provided for interrupt or hardware restarts.

6.3 INPUT/OUTPUT SIGNALS

Multiplexed Address/Data [AD(0– 7)]: Active high

At RD Time: Input data to CPU.

At WR Time: Output data from CPU.

At Falling Edge Least significant byte of address

of ALE Time: during memory reference cycle. 8-bit

port address during I/O reference

cycle.

During BREQ/ High impedance.

BACK Cycle:

7.0 Connection Diagrams

Dual-In-Line Package

Top View TL/C/5171 – 10

Order Number NSC800D or N

See NS Package D40C or N40A

Chip Carrier Package

Top View TL/C/5171 – 11

Order Number NSC800E or V

See NS Package E44B or V44A

8.0 Functional Description

This section reviews the CPU architecture shown below, fo-

cusing on the functional aspects from a hardware perspec-

tive, including timing details.

As illustrated in

Figure 1

, the NSC800 is an 8-bit parallel

device. The major functional blocks are: the ALU, register

array, interrupt control, timing and control logic. These areas

are connected via the 8-bit internal data bus. Detailed de-

scriptions of these blocks ae provided in the following sec-

tions.

TL/C/5171–9

Note: Applicable pinout for 40-pin

dual-in-line package within parentheses

FIGURE 1. NSC800 CPU Functional Block Diagram

8.0 Functional Description (Continued)

8.1 REGISTER ARRAY

The NSC800 register array is divided into two parts: the

dedicated registers and the working registers, as shown in

Figure 2

Main Reg. Set Alternate Reg. Set

V â WV â W

Accumulator Flags Accumulator Flags

AFA

BCB

Working

DED

Registers

HLH

Interrupt Memory

Vector I Refresh R

Index Register IX Dedicated

Index Register IY Registers

Stack Pointer SP

Program Counter PC –

FIGURE 2. NSC800 Register Array

8.2 DEDICATED REGISTERS

There are 6 dedicated registers in the NSC800: two 8-bit

and four 16-bit registers (see

Figure 3

Although their contents are under program control, the pro-

gram has no control over their operational functions, unlike

the CPU working registers. The function of each dedicated

CPU Dedicated Registers

Program Counter PC (16)

Stack Pointer SP (16)

Index Register IX (16)

Index Register IY (16)

Interrupt Vector Register I (8)

Memory Refresh Register R (8)

FIGURE 3. Dedicated Registers

8.2.1 Program Counter (PC)

The program counter contains the 16-bit address of the cur-

rent instruction being fetched from memory. The PC incre-

ments after its contents have been transferred to the ad-

dress lines. When a program jump occurs, the PC receives

the new address which overrides the incrementer.

There are many conditional and unconditional jumps, calls,

and return instructions in the NSC800’s instruction reper-

toire that allow easy manipulation of this register in control-

ling the program execution (i.e. JP NZ nn, JR Zd2, CALL

NC, nn).

8.2.2 Stack Pointer (SP)

The 16-bit stack pointer contains the address of the current

top of stack that is located in external system RAM. The

stack is organized in a last-in, first-out (LIFO) structure. The

pointer decrements before data is pushed onto the stack,

and increments after data is popped from the stack.

Various operations store or retrieve, data on the stack. This,

along with the usage of subroutine calls and interrupts, al-

lows simple implementation of subroutine and interrupt

nesting as well as alleviating many problems of data manip-

ulation.

8.2.3 Index Register (IX and IY)

The NSC800 contains two index registers to hold indepen-

dent, 16-bit base addresses used in the indexed addressing

mode. In this mode, an index register, either IX or IY, con-

tains a base address of an area in memory making it a point-

er for data tables.

In all instructions employing indexed modes of operation,

another byte acts as a signed two’s complement displace-

ment. This addressing mode enables easy data table ma-

nipulations.

8.2.4 Interrupt Register (I)

When the NSC800 provides a Mode 2 response to INTR,

the action taken is an indirect call to the memory location

containing the service routine address. The pointer to the

address of the service routine is formed by two bytes, the

high-byte is from the I Register and the low-byte is from the

interrupting peripheral. The peripheral always provides an

even address for the lower byte (LSBe0). When the proc-

essor receives the lower byte from the peripheral it concate-

nates it in the following manner:

I Register External byte

8 bits 0

The LSB of the external byte must be zero.

FIGURE 4a. Interrupt Register

The even memory location contains the low-order byte, the

next consecutive location contains the high-order byte of

the pointer to the beginning address of the interrupt service

routine.

8.2.5 Refresh Register (R)

For systems that use dynamic memories rather than static

RAM’s, the NSC800 provides an integral 8-bit memory re-

fresh counter. The contents of the register are incremented

after each opcode fetch and are sent out on the lower por-

tion of the address bus, along with a refresh control signal.

This provides a totally transparent refresh cycle and does

not slow down CPU operation.

The program can read and write to the R register, although

this is usually done only for test purposes.

8.0 Functional Description (Continued)

8.3 CPU WORKING AND ALTERNATE REGISTER SETS

8.3.1 CPU Working Registers

The portion of the register array shown in

Figure 4b

repre-

sents the CPU working registers. These sixteen 8-bit regis-

ters are general-purpose registers because they perform a

multitude of functions, depending on the instruction being

executed. They are grouped together also due to the types

of instructions that use them, particularly alternate set oper-

ations.

The F (flag) register is a special-purpose register because

its contents are more a result of machine status rather than

program data. The F register is included because of its inter-

action with the A register, and its manipulations in the alter-

nate register set operations.

8.3.2 Alternate Registers

The NSC800 registers designated as CPU working registers

have one common feature: the existence of a duplicate reg-

ister in an alternate register set. This architectural concept

simplifies programming during operations such as interrupt

response, when the machine status represented by the con-

tents of the registers must be saved.

The alternate register concept makes one set of registers

available to the programmer at any given time. Two instruc-

tions (EX AF, A‘F’ and EXX), exchange the current working

set of registers with their alternate set. One exchange be-

tween the A and F registers and their respective duplicates

(A’ and F’) saves the primary status information contained in

the accumulator and the flag register. The second exchange

instruction performs the exchange between the remaining

registers, B, C, D, E, H, and L, and their respective alter-

nates B’, C’, D’, E’, H’, and L’. This essentially saves the

contents of the original complement of registers while pro-

viding the programmer with a usable alternate set.

CPU Main Working Register Set

Accumulator A (8) Flags F (8)

CPU Alternate Working Register Set

Accumulator A’ (8) Flags F’ (8)

FIGURE 4b. CPU Working and Alternate Registers

8.4 REGISTER FUNCTIONS

8.4.1 Accumulator (A Register)

The A register serves as a source or destination register for

data manipulation instructions. In addition, it serves as the

accumulator for the results of 8-bit arithmetic and logic op-

erations.

The A register also has a special status in some types of

operations; that is, certain addressing modes are reserved

for the A register only, although the function is available for

all the other registers. For example, any register can be

loaded by immediate, register indirect, or indexed address-

ing modes. The A register, however, can also be loaded via

an additional register indirect addressing.

Another special feature of the A register is that it produces

more efficient memory coding than equivalent instruction

functions directed to other registers. Any register can be

rotated; however, while it requires a two-byte instruction to

normally rotate any register, a single-byte instruction is

available for rotating the contents of the accumulator (A reg-

ister).

8.4.2 F Register - Flags

The NSC800 flag register consists of six status bits that

contain information regarding the results of previous CPU

operations. The register can be read by pushing the con-

tents onto the stack and then reading it, however, it cannot

be written to. It is classified as a register because of its

affiliation with the accumulator and the existence of a dupli-

cate register for use in exchange instructions with the accu-

mulator.

Of the six flags shown in

Figure 5

, only four can be directly

tested by the programmer via conditional jump, call, and

return instructions. They are the Sign (S), Zero (Z), Parity/

Overflow (P/V), and Carry (C) flags. The Half Carry (H) and

Add/Subtract (N) flags are used for internal operations re-

lated to BCD arithmetic.

TL/C/5171–23

FIGURE 5. Flag Register

8.0 Functional Description (Continued)

8.4.3 Carry (C)

A carry from the highest order bit of the accumulator during

an add instruction, or a borrow generated during a subtrac-

tion instruction sets the carry flag. Specific shift and rotate

instructions also affect this bit.

Two specific instructions in the NSC800 instruction reper-

toire set (SCF) or complement (CCF) the carry flag.

Other operations that affect the C flag are as follows:

#Adds

#Subtracts

#Logic Operations (always resets C flag)

#Rotate Accumulator

#Rotate and Shifts

#Decimal Adjust

#Negation of Accumulator

Other operations do not affect the C flag.

8.4.4 Adds/Subtract (N)

This flag is used in conjunction with the H flag to ensure that

the proper BCD correction algorithm is used during the deci-

mal adjust instruction (DAA). The correction algorithm de-

pends on whether an add or subtract was previously done

with BCD operands.

The operations that set the N flag are:

#Subtractions

#Decrements (8-bit)

#Complementing of the Accumulator

#Block I/O

#Block Searches

#Negation of the Accumulator

The operations that reset the N flag are:

#Adds

#Increments

#Logic Operations

#Rotates

#Set and Complement Carry

#Input Register Indirect

#Block Transfers

#Load of the I or R Registers

#Bit Tests

Other operations do not affect the N flag.

8.4.5 Parity/Overflow (P/V)

The Parity/Overflow flag is a dual-purpose flag that indi-

cates results of logic and arithmetic operations. In logic op-

erations, the P/V flag indicates the parity of the result; the

flag is set (high) if the result is even, reset (low) if the result

is odd. In arithmetic operations, it represents an overflow

condition when the result, interpreted as signed two’s com-

plement arithmetic, is out of range for the eight-bit accumu-

lator (i.e. b128 to a127).

The following operations affect the P/V flag according to

the parity of the result of the operation:

#Logic Operations

#Rotate and Shift

#Rotate Digits

#Decimal Adjust

#Input Register Indirect

The following operations affect the P/V flag according to

the overflow result of the operation.

#Adds (16 bit with carry, 8-bit with/without carry)

#Subtracts (16 bit with carry, 8-bit with/without carry)

#Increments and Decrements

#Negation of Accumulator

The P/V flag has no significance immediately after the fol-

lowing operations.

#Block I/O

#Bit Tests

In block transfers and compares, the P/V flag indicates the

status of the BC register, always ending in the reset state

after an auto repeat of a block move. Other operations do

not affect the P/V flag.

8.4.6 Half Carry (H)

This flag indicates a BCD carry, or borrow, result from the

low-order four bits of operation. It can be used to correct the

results of a previously packed decimal add, or subtract, op-

eration by use of the Decimal Adjust Instruction (DAA).

The following operations affect the H flag:

#Adds (8-bit)

#Subtracts (8-bit)

#Increments and Decrements

#Decimal Adjust

#Negation of Accumulator

#Always Set by: Logic AND

Complement Accumulator

Bit Testing

#Always Reset By: Logic OR’s and XOR’s

Rotates and Shifts

Set Carry

Input Register Indirect

Block Transfers

Loads of I and R Registers

The H flag has no significance immediately after the follow-

ing operations.

#16-bit Adds with/without carry

#16-Bit Subtracts with carry

#Complement of the carry

#Block I/O

#Block Searches

Other operations do not affect the H flag.

8.0 Functional Description (Continued)

8.4.7 Zero Flag (Z)

Loading a zero in the accumulator or when a zero results

from an operation sets the zero flag.

The following operations affect the zero flag.

#Adds (16-bit with carry, 8-bit with/without carry)

#Subtracts (16-bit with carry, 8-bit with/without carry)

#Logic Operations

#Increments and Decrements

#Rotate and Shifts

#Rotate Digits

#Decimal Adjust

#Input Register Indirect

#Block I/O (always set after auto repeat block I/O)

#Block Searches

#Load of I and R Registers

#Bit Tests

#Negation of Accumulator

The Z flag has no signficance immediately after the follow-

ing operations:

#Block Transfers

Other operations do not affect the zero flag.

8.4.8 Sign Flag (S)

The sign flag stores the state of bit 7 (the most-signifi-

cant bit and sign bit) of the accumulator following an arith-

metic operation. This flag is of use when dealing with signed

numbers.

The sign flag is affected by the following operation accord-

ing to the result:

#Adds (16-bit with carry, 8-bit with/without carry)

#Subtracts (16-bit with carry, 8-bit with/without carry)

#Logic Operations

#Increments and Decrements

#Rotate and Shifts

#Rotate Digits

#Decimal Adjust

#Input Register Indirect

#Block Search

#Load of I and R Registers

#Negation of Accumulator

The S flag has no significance immediately after the follow-

ing operations:

#Block I/O

#Block Transfers

#Bit Tests

Other operations do not affect the sign bit.

8.4.9 Additional General-Purpose Registers

The other general-purpose registers are the B, C, D, E, H

and L registers and their alternate register set, B’, C’, D’, E’,

H’ and L’. The general-purpose registers can be used inter-

changeably.

In addition, the B and C registers perform special functions

in the NSC800 expanded I/O capabilities, particularly block

I/O operations. In these functions, the C register can ad-

dress I/O ports; the B register provides a counter function

when used in the register indirect address mode.

When used with the special condition jump instruction

(DJNZ) the B register again provides the counter function.

8.4.10 Alternate Configurations

The six 8-bit general purpose registers (B,C,D,E,H,L) will

combine to form three 16-bit registers. This occurs by con-

catenating the B and C registers to form the BC register, the

D and E registers form the DE register, and the H and L

registers form the HL register.

Having these 16-bit registers allows 16-bit data handling,

thereby expanding the number of 16-bit registers available

for memory addressing modes. The HL register typically

provides the pointer address for use in register indirect ad-

dressing of the memory.

The DE register provides a second memory pointer register

for the NSC800’s powerful block transfer operations. The

BC register also provides an assist to the block transfer

operations by acting as a byte-counter for these operations.

8.5 ARITHMETIC-LOGIC UNIT (ALU)

The arithmetic, logic and rotate instructions are performed

by the ALU. The ALU internally communicates with the reg-

isters and data buffer on the 8-bit internal data bus.

8.6 INSTRUCTION REGISTER AND DECODER

During an opcode fetch, the first byte of an instruction is

transferred from the data buffer (i.e. its on the internal data

bus) to the instruction register. The instruction register feeds

the instruction decoder, which gated by timing signals, gen-

erates the control signals that read or write data from or to

the registers, control the ALU and provide all required exter-

nal control signals.

9.0 Timing and Control

9.1 INTERNAL CLOCK GENERATOR

An inverter oscillator contained on the NSC800 chip pro-

vides all necessary timing signals. The chip operation fre-

quency is equal to one half of the frequency of this oscilla-

tor.

The oscillator frequency can be controlled by one of the

following methods:

1. Leaving the XOUT pin unterminated and driving the XIN

pin with an externally generated clock as shown in

Figure

. When driving XIN with a square wave, the minimum

duty cycle is 30% high.

TL/C/5171–13

FIGURE 6. Use of External Clock

2. Connecting a crystal with the proper biasing network be-

tween XIN and XOUT as shown in

Figure 7

. Recommend-

ed crystal is a parallel resonance AT cut crystal.

Note 1: If the crystal frequency is between 1 MHz and 2 MHz a series

resistor, RS, (470Xto 1500X) should be connected between

XOUT and R, XTAL and CZ. Additionally, the capacitance of C1

and C2 should be increased by 2 to 3 times the recommended

value. For crystal frequencies less than 1 MHz higher values of

C1 and C2 may be required. Crystal parameters will also affect

the capacitive loading requirements.

2 MHz kf(XTAL)

Re1MX

C1e20 pF

C2e34 pF

(Recommended)

TL/C/5171–14

FIGURE 7. Use Of Crystal

The CPU has a minimum clock frequency input (@XIN)of

300 kHz, which results in 150 kHz system clock speed. All

registers internal to the chip are static, however there is

dynamic logic which limits the minimum clock speed. The

input clock can be stopped without fear of losing any data or

damaging the part. You stop it in the phase of the clock that

has XIN low and CLK OUT high. When restarting the CPU,

precautions must be taken so that the input clock meets

these minimum specification. Once started, the CPU will

continue operation from the same location at which it was

stopped. During DC operation of the CPU, typical current

drain will be 2 mA. This current drain can be reduced by

placing the CPU in a wait state during an opcode fetch cycle

then stopping the clock. For clock stop circuit, see

Figure 8

TL/C/5171–36

FIGURE 8. Clock Stop Circuit

9.0 Timing and Control (Continued)

9.2 CPU TIMING

The NSC800 uses a multiplexed bus for data and address-

es. The 16-bit address bus is divided into a high-order 8-bit

address bus that handles bits 8– 15 of the address, and a

low-order 8-bit multiplexed address/data bus that handles

bits 0– 7 of the address and bits 0– 7 of the data. Strobe

outputs from the NSC800 (ALE, RD and WR) indicate when

a valid address or data is present on the bus. IO/M indi-

cates whether the ensuing cycle accesses memory or I/O.

During an input or output instruction, the CPU duplicates the

lower half of the address [AD(0–7)]onto the upper address

bus [A(8– 15)]. The eight bits of address will stay on A(8–

15) for the entire machine cycle and can be used for chip

selection directly.

Figure 9

illustrates the timing relationship for opcode fetch

cycles with and without a wait state.

TL/C/5171–15

FIGURE 9a. Opcode Fetch Cycles without WAIT States

TL/C/5171–16

FIGURE 9b. Opcode Fetch Cycles with WAIT States

9.0 Timing and Control (Continued)

During the opcode fetch, the CPU places the contents of

the PC on the address bus. The falling edge of ALE indi-

cates a valid address on the AD(0– 7) lines. The WAIT input

is sampled during t2and if active causes the NSC800 to

insert a wait state (tw). WAIT is sampled again during twso

that when it goes inactive, the CPU continues its opcode

fetch by latching in the data on the rising edge of RD from

the AD(0– 7) lines. During t3, RFSH goes active and AD(0–

7) has the dynamic RAM refresh address from register R

and A(8– 15) the interrupt vector from register I.

TL/C/5171–17

FIGURE 10a. Memory Read/Write Cycles without WAIT States

TL/C/5171–18

FIGURE 10b. Memory Read and Write with WAIT States

9.0 Timing and Control (Continued)

Figure 10

shows the timing for memory read (other than

opcode fetchs) and write cycles with and without a wait

state. The RD stobe is widened by t

2(half the machine

state) for memory reads so that the actual latching of the

input data occurs later.

Figure 11

shows the timing for input and output cycles with

and without wait states. The CPU automatically inserts one

wait state into each I/O instruction to allow sufficient time

for an I/O port to decode the address.

TL/C/5171–19

FIGURE 11a. Input and Output Cycles without WAIT States

TL/C/5171–20

*WAIT state automatically inserted during IO operation.

FIGURE 11b. Input and Output Cycles with WAIT States

9.0 Timing and Control (Continued)

9.3 INITIALIZATION

RESET IN initializes the NSC800; RESET OUT initializes the

peripheral components. The Schmitt trigger at the RESET

IN input facilitates using an R-C network reset scheme dur-

ing power up (see

Figure 12

To ensure proper power-up conditions for the NSC800, the

following power-up and initialization procedure is recom-

mended:

1. Apply power (VCC and GND) and set RESET IN active

(low). Allow sufficient time (approximately 30 ms if a crys-

tal is used) for the oscillator and internal clocks to stabi-

lize. RESET IN must remain low for at least 3t state (CLK)

times. RESET OUT goes high as soon as the active

RESET IN signal is clocked into the first flip-flop after the

on-chip Schmitt trigger. RESET OUT signal is available to

reset the peripherals.

2. Set RESET IN high. RESET OUT then goes low as the

inactive RESET IN signal is clocked into the first flip-flop

after the on-chip Schmitt trigger. Following this the CPU

initiates the first opcode fetch cycle.

Note: The NSC800 initialization includes: Clear PC to

X’0000 (the first opcode fetch, therefore, is from memory

location X’0000). Clear registers I (Interrupt Vector Base)

and R (Refresh Counter) to X’00. Clear interrupt control reg-

ister bits IEA, IEB and IEC. The interrupt control bit IEI is set

to 1 to maintain INS8080A/Z80A compatibility (see INTER-

RUPTS for more details). The CPU disables maskable inter-

rupts and enters INTR Mode 0. While RESET IN is active

(low), the A(8– 15) and AD(0– 7) lines go to high impedance

(TRI-STATE) and all CPU strobes go to the inactive state

(see

Figure 13

TL/C/5171–21

FIGURE 12. Power-On Reset

9.4 POWER-SAVE FEATURE

The NSC800 provides a unique power-save mode by the

means of the PS pin. PS input is sampled at the last t state

of the last M cycle of an instruction. After recognizing an

active (low) level on PS, The NSC800 stops its internal

clocks, thereby reducing its power dissipation to one half of

operating power, yet maintaining all register values and in-

ternal control status. The NSC800 keeps its oscillator run-

ning, and makes the CLK signal available to the system.

When in power-save the ALE strobe will be stopped high

and the address lines [AD(0–7), A(8–15)]will indicate the

next machine address. When PS returns high, the opcode

fetch (or M1 cycle) of the CPU begins in a normal manner.

Note this M1 cycle could also be an interrupt acknowledge

cycle if the NSC800 was interrupted simultaneously with PS

(i.e. PS has priority over a simultaneously occurring inter-

rupt). However, interrupts are not accepted during power

save.

Figure 14

illustrates the power save timing.

TL/C/5171–74

FIGURE 13. NSC800 Signals During Power-On and Manual Reset

9.0 Timing and Control (Continued)

TL/C/5171–28

FIGURE 14. NSC800 Power-Save

TL/C/5171–22

*S0, S1 during BREQ will indicate same machine cycle as during the cycle when BREQ was accepted.

tZetime states during which bus and control signals are in high impedance mode.

FIGURE 15. Bus Acknowledge Cycle

In the event BREQ is asserted (low) at the end of an instruc-

tion cycle and PS is active simultaneously, the following oc-

curs:

1. The NSC800 will go into BACK cycle.

2. Upon completion of BACK cycle if PS is still active the

CPU will go into power-save mode.

9.5 BUS ACCESS CONTROL

Figure 15

illustrates bus access control in the NSC800. The

external device controller produces an active BREQ signal

that requests the bus. When the CPU responds with BACK

then the bus and related control strobes go to high imped-

ance (TRI-STATE) and the RFSH signal remains high. It

should be noted that (1) BREQ is sampled at the last t state

of any M machine cycle only. (2) The NSC800 will not ac-

knowledge any interrupt/restart requests, and will not pe-

form any dynamic RAM refresh functions until after BREQ

input signal is inactive high. (3) BREQ signal has priority

over all interrupt request signals, should BREQ and interrupt

request become active simultaneously. Therefore, interrupts

latched at the end of the instruction cycle will be serviced

after a simultaneously occurring BREQ. NMI is latched dur-

ing an active BREQ.

9.6 INTERRUPT CONTROL

The NSC800 has five interrupt/restart inputs, four are mask-

able (RSTA, RSTB, RSTC, and INTR) and one is non-mask-

able (NMI). NMI has the highest priority of all interrupts; the

user cannot disable NMI. After recognizing an active input

on NMI, the CPU stops before the next instruction, pushes

the PC onto the stack, and jumps to address X’0066, where

the user’s interrupt service routine is located (i.e., restart to

memory location X’0066). NMI is intended for interrupts re-

quiring immediate attention, such as power-down, control

panel, etc.

RSTA, RSTB and RSTC are restart inputs, which, if enabled,

execute a restart to memory location X’003C, X’0034, and

X’002C, respectively. Note that the CPU response to the

NMI and RST (A,B,C) request input is basically identical,

except for the restored memory location. Unlike NMI, how-

ever, restart request inputs must be enabled.

Figure 16

illustrates NMI and RST interrupt machine cycles.

M1 cycle will be a dummy opcode fetch cycle followed by

M2 and M3 which are stack push operations. The following

instruction then starts from the interrupts restart location.

Note: RD does

not

go low during this dummy opcode fetch. A unique indica-

tion of INTA can be decoded using 2 ALEs and RD.

9.0 Timing and Control (Continued)

TL/C/5171–24

Note 1: This is the only machine cycle that does not have an RD,WR, or INTA strobe but will accept a wait strobe.

FIGURE 16. Non-Maskable and Restart Interrupt Machine Cycle

The NSC800 also provides one more general purpose inter-

rupt request input, INTR. When enabled, the CPU responds

to INTR in one of the three modes defined by instruction

IM0, IM1, and IM2 for modes 0, 1, and 2, respectively. Fol-

lowing reset, the CPU automatically enables mode 0.

Interrupt (INTR) Mode 0: The CPU responds to an interrupt

request by providing an INTA (interrupt acknowledge)

strobe, which can be used to gate an instruction from a

peripheral onto the data bus. The CPU inserts two wait

states during the first INTA cycle to allow the interrupting

device (or its controller) ample time to gate the instruction

and determine external priorities (

Figure 18

). This can be

any instruction from one to four bytes. The most popular

instruction is one-byte call (restart instruction) or a three-

byte call (CALL NN instruction). If it is a three-byte call, the

CPU issues a total of three INTA strobes. The last two

(which do not include wait states) read NN.

Note: If the instruction stored in the ICU doesn’t require the PC to be

pushed onto the stack (eq. JP nn), then the PC will not be pushed.

Interrupt (INTR) Mode 1: Similar to restart interrupts ex-

cept the restart location is X’0038 (

Figure 18

Interrupt (INTR) Mode 2: With this mode, the programmer

maintains a table that contains the 16-bit starting address of

every interrupt service routine. This table can be located

anywhere in memory. When the CPU accepts a Mode 2

interrupt (

Figure 17

), it forms a 16-bit pointer to obtain the

desired interrupt service routine starting address from the

table. The upper 8 bits of this pointer are from the contents

of the I register. The lower 8 bits of the pointer are supplied

by the interrupting device with the LSB forced to zero. The

programmer must load the interrupt vector prior to the inter-

rupt occurring. The CPU uses the pointer to get the two

adjacent bytes from the interrupt service routine starting ad-

dress table to complete 16-bit service routine starting ad-

dress. The first byte of each entry in the table is the least

significant (low-order) portion of the address. The program-

mer must obviously fill this table with the desired addresses

before any interrupts are to be accepted.

Note that the programmer can change this table at any time

to allow peripherals to be serviced by different service rou-

tines. Once the interrupting device supplies the lower por-

tion of the pointer, the CPU automatically pushes the pro-

gram counter onto the stack, obtains the starting address

from the table and does a jump to this address.

The interrupts have fixed priorities built into the NSC800 as:

NMI 0066 (Highest Priority)

RSTA 003C

RSTB 0034

RSTC 002C

INTR 0038 (Lowest Priority)

Interrupt Enable, Interrupt Disable. The NSC800 has two

types of interrupt inputs, a non-maskable interrupt and four

software maskable interrupts. The non-maskable interrupt

(NMI) cannot be disabled by the programmer and will be

accepted whenever a peripheral device requests an inter-

rupt. The NMI is usually reserved for important functions

that must be serviced when they occur, such as imminent

power failure. The programmer can selectively enable or

disable maskable interrupts (INT, RSTA, RSTB and RSTC).

This selectivity allows the programmer to disable the mask-

able interrupts during periods when timing constraints don’t

allow program interruption.

There are two interrupt enable flip-flops (IFF1and IFF2)on

the NSC800. Two instructions control these flip-flops. En-

able Interrupt (EI) and Disable Interrupt (DI). The state of

IFF1determines the enabling or disabling of the maskable

interrupts, while IFF2is used as a temporary storage loca-

tion for the state of IFF1.

9.0 Timing and Control (Continued)

A reset to the CPU will force both IFF1and IFF2to the reset

state disabling maskable interrupts. They can be enabled by

an EI instruction at any time by the programmer. When an EI

instruction is executed, any pending interrupt requests will

not be accepted until after the instruction following EI has

been executed. This single instruction delay is necessary in

situations where the following instruction is a return instruc-

tion and interrupts must not be allowed until the return has

been completed. The EI instruction sets both IFF1and IFF2

to the enable state. When the CPU accepts an interrupt,

both IFF1and IFF2are automatically reset, inhibiting further

interrupts until the programmer wishes to issue a new EI

instruction. Note that for all the previous cases, IFF1and

IFF2are always equal.

The function of IFF2is to retain the status of IFF1when a

non-maskable interrupt occurs. When a non-maskable inter-

rupt is accepted, IFF1is reset to prevent further interrupts

until reenabled by the programmer. Thus, after a non-mask-

able interrupt has been accepted, maskable interrupts are

disabled but the previous state of IFF1is saved by IFF2

TL/C/5171–27

FIGURE 17. Interrupt Mode 2

9.0 Timing and Control (Continued)

TL/C/5171–25

*tWis the CPU generated WAIT state in response to an interrupt request.

Note 1: t5 will only occur in mode 1 and mode 2. During t5 the stack pointer is decremented.

Note 2: A jump to the appropriate address occurs here in mode 1 and mode 2. The CPU continues gathering data from the interrupting peripheral in mode 0 for a total of 2–4

machine cycles. In mode 0 cycles M2–M4 have only 1 wait state.

FIGURE 18. Interrupt Acknowledge Machine Cycle

9.0 Timing and Control (Continued)

so that the complete state of the CPU just prior to the non-

maskable interrupt may be restored. The method of restor-

ing the status of IFF1is through the execution of a Return

Non-Maskable Interrupt (RETN) instruction. Since this in-

struction indicates that the non-maskable interrupt service

routine is completed, the contents of IFF2are now copied

back into IFF1, so that the status of IFF1just prior to the

acceptance of the non-maskable interrupt will be automati-

cally restored.

Figure 19

depicts the status of the flip flops during a sample

series of interrupt instructions.

Interrupt Control Register. The interrupt control register

(ICR) is a 4-bit, write only register that provides the program-

mer with a second level of maskable control over the four

maskable interrupt inputs.

The ICR is internal to the NSC800 CPU, but is addressed

through the I/O space at I/O address port X’BB. Each bit in

the register controls a mask bit dedicated to each maskable

interrupt, RSTA, RSTB, RSTC and INTR. For an interrupt

request to be accepted on any of these inputs, the corre-

sponding mask bit in the ICR must be set (e1) and IFF1

and IFF2must be set. This provides the programmer with

control over individual interrupt inputs rather than just a sys-

tem wide enable or disable.

TL/C/5171–26

Bit Name Function

0 IEI Interrupt Enable for INTR

1 IEC Interrupt Enable for RSTC

2 IEB Interrupt Enable for RSTB

3 IEA Interrupt Enable for RSTA

For example: In order to enable RSTB, CPU interrupts must

be enabled and IEB must be set.

At reset, IEI bit is set and other mask bits IEA, IEB, IEC are

cleared. This maintains the software compatibility between

NSC800 and Z80A.

Execution of an I/O block move instruction will not affect

the state of the interrupt control bits. The only two instruc-

tions that will modify this write only register are OUT (C), r

and OUT (N), A.

Operation IFF1IFF2Comment

Initialize 0 0 Interrupt Disabled

EI 1 1 Interrupt Enabled after

#next instruction

INTR 0 0 Interrupt Disable and INTR

Being Serviced

EI 1 1 Interrupt Enabled after

next instruction

RET 1 1 Interrupt Enabled

NMI 0 1 Interrupt Disabled

RETN 1 1 Interrupt Enabled

INTR 0 0 Interrupt Disabled

NMI 0 0 Interrupt Disabled and NMI

#Being Serviced

RETN 0 0 Interrupt Disabled and INTR

#Being Serviced

EI 1 1 Interrupt Enabled after

next instruction

RET 1 1 Interrupt Enabled

FIGURE 19. IFF1and IFF2States Immediately after the

Operation has been Completed

NSC800 SOFTWARE

10.0 Introduction

This chapter provides the reader with a detailed description

of the NSC800 software. Each NSC800 instruction is de-

scribed in terms of opcode, function, flags affected, timing,

and addressing mode.

11.0 Addressing Modes

The following sections describe the addressing modes sup-

ported by the NSC800. Note that particular addressing

modes are often restricted to certain types of instructions.

Examples of instructions used in the particular addressing

modes follow each mode description.

The 10 addressing modes and 158 instructions provide a

flexible and powerful instruction set.

11.1 REGISTER

The most basic addressing mode is that which addresses

data in the various CPU registers. In these cases, bits in the

opcode select specific registers that are to be addressed by

the instruction.

Example:

Instruction: Load register B from register C

Mnemonic: LD B,C

Opcode:

TL/C/5171–50

In this instruction, both the B and C registers are addressed

by opcode bits.

11.2 IMPLIED

The implied addressing mode is an extension to the register

addressing mode. In this mode, a specific register, the accu-

mulator, is used in the execution of the instruction. In partic-

ular, arithmetic operations employ implied addressing, since

the A register is assumed to be the destination register for

the result without being specifically referenced in the op-

code.

Example:

Instruction: Subtract the contents of register D from the

Accumulator (A register)

Mnemonic: SUB D

Opcode:

TL/C/5171–51

In this instruction, the D register is addressed with register

addressing, while the use of the A register is implied by the

opcode.

11.3 IMMEDIATE

The most straightforward way of introducing data to the

CPU registers is via immediate addressing, where the data

is contained in an additional byte of multi-byte instructions.

Example:

Instruction: Load the E register with the constant value

X’7C.

Mnemonic: LD E,X’7C

Opcode:

TL/C/5171–52

In this instruction, the E register is addressed with register

addressing, while the constant X’7C is immediate data in the

second byte of the instruction.

11.4 IMMEDIATE EXTENDED

As immediate addressing allows 8 bits of data to be sup-

plied by the operand, immediate extended addressing al-

lows 16 bits of data to be supplied by the operand. These

are in two additional bytes of the instruction.

Example:

Instruction: Load the 16-bit IX register with the constant

value X’ABCD.

Mnemonic: LD IX,X’ABCD

Opcode:

TL/C/5171–53

In this instruction, register addressing selects the IX regis-

ter, while the 16-bit quanity X’ABCD is immediate data sup-

plied as immediate extended format.

11.0 Addressing Modes (Continued)

11.5 DIRECT ADDRESSING

Direct addressing is the most straightforward way of ad-

dressing supplies a location in the memory space. Direct

addressing, 16-bits of memory address information in two

bytes of data as part of the instruction. The memory address

could be either data, source of destination, or a location for

program execution, as in program control instructions.

Example:

Instruction: Jump to location X’0377

Mnemonic: JP X’0377

Opcode:

11000011 ÐDefines jump opcode

01110111 ÐConstant X’0377

00000011(

This instruction loads the Program Counter (PC) is loaded

with the constant in the second and third bytes of the in-

struction. The program counter contents are transferred via

direct addressing.

11.6 REGISTER INDIRECT

Next to direct addressing, register indirect addressing pro-

vides the second most straightforward means of addressing

memory. In register indirect addressing, a specified register

pair contains the address of the desired memory location.

The instruction references the register pair and the register

contents define the memory location of the operand.

Example:

Instruction: Add the contents of memory location X’0254 to

the A register. The HL register contains X’0254.

Mnemonic: ADD A,(HL)

Opcode

10000110

This instruction uses implied addressing of the A and HL

registers and register indirect addressing to access the data

pointed to by the HL register.

11.7 INDEXED

The most flexible mode of memory addressing is the in-

dexed mode. This is similar to the register indirect mode of

addressing because one of the two index registers (IX or IY)

contains the base memory address. In addition, a byte of

data included in the instruction acts as a displacement to

the address in the index register.

Indexed addressing is particularly useful in dealing with lists

of data.

Example:

Instruction: Increment the data in memory location X’1020.

The IY register contains X’1000.

Mnemonic: INC (IYaX’20)

Opcode:

TL/C/5171–54

The indexed addressing mode uses the contents of index

registers IX or IY along with the displacement to form a

pointer to memory.

11.8 RELATIVE

Certain instructions allow memory locations to be ad-

dressed as a position relative to the PC register. These in-

structions allow jumps to memory locations which are off-

sets around the program counter. The offset, together with

the current program location, is determined through a dis-

placement byte included in the instruction. The formation of

this displacement byte is explained more fully in the ‘‘In-

structions Set’’ section.

Example:

Instruction: Jump to a memory location 7 bytes beyond the

current location.

Mnemonic: JR $a7

Opcode:

00011000ÐDefines relative jump

opcode

00000101ÐDisplacement to be

applied to the PC

The program will continue at a location seven locations past

the current PC.

11.0 Addressing Modes (Continued)

11.9 MODIFIED PAGE ZERO

A subset of NSC800 instructions (the Restart instructions)

provides a code-efficient single-byte instruction that allows

CALLs to be performed to any one of eight dedicated loca-

tions in page zero (locations X’0000 to X’00FF). Normally, a

CALL is a 3-byte instruction employing direct memory ad-

dressing.

Example:

Instruction: Perform a restart call to location X’0028.

Mnemonic: RST X’28

Opcode:

TL/C/5171–55

p 00H 08H 10H 18H 20H 28H 30H 38H

t 000 001 010 011 100 101 110 111

Program execution continues at location X’0028 after exe-

cution of a single-byte call employing modified page zero

addressing.

11.10 BIT

The NSC800 allows setting, resetting, and testing of individ-

ual bits in registers and memory data bytes.

Example:

Operation: Set bit 2 in the L register

Mnemonic: SET 2,L

Opcode:

TL/C/5171–56

Bit addressing allows the selection of bit 2 in the L register

selected by register addressing.

12.0 Instruction Set

This section details the entire NSC800 instruction set in

terms of

#Opcode

#Instruction

#Function

#Timing

#Addressing Mode

The instructions are grouped in order under the following

functional headings:

#8-Bit Loads

#16-Bit Loads

#8-Bit Arithmetic

#16-Bit Arithmetic

#Bit Set, Reset, and Test

#Rotate and Shift

#Exchanges

#Memory Block Moves and Searches

#Input/Output

#CPU Control

#Program Control

12.1 Instruction Set Index

Alphabetical

Assembly Operation Page

Mnemonic

ADC A,m1Add, with carry, memory location contents to Accumulator 40

ADC A,n Add, with carry, immediate data n to Accumulator 38

ADC A,r Add, with carry, register r contents to Accumulator 36

ADC HL,pp Add, with carry, register pair pp to HL 43

ADD A,m1Add memory location contents to Accumulator 40

ADD A,n Add immediate data n to Accumulator 38

ADD A,r Add register r contents to Accumulator 36

ADD HL,pp Add register pair pp to HL 43

ADD IX,pp Add register pair pp to IX 43

ADD IY,pp Add register pair pp to IY 43

ADD ss,pp Add register pair pp to contents of register pair ss 43

AND m1Logical ‘AND’ memory contents to Accumulator 41

AND n Logical ‘AND’ immediate data to Accumulator 39

AND r Logical ‘AND’ register r contents to Accumulator 36

BIT b,m1Test bit b of location m145

BIT b,r Test bit b of register r 44

CALL cc,nn Call subroutine at location nn if condition cc is true 56

CALL nn Unconditional call to subroutine at location nn 56

CCF Complement carry flag 38

CP m1Compare memory contents with Accumulator 42

CP n Compare immediate data n with Accumulator 40

CP r Compare register r to contents with Accumulator 37

CPD Compare location (HL) and Accumulator, decrement HL and BC 50

CPDR Compare location (HL) and Accumulator, decrement HL and BC; 51

repeat until BC e0

CPI Compare location (HL) and Accumulator, increment HL, decrement BC 50

CPIR Compare location (HL) and Accumulator, increment HL, decrement BC; 51

repeat until BC e0

CPL Complement Accumulator (1’s complement) 37

DAA Decimal adjust Accumulator 38

DEC m1Decrement data in memory location m142

DEC r Decrement register r contents 37

DEC rr Decrement register pair rr contents 44

12.1 Instruction Set Index (Continued)

Alphabetical

Assembly Operation Page

Mnemonic

DI Disable interrupts 54

DJNZ,d Decrement B and jump relative B i056

EI Enable interrupts 54

EX (SP),ss Exchange the location (SP) with register ss 50

EX AF,A’F’ Exchange the contents of AF and A’F’ 49

EX DE,HL Exchange the contents of DE and HL 49

EXX Exchange the contents of BC, DE and HL with the contents 50

of B’C, D’E’ and H’L’, respectively

HALT Halt (wait for interrupt or reset) 54

IM 0 Set interrupt mode 0 54

IM 1 Set interrupt mode 1 55

IM 2 Set interrupt mode 2 55

IN A,(n) Load Accumulator with input from device (n) 52

IN r,(C) Load register r with input from device (C) 52

INC m1Increment data in memory location m142

INC r Increment register r 37

INC rr Increment contents of register pair rr 43

IND Load location (HL) with input from port (C), decrement HL and B 52

INDR Load location (HL) with input from port (C), decrement HL and B; repeat until B e054

INI Load location (HL) with input from port (C), increment HL, decrement B 52

INIR Load location (HL) with input from port (C), increment HL, decrement B; 53

repeat until B e0

JP cc,nn Jump to location nn, if condition cc is true 55

JP nn Unconditional jump to location nn 55

JP (ss) Unconditional jump to location (ss) 55

JR d Unconditional jump relative to PC ad55

JR kk,d Jump relative to PC ad, if kk true 55

LD A,I Load Accumulator with register I contents 32

LD A,m2Load Accumulator from location m233

LD A,R Load Accumulator with register R contents 32

LD I,A Load register I with Accumulator contents 32

LD m1,n Load memory with immediate data n 33

LD m1,r Load memory from register r 32

LD m2,A Load memory from Accumulator 33

LD (nn),rr Load memory location nn with register pair rr 34

LD r,m1Load register r from memory 33

LD r,n Load register with immediate data n 32

LD R,A Load register R from Accumulator 32

LD rd,rsLoad destination register rdfrom source register rs32

LD rr,(nn) Load register pair rr from memory location nn 35

LD rr,nn Load register pair rr with immediate data nn 34

LD SP,ss Load SP from register pair ss 34

LDD Load location (DE) with location (HL), decrement DE, HL and BC 50

LDDR Load location (DE) with location (HL), decrement DE, HL and BC; repeat until BC e051

LDI Load location (DE) with location (HL), increment DE and HL, decrement BC 50

LDIR Load location (DE) with location (HL), increment DE and HL, decrement BC; 51

repeat until BC e0

NEG Negate Accumulator (2’s complement) 38

NOP No operation 54

12.1 Instruction Set Index (Continued)

Alphabetical

Assembly Operation Page

Mnemonic

OR m1Logical ‘OR’ of memory location contents and accumulator 41

OR n Logical ‘OR’ of immediate data n and Accumulator 39

OR r Logical ‘OR’ of register r and Accumulator 37

OTDR Load output port (C) with location (HL), decrement HL and B; repeat until B e054

OTIR Load output port (C) with location (HL), increment HL, decrement B; 53

repeat until B e0

OUT (C),r Load output port (C) with register r 52

OUT (n),A Load output port (n) with Accumulator 53

OUTD Load output port (C) with location (HL), decrement HL and B 53

OUTI Load output port (C) with location (HL), increment HL, decrement B 52

POP qq Load register pair qq with top of stack 35

PUSH qq Load top of stack with register pair qq 35

RES b,m1Reset bit b of memory location m144

RES b,r Reset bit b of register r 44

RET Unconditional return from subroutine 56

RET cc Return from subroutine, if cc true 56

RETI Unconditional return from interrupt 56

RETN Unconditional return from non-maskable interrupt 57

RL m1Rotate memory contents left through carry 47

RL r Rotate register r left through carry 45

RLA Rotate Accumulator left through carry 45

RLC m1Rotate memory contents left circular 47

RLC r Rotate register r left circular 45

RLCA Rotate Accumulator left circular 45

RLD Rotate digit left and right between Accumulator and memory (HL) 49

RR m1Rotate memory contents right through carry 48

RR r Rotate register r right through carry 46

RRA Rotate Accumulator right through carry 48

RRC m1Rotate memory contents right circular 47

RRC r Rotate register r right circular 45

RRCA Rotate Accumulator right circular 46

RRD Rotate digit right and left between Accumulator and memory (HL) 49

RST P Restart to location P 57

SBC A,m1Subtract, with carry, memory contents from Accumulator 41

SBC A,n Subtract, with carry, immediate data n from Accumulator 39

SBC A,r Subtract, with carry, register r from Accumulator 36

SBC HL,pp Subtract, with carry, register pair pp from HL 43

SCF Set carry flag 38

SET b,m1Set bit b in memory location m1contents 44

SET b,r Set bit b in register r 44

SLA m1Shift memory contents left, arithmetic 48

SLA r Shift register r left, arithmetic 46

SRA m1Shift memory contents right, arithmetic 48

SRA r Shift register r right, arithmetic 46

SRL m1Shift memory contents right, logical 48

SRL r Shift register r right, logical 46

SUB m1Subtract memory contents from Accumulator 40

SUB n Subtract immediate data n from Accumulator 39

SUB r Subtract register r from Accumulator 36

XOR m1Exclusive ‘OR’ memory contents and Accumulator 42

XOR n Exclusive ‘OR’ immediate data n and Accumulator 39

XOR r Exclusive ‘OR’ register r and Accumulator 37

12.0 Instruction Set (Continued)

12.2 INSTRUCTION SET MNEMONIC NOTATION

In the following instruction set listing, the notations used are

shown below.

b: Designates one bit in a register or memory location.

Bit address mode uses this indicator.

cc: Designates condition codes used in conditional

Jumps, Calls, and Return instruction; may be:

NZ eNon-Zero (Z flage0)

ZeZero (Z flage1)

NC eNon-Carry (C flage0)

CeCarry (C flage1)

PO eParity Odd or No Overflow (P/Ve0)

PE eParity Even or Overflow (P/Ve1)

PePositive (Se0)

MeNegative (Se1)

d: Designates an 8-bit signed complement displace-

ment. Relative or indexed address modes use this

indicator.

kk: Subset of cc condition codes used in conjunction with

conditional relative jumps; may be NZ, Z, NC or C.

m1: Designates (HL), (IXad) or (IYad). Register indirect

or indexed address modes use this indicator.

m2: Designates (BC), (DE) or (nn). Register indirect or di-

rect address modes use this indicator.

n: Any 8-bit binary number.

nn: Any 16-bit binary number.

p: Designates restart vectors and may be the hex values

0, 8, 10, 18, 20, 28, 30 or 38. Restart instructions

employing the modified page zero addressing mode

use this indicator.

pp: Designates the BC, DE, SP or any 16-bit register used

as a destination operand in 16-bit arithmetic opera-

tions employing the register address mode.

qq: Designates BC, DE, HL, A, F, IX, or IY during opera-

tions employing register address mode.

r: Designates A, B, C, D, E, H or L. Register addressing

modes use this indicator.

rr: Designates BC, DE, HL, SP, IX or IY. Register ad-

dressing modes use this indicator.

ss: Designates HL, IX or IY. Register addressing modes

use this indicator.

XL: Subscript L indicates the lower-order byte of a 16-bit

XH: Subscript H indicates the high-order byte of a 16-bit

( ): parentheses indicate the contents are considered a

pointer address to a memory or I/O location.

12.3 ASSEMBLED OBJECT CODE NOTATION

r Register rp Register rs Register

000 B 00BC00BC

001 C 01DE01DE

010 D 10HL10HL

011 E 11SP11AF

100 H pp Register qq Register

101 L 00BC00BC

111 A 01DE01DE

10 IX 10 HL

11 SP 11 AF

Conditions Codes:

cc Mnemonic True Flag Condition

000 NZ Ze0

001 Z Ze1

010 NC Ce0

011 C Ce1

100 PO P/Ve0

101 PE P/Ve1

110 P Se0

111 M Se1

kk Mnemonic True Flag Condition

00 NZ Ze0

01 Z Ze1

10 NC Ce0

11 C Ce1

Restart Addresses:

000 X’00

001 X’08

010 X’10

011 X’18

100 X’20

101 X’28

110 X’30

111 X’38

12.4 8-Bit Loads

LD rd,r

Load register rdwith rs:

rsNo flags affected

76543210

01 r

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Register

LD A, I

Load Accumulator with the contents of the I register.

I S: Set if negative result

Z: Set if zero result

H: Reset

P/V: Set according to IFF2(zero if

interrupt occurs during opera-

tion)

N: Reset

C: Not affected

76543210

11101101

01010111

Timing: M cycles Ð 2

T states Ð 9 (4, 5)

Addressing Mode: Register

LD I, A

Load Interrupt vector register (I) with the contents of A.

A No flags affected

76543210

11101101

01000111

Timing: M cycles Ð 2

T states Ð 9 (4, 5)

Addressing Mode: Register

LD A, R

Load Accumulator with contents of R register.

R S: Set if negative result

Z: Set if zero result

H: Reset

P/V: Set according to IFF2(zero if

interrupt occurs during opera-

tion)

N: Reset

C: Not affected

76543210

11101101

01011111

Timing: M cycles Ð 2

T states Ð 9 (4, 5)

Addressing Mode: Register

LD R, A

Load Refresh register (R) with contents of the Accumulator.

A No flags affected

76543210

11101101

01001111

Timing: M cycles Ð 2

T states Ð 9 (4, 5)

Addressing Mode: Register

LD r, n

Load register r with immediate data n.

n No flags affected

76543210

00 r 110

Timing: M cycles Ð 2

T states Ð 7 (4, 3)

Addressing Mode: Source Ð Immediate

Destination Ð Register

LD m1,r

Load memory from reigster r.

r No flags affected

76543210

01110 r LD(HL), r

Timing: M cycles Ð 2

T states Ð 7 (4,3)

Addressing Mode: Source Ð Register

Destination Ð Register Indirect

76 5 43210LD (IXad), r(for NXe0)

11N

X11101LD (IYad), r(for NXe1)

01110 r

Timing: M cycles Ð 2

T states Ð 19 (4, 4, 3, 5, 3)

Addressing Mode: Source Ð Register

Destination Ð Indexed

12.4 8-Bit Loads (Continued)

LD m2,A

Load memory from the Accumulator.

A No flags affected

76543210

00000010LD(BC), A

00010010LD(DE), A

Timing: M cycles Ð 2

T states Ð 7 (4, 3)

Addressing Mode: Source Ð Register (Implied)

Destination Ð Register Indirect

76543210

00110010LD(nn), A

n (low-order byte)

n (high-order byte)

Timing: M cycles Ð 4

T states Ð 3 (4, 3, 3, 3)

Addressing Mode: Source Ð Register (Implied)

Destination Ð Direct

LD m1,n

Load memory with immediate data.

n No flags affected

76543210

00110110 LD(HL), n

Timing: M cyclesÐ3

T statesÐ10 (4, 3, 3)

Addressing Mode: SourceÐImmediate

DestinationÐRegister Indirect

76 5 43210 LD (IX ad), n(for NXe0)

11N

X11101 LD (IY ad), n(for NXe1)

00 1 10110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐImmediate

DestinationÐIndexed

MEMORY TO REGISTER

LD r, m1

Load register r from memory location m1.

m1No flags affected

76543210

0 1 r 1 1 0 LD R, (HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐRegister

76 5 43210LD r, (IX ad) (for NXe0)

11N

X11101LD r, (IY ad) (for NXe1)

01 r 110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐRegister

LD A, m2

Load the Accumulator from memory location m2.

m2No flags affected

76543210 LD A, (BC)

00001010

00011010 LDA,(DE)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐRegister (Implied)

76543210

00111010 LDA,(nn)

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ4

T statesÐ13 (4, 3, 3, 3)

Addressing Mode: SourceÐImmediate Extended

DestinationÐRegister (Implied)

12.5 16-Bit Loads

LD rr, nn

Load 16-bit register pair with immediate data.

rr,

nn No flags affected

76543210 LD BC, nn

LD DE, nn

00 rp 0001

LD HL, nn

LD SP, nn

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ3

T statesÐ10 (4, 3, 3)

Addressing Mode: SourceÐImmediate Extended

DestinationÐRegister

76 5 43210 LD IX, nn (for NXe0)

11N

X11101 LD IY, nn (for NXe1)

00 1 00001

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ4

T statesÐ14 (4, 4, 3, 3)

Addressing Mode: SourceÐImmediate Extended

DestinationÐRegister

LD SP, ss

Load the SP from 16-bit register ss.

ss No flags affected

76543210

11111001 LDSP,HL

Timing: M cyclesÐ1

T statesÐ6

Addressing Mode: SourceÐRegister

DestinationÐRegister (Implied)

76 5 43210 LD SP, IX (for NXe0)

11N

X11101 LD SP, IY (for NXe1)

11 1 11001

Timing: M cyclesÐ2

T statesÐ10 (4, 6)

Addressing Mode: SourceÐRegister

DestinationÐRegister (Implied)

LD (nn), rr

Load memory location nn with contents of 16-bit register, rr.

(nn)

rrLNo flags affected

(nn a1)

rrH

76543210 LD (nn), HL

(note an alternate

00100010

opcode below)

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ5

T statesÐ16 (4, 3, 3, 3, 3)

Addressing Mode: SourceÐRegister

DestinationÐDirect

76543210 LD (nn), BC

LD (nn), DE

11101101

LD (nn), HL

LD (nn), SP

01 rp 0011

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ6

T statesÐ20 (4, 4, 3, 3, 3, 3)

Addressing Mode: SourceÐRegister

DestinationÐDirect

76 5 43210 LD (nn), IX (for NXe0)

11N

X11101 LD (nn) IY (for NXe1)

00 1 00010

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ6

T statesÐ20 (4, 4, 3, 3, 3, 3)

Addressing Mode: SourceÐRegister

DestinationÐDirect

12.5 16-Bit Loads (Continued)

PUSH qq

Push the contents of register pair qq onto the memory

stack.

(SP–1)

qqHNo flags affected

(SP–2)

qqL

SP b2

76543210PUSH BC

11 rs 0101PUSH DE

PUSH HL

PUSH AF

Timing: M cyclesÐ3

T statesÐ11 (5, 3, 3)

Addressing Mode: SourceÐRegister

DestinationÐRegister Indirect

(Stack)

76 5 43210 PUSH IX (for NXe0)

11N

X11101 PUSH IY (for NXe1)

11 1 00101

Timing: M cyclesÐ3

T statesÐ15 (4, 5, 3, 3)

Addressing Mode: SourceÐRegister

DestinationÐRegister Indirect

(Stack)

MEMORY TO REGISTER

LD rr, (nn)

Load 16-bit register from memory location nn.

rrL

(nn) No flags affected

rrH

(nn a1)

76543210 LD HL, (nn)

00101010 (note an alternate

opcode below)

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ5

T statesÐ16 (4, 3, 3, 3, 3)

Addressing Mode: SourceÐDirect

DestinationÐRegister

76543210 LD BC, (nn)

LD DE, (nn)

11101101

LD HL, (nn)

LD SP, (nn)

01 rp 0011

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ6

T statesÐ20 (4, 4, 3, 3, 3, 3)

Addressing Mode: SourceÐDirect

DestinationÐRegister

76 5 43210 LD IX, (nn)(for NXe0)

11N

X11101 LD IY, (nn) (for NXe1)

00 1 01010

n (low-order byte)

n (high-order byte)

Timing: M cyclesÐ6

T statesÐ20 (4, 4, 3, 3, 3, 3)

Addressing Mode: SourceÐDirect

DestinationÐRegister

POP qq

Pop the contents of the memory stack to register qq.

qqL

(SP) No flags affected

qqH

(SP a1)

SP a2

76543210POP BC

11 rs 0001POP DE

POP HL

POP AF

Timing: M cyclesÐ3

T statesÐ10 (4, 3, 3)

Addressing Mode: SourceÐRegister Indirect

(Stack)

DestinationÐRegister

76 5 43210 POP IX (for NXe0)

11N

X11101 POP IY (for NXe1)

11 1 00001

Timing: M cyclesÐ4

T statesÐ14 (4, 4, 3, 3)

Addressing Mode: SourceÐRegister Indirect

(Stack)

DestinationÐRegister

12.6 8-Bit Arithmetic

Hex Hex

CValue HValue Number C

Op Before In Before In Added After

DAA Upper DAA Lower To DAA

Digit Digit Byte

(Bits 7-4) (Bits 3-0)

0 0-9 0 0-9 00 0

0 0-8 0 A-F 06 0

0 0-9 1 0-3 06 0

ADD 0 A-F 0 0-9 60 1

ADC 0 9-F 0 A-F 66 1

INC 0 A-F 1 0-3 66 1

1 0-2 0 0-9 60 1

1 0-2 0 A-F 66 1

1 0-3 1 0-3 66 1

SUB 0 0-9 0 0-9 00 0

SBC 0 0-8 1 6-F FA 0

DEC 1 7-F 0 0-9 A0 1

NEG 1 6-F 1 6-F 9A 1

ADD A, r

Add contents of register r to the

Accumulator.

Aar S: Set if negative result

Z: Set if zero result

H: Set if carry from bit 3

P/V: Set according to overflow

condition

N: Reset

C: Set if carry from bit 7

76543210

10000 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

ADC A, r

Add contents of register r, plus the carry flag, to the Accu-

mulator.

AaraCY S: Set if negative result

Z: Set if zero result

H: Set if carry from bit 3

P/V: Set if result exceeds 2’s com-

plement range

N: Reset

C: Set if carry from bit 7

76543210

10001 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

SUB r

Subtract the contents of register r from the Accumulator.

Abr S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow

76543210

10010 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

SBC A, r

Subtract contents of register r and the carry bit C from the

Accumulator.

AbrbCY S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow

76543210

10011 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

AND r

Logically AND the contents of the r register and the Accu-

mulator.

A!r S: Set if result is negative

Z: Set if result is zero

H: Set

P/V: Set if result parity is even

N: Reset

C: Reset

12.6 8-Bit Arithmetic (Continued)

76543210

10100 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

OR r

Logically OR the contents of the r register and the Accumu-

lator.

A¶r S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Reset

76543210

10110 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

XOR r

Logically exclusively OR the contents of the r register with

the Accumulator.

AZr S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Reset

76543210

10101 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

INC r

Increment register r.

ra1 S: Set if result is negative

Z: Set if result is zero

H: Set if carry from bit 3

P/V: Set only if r was X’7F before

operation

N: Reset

C: N/A

76543210

00 r 100

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐRegister

CP r

Compare the contents of register r with the Accumulator

and set the flags accordingly.

Abr S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow

76543210

10111 r

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐImplied

DEC r

Decrement the contents of register r.

rb1 S: Set if result is negative

Z: Set if result is zero

H: Set according to a borrow from

bit 4

P/V: Set only if r was X’80 prior to

operation

N: Set

C: N/A

76543210

00 r 101

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: SourceÐRegister

DestinationÐRegister

CPL

Complement the Accumulator (1’s complement).

A S: N/A

Z: N/A

H: Set

P/V: N/A

N: Set

C: N/A

12.6 8-Bit Arithmetic (Continued)

76543210

00101111

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: Implied

NEG

Negate the Accumulator (2’s complement).

0bA S: Set if result is negative

Z: Set if result is zero

H: Set according to borrow from

bit 4

P/V: Set only if Accumulator was

X’80 prior to operation

N: Set

C: Set only if Accumulator was not

X’00 prior to operation

76543210

11101101

01000100

Timing: M cyclesÐ2

T statesÐ8 (4, 4)

Addressing Mode: Implied

CCF

Complement the carry flag.

CY S: N/A

Z: N/A

H: Previous carry

P/V: N/A

N: Reset

C: Complement of previous carry

76543210

00111111

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: Implied

SCF

Set the carry flag.

1 S: N/A

Z: N/A

H: Reset

P/V: N/A

N: Reset

C: Set

76543210

00110111

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: Implied

DAA

Adjust the Accumulator for BCD addition and subtraction

operations. To be executed after BCD data has been oper-

ated upon the standard binary ADD, ADC, INC, SUB, SBC,

DEC or NEG instructions (see ‘‘Register Addressing Arith-

metic’’ table).

ÐÐÐ S: Set according to bit 7 of result

Z: Set if result is zero

H: Set according to instructions

P/V: Set according to parity of result

N: N/A

C: Set according to instructions

76543210

00100111

Timing: M cyclesÐ1

T statesÐ4

Addressing Mode: Implied

IMMEDIATELY ADDRESSED ARITHMETIC

ADD A, n

Add the immediate data n to the Accumulator.

Aan S: Set if result is negative

Z: Set if result is zero

H: Set if carry from bit 3

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Reset

C: Set if carry from bit 7

76543210

11000110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐImmediate

DestinationÐImplied

ADC A, n

Add, with carry, the immediate data n and the Accumulator.

AanaCY S: Set if result is negative

Z: Set if result is zero

H: Set if carry from bit 3

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Reset

C: Set according to carry from bit

12.6 8-Bit Arithmetic (Continued)

76543210

11001110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐImmediate

DestinationÐImplied

SUB n

Subtract the immediate data n from the Accumulator.

Abn S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow

condition

76543210

11010110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐImmediate

DestinationÐImplied

SBC A, n

Subtract, with carry, the immediate data n from the Accumu-

lator.

AbnbCY S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow

condition

76543210

11011110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐImmediate

DestinationÐImplied

AND n

The immediate data n is logically AND’ed to the Accumula-

tor.

A!n S: Set if result is negative

Z: Set if result is zero

H: Set

P/V: Set if result parity is even

N: Reset

C: Reset

76543210

11100110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐImmediate

DestinationÐImplied

OR n

The immediate data n is logically OR’ed to the contents of

the Accumulator.

A¶s S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Reset

76543210

11110110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐImmediate

DestinationÐImplied

XOR n

The immediate data n is exclusively OR’ed with the Accu-

mulator.

AZn S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Reset

12.6 8-Bit Arithmetic (Continued)

76543210

11101110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐImmediate

DestinationÐImplied

CP n

Compare the immediate data n with the contents of the Ac-

cumulator via subtraction and return the appropriate flags.

The contents of the Accumulator are not affected.

Abn S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow condi-

tion

76543210

11111110

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: Immediate

MEMORY ADDRESSED ARITHMETIC

ADD A, m1

Add the contents of the memory location m1to the Accumu-

lator.

Aam1S: Set if result is negative

Z: Set if result is zero

H: Set if carry from bit 3

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Reset

C: Set according to carry from bit

76543210

10000110 ADDA,(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐImplied

76 5 43210ADD A, (IX ad) (for NXe0)

11N

X11101ADD A, (IY ad) (for NXe1)

10 0 00110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

ADC A, m1

Add the contents of the memory location m1plus the carry

to the Accumulator.

Aam1aCY S: Set if result is negative

Z: Set if result is zero

H: Set if carry from bit 3

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Reset

C: Set according to carry from bit

76543210

10001110 ADCA,(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐImplied

76 5 43210 ADC A, (IX ad) (for NXe0)

11N

X11101 ADC A, (IY ad) (for NXe1)

10 0 01110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

SUB m1

Subtract the contents of memory location m1from the Ac-

cumulator.

Abm1S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow condi-

tion

12.6 8-Bit Arithmetic (Continued)

76543210

10010110 SUB(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐImplied

76 5 43210 SUB (IX ad) (for NXe0)

11N

X11101 SUB (IY ad) (for NXe1)

10 0 10110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

SBC A, m1

Subtract, with carry, the contents of memory location m1

from the Accumulator.

Abm1bCY S: Set if result is negative

Z: Set if result is zero

H: Set if carry from bit 3

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow

condition

76543210

10011110 SBCA,(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐImplied

76 5 43210 SBC A, (IX ad) (for NXe0)

11N

X11101 SBC A, (IY ad) (for NXe1)

10 0 11110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

AND m1

The data in memory location m1is logically AND’ed to the

Accumulator.

A!m1S: Set if result is negative

Z: Set if result is zero

H: Set

P/V: Set if result parity is even

N: Reset

C: Reset

76543210

10100110 AND(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐImplied

76 5 43210 AND (IX ad) (for NXe0)

11N

X11101 AND (IY ad) (for NXe1)

10 1 00110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

OR m1

The data in memory location m1is logically OR’ed with the

Accumulator.

A¶m1S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Reset

76543210

10110110 OR(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indexed

DestinationÐImplied

76 5 43210 OR (IX ad) (for NXe0)

11N

X11101 OR (IY ad) (for NXe1)

10 1 10110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

12.6 8-Bit Arithmetic (Continued)

XOR m1

The data in memory location m1is exclusively OR’ed with

the data in the Accumulator.

AZm1S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Reset

76543210

10101110 XOR(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indexed

DestinationÐImplied

76 5 43210 XOR (IX ad) (for NXe0)

11N

X11101 XOR (IY ad) (for NXe1)

10 1 01110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

CP m1

Compare the data in memory location m1with the data in

the Accumulator via subtraction.

Abm1S: Set if result is negative

Z: Set if result is zero

H: Set if borrow from bit 4

P/V: Set if result exceeds 8-bit 2’s

complement range

N: Set

C: Set according to borrow

condition

76543210

10111110 CP(HL)

Timing: M cyclesÐ2

T statesÐ7 (4, 3)

Addressing Mode: SourceÐRegister Indirect

DestinationÐImplied

76 5 43210 CP (IX ad) (for NXe0)

11N

X11101 CP (IY ad) (for NXe1)

10 1 11110

Timing: M cyclesÐ5

T statesÐ19 (4, 4, 3, 5, 3)

Addressing Mode: SourceÐIndexed

DestinationÐImplied

INC m1

Increment data in memory location m1.

m1a1 S: Set if result is negative

Z: Set if result is zero

H: Set according to carry from bit

P/V: Set if data was X’7F before op-

eration

N: Reset

C: N/A

76543210

00110100 INC(HL)

Timing: M cyclesÐ3

T statesÐ11 (4, 4, 3)

Addressing Mode: SourceÐRegister Indexed

DestinationÐRegister Indexed

76 5 43210 INC (IX ad) (for NXe0)

11N

X11101 INC (IY ad) (for NXe1)

00 1 10100

Timing: M cyclesÐ6

T statesÐ23 (4, 4, 3, 5, 4, 3)

Addressing Mode: SourceÐIndexed

DestinationÐIndexed

DEC m1

Decrement data in memory location m1.

m1b1 S: Set if result is negative

Z: Set if result is zero

H: Set according to borrow from

bit 4

P/V: Set only if m1was X’80 before

operation

N: Set

C: N/A

12.6 8-Bit Arithmetic (Continued)

76543210

0 0 1 1 0 1 0 1 DEC (HL)

Timing: M cycles Ð 3

T states Ð 11 (4, 4, 3)

Addressing Mode: Source Ð Register Indexed

Destination Ð Register In-

dexed

76 5 43210 DEC (IX ad) (for NXe0)

11N

X11101 DEC (IY ad) (for NXe1)

00 1 10101

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Source Ð Indexed

Destination Ð Indexed

12.7 16-Bit Arithmetic

ADD ss, pp

Add the contents of the 16-bit register rp or pp to the con-

tents of the 16-bit register ss.

ss arp S: N/A

or Z: N/A

ss app H: Set if carry from bit 11

P/V: N/A

N: Reset

C: Set if carry from bit 15

76543210

0 0 rp 1 0 0 1 ADD HL, rp

Timing: M cycles Ð 3

T states Ð 11 (4, 4, 3)

Addressing Mode: Source Ð Register

Destination Ð Register

76 5 43210 ADD IX, pp (for NXe0)

11N

X11101 ADD IY, pp (for NXe1)

00 pp 1001

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Source Ð Register

Destination Ð Register

ADC HL, pp

The contents of the 16-bit register pp are added, with the

carry bit, to the HL register.

HL app aCY

S: Set if result is negative

Z: Set if result is zero

H: Set according to carry out of bit

P/V: Set if result exceeds 16-bit 2’s

complement range

N: Reset

C: Set if carry out of bit 15

76543210

11101101

01 pp 1010

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Source Ð Register

Destination Ð Register

SBC HL, pp

Subtract, with carry, the contents of the 16-bit pp register

from the 16-bit HL register.

HL bpp bCY

S: Set if result is negative

Z: Set if result is zero

H: Set according to borrow from

bit 12

P/V: Set if result exceeds 16-bit 2’s

complement range

N: Set

C: Set according to borrow condi-

tion

76543210

11101101

01 pp 0010

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Source Ð Register

Destination Ð Register

INC rr

Increment the contents of the 16-bit register rr.

rr a1 No flags affected

76543210INC BC

00 rp 0011INC DE

INC HL

INC SP

Timing: M cycles Ð 1

T states Ð 6

Addressing Mode: Register

76 5 43210 INC IX (for NXe0)

11N

X11101 INC IY (for NXe1)

00 1 00011

Timing: M cycles Ð 2

T states Ð 10 (4, 6)

Addressing Mode: Register

12.7 16-Bit Arithmetic (Continued)

DEC rr

Decrement the contents of the 16-bit register rr.

rr b1 No flags affected

76543210DEC BC

00 rp 1011DEC DE

DEC HL

DEC SP

Timing: M cycles Ð 1

T states Ð 6

Addressing Mode: Register

76 5 43210 DEC IX (for NXe0)

11N

X11101 DEC IY (for NXe1)

00 1 01011

Timing: M cycles Ð 2

T states Ð 10 (4, 6)

Addressing Mode: Register

12.8 Bit Set, Reset, and Test

SET b, r

Bit b in register r is set.

1 No flags affected

76543210

11001011

11 b r

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Bit/Register

RES b, r

Bit b in register r is reset.

0 No flags affected

76543210

11001011

10 b r

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Bit/Register

BIT b, r

Bit b in register r is tested with the result put in the Z flag.

rbS: Undefined

Z: Inverse of tested bit

H: Set

P/V: Undefined

N: Reset

C: N/A

76543210

11001011

01 b r

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Bit/Register

MEMORY

SET b, m1

Bit b in memory location m1is set.

m1b

1 No flags affected

76543210

1 1 0 0 1 0 1 1 SET b, (HL)

11 b 110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Bit/Register Indirect

76 5 43210 SET b, (IXad) (for NXe0)

11N

X11101 SET b, (IYad) (for NXe1)

11 0 01011

11 b 110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Bit/Indexed

RES b, m1

Bit b in memory location m1is reset.

m1b

0 No flags affected

76543210

1 1 0 0 1 0 1 1 RES b, (HL)

10b110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Bit/Register Indirect

76 5 43210 RES b, (IXad) (for NXe0)

11N

X11101 RES b, (IYad) (for NXe1)

11 0 01011

10 b 110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Bit/Indexed

12.8 Bit Set, Reset, and Test (Continued)

BIT B, m1

Bit b in memory location m1is tested via the Z flag.

m1b S: Undefined

Z: Inverse of tested bit

H: Set

P/V: Undefined

N: Reset

C: N/A

76543210

1 1 0 0 1 0 1 1 BIT b, (HL)

01 b 110

Timing: M cycles Ð 3

T states Ð 12 (4, 4, 4)

Addressing Mode: Bit/Register Indirect

76 5 43210 BIT b, (IXad) (for NXe0)

11N

X11101 BIT b, (IYad) (for NXe1)

11 0 01011

01 b 110

Timing: M cycles Ð 5

T states Ð 20 (4, 4, 3, 5, 4)

Addressing Mode: Bit/Indexed

12.9 Rotate and Shift

RLC r

Rotate register r left circular.

TL/C/5171–57

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 7 of r

76543210

11001011RLCr

0 0 0 0 0 r (Note alternate for

A register below)

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register

76543210

0 0 0 0 0 1 1 1 RLCA

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Implied

(Note RLCA does not affect S, Z, or P/V flags.)

RL r

Rotate register r left through carry.

TL/C/5171–58

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 7 of r

76543210

11001011RLr

00010 r (Note alternate for

A register below)

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register

76543210

00010111 RLA

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Implied

(Note RLA does not affect S, Z, or P/V flags.)

RRC r

Rotate register r right circular.

TL/C/5171–59

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of r

12.9 Rotate and Shift (Continued)

76543210

11001011 RRCr

0 0 0 0 1 r (Note alternate for

A register below)

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register

76543210

0 0 0 0 1 1 1 1 RRCA

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Implied

(Note RRCA does not affect S, Z, or P/V flags.)

RR r

Rotate register r right through carry.

TL/C/5171–60

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of r

76543210

11001001RRr

00011 r (Note alternate for

A register below)

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register

76543210

00011111 RRA

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Implied

(Note RRA does not affect S, Z, or P/V flags.)

SLA r

Shift register r left arithmetric.

TL/C/5171–61

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 7 of r

76543210

11001011

00100 r

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register

SRA r

Shift register r right arithmetic.

TL/C/5171–62

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of r

76543210

11001011

00101 r

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register

SRL r

Shift register r right logical.

TL/C/5171–63

S: Reset

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of r

76543210

11001011

00111 r

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register

12.9 Rotate and Shift (Continued)

MEMORY

RLC m1

Rotate date in memory location m1left circular.

TL/C/5171–64

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 7 of m1

76543210

1 1 0 0 1 0 1 1 RLC (HL)

00000110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Register indirect

76 5 43210 RLC (IXad) (for NXe0)

11N

X11101 RLC (IYad) (for NXe1)

11 0 01011

00 0 00110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Indexed

RL m1

Rotate the data in memory location m1left though carry.

TL/C/5171–65

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 7 of m1

76543210

1 1 0 0 1 0 1 1 RL (HL)

00010110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Register Indirect

76 5 43210 RL (IXad) (for NXe0)

11N

X11101 RL (IYad) (for NXe1)

11 0 01011

00 0 10110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Indexed

RRC m1

Rotate the data in memory location m1right circular.

TL/C/5171–66

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of m1

76543210

1 1 0 0 1 0 1 1 RRC (HL)

00001110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Register Indirect

76 5 43210 RRC (IX ad) (for NXe0)

11N

X11101 RRC (IY ad) (for NXe1)

11 0 01011

00 0 01110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Indexed

12.9 Rotate and Shift (Continued)

RR m1

Rotate the data in memory location m1right through the

carry.

TL/C/5171–67

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of m1

76543210

1 1 0 0 1 0 1 1 RR (HL)

00011110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Register Indirect

76 5 43210 RR (IX ad) (for NXe0)

11N

X11101 RR (IY ad) (for NXe1)

11 0 01011

00 0 11110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Indexed

SLA m1

Shift the data in memory location m1left arithmetic.

TL/C/5171–68

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 7 of m1

76543210

1 1 0 0 1 0 1 1 SLA (HL)

00100110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Register Indirect

76 5 43210 SLA (IX ad) (for NXe0)

11N

X11101 SLA (IY ad) (for NXe1)

11 0 01011

00 1 00110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Indexed

SRA m1

Shift the data in memory location m1right arithmetic.

TL/C/5171–69

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of m1

76543210

1 1 0 0 1 0 1 1 SRA (HL)

00101110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Register Indirect

76 5 43210 SRA (IX ad) (for NXe0)

11N

X11101 SRA (IY ad) (for NXe1)

11 0 01011

00 1 01110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Indexed

SRL m1

Shift right logical the data in memory location m1.

TL/C/5171–70

S: Reset

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: Set according to bit 0 of m1

12.9 Rotate and Shift (Continued)

76543210

1 1 0 0 1 0 1 1 SRL (HL)

00111110

Timing: M cycles Ð 4

T states Ð 15 (4, 4, 4, 3)

Addressing Mode: Register Indirect

76 5 43210 SRL (IX ad) (for NXe0)

11N

X11101 SRL (IY ad) (for NXe1)

11 0 01011

00 1 11110

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 5, 4, 3)

Addressing Mode: Indexed

RLD

Rotate digit left and right between the Accumulator and

memory (HL).

TL/C/5171–71

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: N/A

76543210

11101101

01101111

Timing: M cycles Ð 5

T states Ð 18 (4, 4, 3, 4, 3)

Addressing Mode: Implied/Register Indirect

RRD

Rotate digit right and left between the Accumulator and

memory (HL).

TL/C/5171–72

S: Set if result is negative

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: N/A

76543210

11101101

01100111

Timing: M cycles Ð 5

T states Ð 18 (4, 4, 3, 4, 3)

Addressing Mode: Implied/Register Indirect

12.10 Exchanges

EX DE, HL

Exchange the contents of the 16-bit register pairs DE and

HL.

HL No flags affected

76543210

11101011

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Register

EX AF, A’F’

The contents of the Accumulator and flag register are ex-

changed with their corresponding alternate registers, that is

A and F are exchanged with A’ and F’.

A’ No flags affected

F’

76543210

00001000

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Register

12.10 Exchanges (Continued)

EXX

Exchange the contents of the BC, DE, and HL registers with

their corresponding alternate register.

B’C’ No flags affected

D’E’

H’L’

76543210

11011001

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Implied

EX (SP), ss

Exchange the two bytes at the top of the external memory

stack with the 16-bit register ss.

(SP)

SSLNo flags affected

(SP a1)

SSH

76543210

1 1 1 0 0 0 1 1 EX (SP), HL

Timing: M cycles Ð 5

T states Ð 19 (4, 3, 4, 3, 5)

Addressing Mode: Register/Register Indirect

76 5 43210 EX (SP), IX (for NXe0)

11N

X11101 EX (SP),IY (for NXe1)

11 1 00011

Timing: M cycles Ð 6

T states Ð 23 (4, 4, 3, 4, 3, 5)

Addressing Mode: Register/Register Indirect

12.11 Memory Block Moves and

Searches

SINGLE OPERATIONS

LDI

Move data from memory location (HL) to memory location

(DE), increment memory pointers, and decrement byte

counter BC.

(DE)

(HL) S: N/A

DE a1 Z: N/A

HL a1 H: Reset

BC b1 P/V: Set if BC b1i0, other-

wise reset

N: Reset

C: N/A

76543210

11101101

10100000

Timing: M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

LDD

Move data from memory location (HL) to memory location

(DE), and decrement memory pointer and byte counter BC.

(DE)

(HL) S: N/A

DE b1 Z: N/A

HL b1 H: Reset

BC b1 P/V: Set if BC b1i0, other-

wise reset

N: Reset

C: N/A

76543210

11101101

10101000

Timing: M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

CPI

Compare data in memory location (HL) to the Accumulator,

increment the memory pointer, and decrement the byte

counter. The Z flag is set if the comparison is equal.

Ab(HL) S: Set if result of comparison sub-

tract is negative

HL a1

BC b1Z: Set if result of comparison is

1zero

if A e(HL) H: Set according to borrow from

bit 4

P/V: Set if BC b1i0, otherwise

reset

N: Set

C: N/A

76543210

11101101

10100001

Timing: M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

CPD

Compare data in memory location (HL) to the Accumulator,

and decrement the memory pointer and byte counter. The Z

flag is set if the comparison is equal.

Ab(HL) S: Set if result is negative

HL b1 Z: Set if result of comparison is

zero

BC b1

H: Set according to borrow from

1bit 4

if A e(HL) P/V: Set if BC b1i0, otherwise

reset

N: Set

C: N/A

12.11 Memory Block Moves and Searches (Continued)

76543210

11101101

10101001

Timing: M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

REPEAT OPERATIONS

LDIR

Move data from memory location (HL) to memory location

(DE), increment memory pointers, decrement byte counter

BC, and repeat until BC e0.

(DE)

(HL) S: N/A

DE a1 Z: N/A

HL a1 H: Reset

BC b1 P/V: Reset

Repeat until N: Reset

BC e0 C: N/A

76543210

11101101

10110000

Timing: For BCi0 M cycles Ð 5

T states Ð 21 (4, 4, 3, 5, 5)

For BCe0 M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

(Note that each repeat is accomplished by a decrement of

the BC, so that refresh, etc. continues for each cycle.)

LDDR

Move data from memory location (HL) to memory location

(DE), decrement memory pointers and byte counter BC, and

repeat until BC e0.

(DE)

(HL) S: N/A

DE b1 Z: N/A

HL b1 H: Reset

BC b1 P/V: Reset

Repeat until N: Reset

BC e0 C: N/A

76543210

11101101

10111000

Timing: For BCi0 M cycles Ð 5

T states Ð 21 (4, 4, 3, 5, 5)

For BCe0 M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

(Note that each repeat is accomplished by a decrement of

the BC, so that refresh, etc. continues for each cycle.)

CPIR

Compare data in memory location (HL) to the Accumulator,

increment the memory, decrement the byte counter BC, and

repeat until BC e0 or (HL) equals A.

Ab(HL) S: Set if sign of subtraction per-

formed for comparison is nega-

HL a1tive

BC b1Z: Set if A e(HL), otherwise reset

Repeat until BC e0H: Set according to borrow from

or A e(HL) bit 4

P/V: Set if BC b1i0, otherwise

reset

N: Set

C: N/A

76543210

11101101

10110001

Timing: For BC i0 M cycles Ð 5

T states Ð 21 (4, 4, 3, 5, 5)

For BC e0 M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

(Note that each repeat is accomplished by a decrement of

the PC, so that refresh, etc. continues for each cycle.)

CPDR

Compare data in memory location (HL) to the contents of

the Accumulator, decrement the memory pointer and byte

counter BC, and repeat until BC e0, or until (HL) equals

the Accumulator.

Ab(HL) S: Set if sign of subtraction per-

formed for comparison is nega-

HL b1tive

BC b1Z: Set according to equality of A

Repeat until BC e0and (HL), set if true

or A e(HL) H: Set according to borrow from

bit 4

P/V: Set if BC b1i0, otherwise

reset

N: Set

C: N/A

76543210

11101101

10111001

Timing: For BC i0 M cycles Ð 5

T states Ð 21 (4, 4, 3, 5, 5)

For BC e0 M cycles Ð 4

T states Ð 16 (4, 4, 3, 5)

Addressing Mode: Register Indirect

(Note that each repeat is accomplished by a decrement of

the BC, so that refresh, etc. continues for each cycle.)

12.12 Input/Output

IN A, (n)

Input data to the Accumulator from the I/O device at ad-

dress N.

(n) No flags affected

76543210

11011011

Timing: M cycles Ð 3

T states Ð 11 (4, 3, 4)

Addressing Mode: Source Ð Direct

Destination Ð Register

IN r, (C)

Input data to register r from the I/O device addressed by the

contents of register C. If re110 only flags are affected.

Z: Set if result is zero

H: Reset

P/V: Set if result parity is even

N: Reset

C: N/A

76543210

11101101

01 r 000

Timing: M cycles Ð 3

T states Ð 12 (4, 4, 4)

Addressing Mode: Source Ð Register Indirect

Destination Ð Register

OUT (C), r

Output register r to the I/O device addressed by the con-

tents of register C.

(C)

r No flags affected

76543210

11101101

01 r 001

Timing: M cycles Ð 3

T states Ð 12 (4, 4, 4)

Addressing Mode: Source Ð Register

Destination Ð Register Indirect

INI

Input data from the I/O device addressed by the contents of

of the HL register. The HL pointer is incremented and the

byte counter B is decremented.

(HL)

Bb1 Z: Set if Bb1e0, otherwise reset

HL a1 H: Undefined

P/V: Undefined

N: Set

C: N/A

76543210

11101101

10100010

Timing: M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

OUTI

Output data from memory location (HL) to the I/O device at

port address (C), increment the memory pointer, and decre-

ment the byte counter B.

(C)

(HL) S: Undefined

Bb1 Z: Set if Bb1e0, otherwise reset

HL a1 H: Undefined

P/V: Undefined

N: Set

C: N/A

76543210

11101101

10100011

Timing: M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

IND

Input data from I/O device at port address (C) to memory

location (HL), and decrement HL memory pointer and byte

counter B.

(HL)

HL b1 Z: Set if Bb1e0, otherwise reset

Bb1 H: Undefined

P/V: Undefined

N: Set

C: N/A

76543210

11101101

10101010

Timing: M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

12.12 Input/Output (Continued)

OUT (n), A

Output the Accumulator to the I/O device at address n.

(n)

A No flags affected

76543210

11010011

Timing: M cycles Ð 3

T states Ð 11 (4, 3, 4)

Addressing Mode: Source Ð Register

Destination Ð Direct

OUTD

Data is output from memory location (HL) to the I/O device

at port address (C), and the HL memory pointer and byte

counter B are decremented.

(C)

(HL) S: Undefined

Bb1 Z: Set if Bb1e0, otherwise reset

HL b1 H: Undefined

P/V: Undefined

N: Set

C: N/A

76543210

11101101

10101011

Timing: M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

INIR

Data is input from the I/O device at port address (C) to

memory location (HL), the HL memory pointer is increment-

ed, and the byte counter B is decremented. The cycle is

repeated until B e0.

(Note that B is tested for zero after it is decremented. By

loading B initially with zero, 256 data transfers will take

place.)

(HL)

HL a1 Z: Set

Bb1 H: Undefined

Repeat until B e0 P/V: Undefined

N: Set

C: N/A

76543210

11101101

10110010

Timing: For B i0 M cycles Ð 5

T states Ð 21 (4, 5, 3, 4, 5)

For B e0 M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

(Note that at the end of each data transfer cycle, interrupts

may be recognized and two refresh cycles will be per-

formed.)

OTIR

Data is output to the I/O device at port address (C) from

memory location (HL), the HL memory pointer is increment-

ed, and the byte counter B is decremented. The cycles are

repeated until B e0.

(Note that B is tested for zero after it is decremented. By

loading B initially with zero, 256 data transfers will take

place.)

(C)

(HL) S: Undefined

HL a1 H: Undefined

Bb1 Z: Set

Repeat until B e0 P/V: Undefined

N: Set

C: N/A

76543210

11101101

10110011

Timing: For B i0 M cycles Ð 5

T states Ð 21 (4, 5, 3, 4, 5)

For B e0 M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

(Note that at the end of each data transfer cycle, interrupts

may be recognized and two refresh cycles will be per-

formed.)

12.12 Input/Output (Continued)

INDR

Data is input from the I/O device at address (C) to memory

location (HL), then the HL memory pointer is byte counter B

are decremented. The cycle is repeated until B e0.

(Note that B is tested for zero after it is decremented. By

loading B initially with zero, 256 data transfers will take

place.)

(HL)

HL b1 Z: Set

Bb1 H: Undefined

Repeat until B e0 P/V: Undefined

N: Set

C: N/A

76543210

11101101

10110010

Timing: For B i0 M cycles Ð 5

T states Ð 21 (4, 5, 3, 4, 5)

For B e0 M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

(Note that after each data transfer cycle, interrupts may be

recognized and two refresh cycles are performed.)

OTDR

Data is output from memory location (HL) to the I/O device

at port address (C), then the HL memory pointer and byte

counter B are decremented. The cycle is repeated until B e

(Note that B is tested for zero after it is decremented. By

loading B initially with zero, 256 data transfers will take

place.)

(C)

(HL) S: Undefined

HL b1 Z: Set

Bb1 H: Undefined

Repeat until B e0 P/V: Undefined

N: Set

C: N/A

76543210

11101101

10111011

Timing: For B i0 M cycles Ð 5

T states Ð 21 (4, 5, 3, 4, 5)

For B e0 M cycles Ð 4

T states Ð 16 (4, 5, 3, 4)

Addressing Mode: Implied/Source Ð Register In-

direct

Destination Ð Register Indirect

(Note that after each data transfer cycle the NSC800 will

accept interrupts and perform two refresh cycles.)

12.13 CPU Control

NOP

The CPU performs no operation.

Ð Ð Ð No flags affected

76543210

00000000

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: N/A

HALT

The CPU halts execution of the program. Dummy op-code

fetches are performed from the next memory location to

keep the refresh circuits active until the CPU is interrupted

or reset from the halted state.

Ð Ð Ð No flags affected

76543210

01110110

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: N/A

Disable system level interrupts.

IFF1

0 No flags affected

IFF2

76543210

11110011

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: N/A

The system level interrupts are enabled. During execution of

this instruction, and the next one, the maskable interrupts

will be disabled.

IFF1

1 No flags affected

IFF2

76543210

11111011

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: N/A

IM 0

The CPU is placed in interrupt mode 0.

Ð Ð Ð No flags affected

76543210

11101101

01000110

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: N/A

12.13 CPU Control (Continued)

IM 1

The CPU is placed in interrupt mode 1.

Ð Ð Ð No flags affected

76543210

11101101

01010110

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: N/A

IM 2

The CPU is placed in interrupt mode 2.

Ð Ð Ð No flags affected

76543210

11101101

01011110

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: N/A

12.14 Program Control

JUMPS

JP nn

Unconditional jump to program location nn.

nn No flags affected

76543210

11000011

n (low-order byte)

n (high-order byte)

Timing: M cycles Ð 3

T states Ð 10 (4, 3, 3)

Addressing Mode: Direct

JP (ss)

Unconditional jump to program location pointed to by regis-

ter ss.

ss No flags affected

76543210

11101001 JP(HL)

Timing: M cycles Ð 1

T states Ð 4

Addressing Mode: Register Indirect

76 5 43210 JP (IX) (for NXe0)

11N

X11101 JP (IY) (for NXe1)

11 1 01001

Timing: M cycles Ð 2

T states Ð 8 (4, 4)

Addressing Mode: Register Indirect

JP cc, nn

Conditionally jump to program location nn based on testable

flag states.

If cc true, No flags affected

nn,

otherwise continue

765 4 3210

11 cc 010

n (low-order byte)

n (high-order byte)

Timing: M cycles Ð 3

T states Ð 10 (4, 3, 3)

Addressing Mode: Direct

JR d

Unconditional jump to program location calculated with re-

spect to the program counter and the displacement d.

PC ad No flags affected

76543210

00011000

Timing: M cycles Ð 3

T states Ð 12 (4, 3, 5)

Addressing Mode: PC Relative

JR kk, d

Conditionally jump to program location calculated with re-

spect to the program counter and the displacement d,

based on limited testable flag states.

If kk true, No flags affected

PC ad,

otherwise continue

76543210

001 kk 000

Timing: if kk met M cycles Ð 3

(true) T states Ð 12 (4, 3, 5)

if kk not met M cycles Ð 2

(not true) T states Ð 7 (4, 3)

Addressing Mode: PC Relative

12.14 Program Control (Continued)

DJNZ d

Decrement the B register and conditionally jump to program

location calculated with respect to the program counter and

the displacement d, based on the contents of the B register.

Bb1 No flags affected

If B e0 continue,

else PC

PC ad

76543210

00010000

Timing: If B i0 M cycles Ð 3

T states Ð 13 (5, 3, 5)

If B e0 M cycles Ð 2

T states Ð 8 (5, 3)

Addressing Mode: PC Relative

CALLS

CALL nn

Unconditional call to subroutine at location nn.

(SP b1)

PCHNo flags affected

(SP b2)

PCL

SP b2

76543210

11001101

n (low-order byte)

n (high-order byte)

Timing: M Cycles Ð 5

T states Ð 17 (4, 3, 4, 3, 3)

Addressing Mode: Direct

CALL cc, nn

Conditional call to subroutine at location nn based on test-

able flag stages.

If cc true, No flags affected

(SP b1)

PCH

(SP b2)

PCL

SP b2

nn,

else continue

765 4 3210

11 cc 100

n (low-order byte)

n (high-order byte)

Timing: If cc true M cycles Ð 5

T states 17 (4, 3, 4, 3, 3)

If cc not true M cycles Ð 3

T states Ð 10 (4, 3, 3)

Addressing Mode: Direct

RETURNS

RET

Unconditional return from subroutine or other return to pro-

gram location pointed to by the top of the stack.

PCL

(SP) No flags affected

PCH

(SP a1)

SP a2

76543210

11001001

Timing: M cycles Ð 3

T states Ð 10 (4, 3, 3)

Addressing Mode: Register Indirect

RET cc

Conditional return from subroutine or other return to pro-

gram location pointed to by the top of the stack.

If cc true, No flags affected

PCL

(SP)

PCH

(SP a1)

SP a2,

else continue

76543210

11 cc 000

Timing: If cc true M cycles Ð 3

T states Ð 11 (5, 3, 3)

If cc not true M cycles Ð 1

T states Ð 5

Addressing Mode: Register Indirect

RETI

Unconditional return from interrupt handling subroutine.

Functionally identical to RET instruction. Unique opcode al-

lows monitoring by external hardware.

PCL

(SP) No flags affected

PCH

(SP a1)

SP a2

76543210

11101101

01001101

Timing: M cycles Ð 4

T states Ð 14 (4, 4, 3, 3)

Addressing Mode: Register Indirect

12.14 Program Control (Continued)

RETN

Unconditional return from non-maskable interrupt handling

subroutine. Functionally similar to RET instruction, except

interrupt enable state is restored to that prior to non-mask-

able interrupt.

PCL

(SP) No flags affected

PCH

(SP a1)

SP a2

IFF1

IFF2

76543210

11101101

01000101

Timing: M cycles Ð 4

T states Ð 14 (4, 4, 3, 3)

Addressing Mode: Register Indirect

RESTARTS

RST P

The present contents of the PC are pushed onto the memo-

ry stack and the PC is loaded with dedicated program loca-

tions as determined by the specific restart executed.

(SP b1)

PCHNo flags affected

(SP b2)

PCL

SP b2

PCH

PCL

76543210

11t111

Timing: M cycles Ð 3

T states Ð 11 (5, 3, 3)

Addressing Mode: Modified Page Zero

p 00H 08H 10H 18H 20H 28H 30H 38H

t 000 001 010 011 100 101 110 111

12.15 Instruction Set: Alphabetical Order

ADC A, (HL) 8E

ADC A, (IXad) DD 8Ed

ADC A, (IYad) FD 8Ed

ADC A, A 8F

ADC A, B 88

ADC A, C 89

ADC A, D 8A

ADC A, E 8B

ADC A, H 8C

ADC A, L 8D

ADC A, n CE n

ADC HL, BC ED 4A

ADC HL, DE ED 5A

ADC HL, HL ED 6A

ADC HL, SP ED 7A

ADD A, (HL) 86

ADD A, (IXad) DD 86d

ADD A, (IYad) FD 86d

ADD A, A 87

ADD A, B 80

ADD A, C 81

ADD A, D 82

ADD A, E 83

ADD A, H 84

ADD A, L 85

ADD A, n C6 n

ADD HL, BC 09

ADD HL, DE 19

ADD HL, HL 29

ADD HL, SP 39

ADD IX, BC DD 09

ADD IX, DE DD 19

ADD IX, IX DD 29

ADD IX, SP DD 39

ADD IY, BC FD 09

ADD IY, DE FD 19

ADD IY, IY FD 29

ADD IY, SP FD 39

AND (HL) A6

AND (IXad) DD A6d

AND (IYad) FD A6d

AND A A7

AND B A0

AND C A1

AND D A2

AND E A3

AND H A4

AND L A5

AND n E6 n

BIT 0, (HL) CB 46

BIT 0, (IXad) DD CBd46

BIT 0, (IYad) FD CBd46

BIT 0, A CB 47

BIT 0, B CB 40

BIT 0, C CB 41

BIT 0, D CB 42

BIT 0, E CB 43

BIT 0, H CB 44

BIT 0, L CB 45

BIT 1, (HL) CB 4E

BIT 1, (IXad) DD CBd4E

BIT 1, (IYad) FD CBd4E

BIT 1, A CB 4F

BIT 1, B CB 48

BIT 1, C CB 49

BIT 1, D CB 4A

BIT 1, E CB 4B

BIT 1, H CB 4C

BIT 1, L CB 4D

BIT 2, (HL) CB 56

BIT 2, (IXad) DD CBd56

BIT 2, (IYad) FD CBd56

BIT 2, A CB 57

BIT 2, B CB 50

BIT 2, C CB 51

BIT 2, D CB 52

BIT 2, E CB 53

BIT 2, H CB 54

BIT 2, L CB 55

BIT 3, (HL) CB 5E

BIT 3, (IXad) DD CBd5E

BIT 3, (IYad) FD CBd5E

BIT 3, A CB 5F

BIT 3, B CB 58

BIT 3, C CB 59

BIT 3, D CB 5A

BIT 3, E CB 5B

BIT 3, H CB 5C

BIT 3, L CB 5D

BIT 4, (HL) CB 66

BIT 4, (IXad) DD CBd66

BIT 4, (IYad) FD CBd66

BIT 4, A CB 67

BIT 4, B CB 60

BIT 4, C CB 61

BIT 4, D CB 62

BIT 4, E CB 63

BIT 4, H CB 64

BIT 4, L CB 65

BIT 5, (HL) CB 6E

BIT 5, (IXad) DD CBd6E

BIT 5, (IYad) FD CBd6E

BIT 5, A CB 6F

BIT 5, B CB 68

BIT 5, C CB 69

BIT 5, D CB 6A

(nn)eaddress of memory location designed displacement

nneData (16 bit) d2edb2

neData (8 bit)

12.15 Instruction Set: Alphabetical Order (Continued)

BIT 5, E CB 6B

BIT 5, H CB 6C

BIT 5, L CB 6D

BIT 6, (HL) CB 76

BIT 6, (IXad) DD CBd76

BIT 6, (IYad) FD CBd76

BIT 6, A CB 77

BIT 6, B CB 70

BIT 6, C CB 71

BIT 6, D CB 72

BIT 6, E CB 73

BIT 6, H CB 74

BIT 6, L CB 75

BIT 7, (HL) CB 7E

BIT 7, (IXad) DD CBd7E

BIT 7, (IYad) FD CBd7E

BIT 7, A CB 7F

BIT 7, B CB 78

BIT 7, C CB 79

BIT 7, D CB 7A

BIT 7, E CB 7B

BIT 7, H CB 7C

BIT 7, L CB 7D

CALL C, nn DCnn

CALL M, nn FCnn

CALL NC, nn D4nn

CALL nn CDnn

CALL NZ, nn C4nn

CALL P, nn F4nn

CALL PE, nn ECnn

CALL PO, nn E4nn

CALL Z, nn CCnn

CCF 3F

CP (HL) BE

CP (IXad) DD BEd

CP (IYad) FD BEd

CP A BF

CP B B8

CP C B9

CP D BA

CP E BB

CP H BC

CP L BD

CP n FE n

CPD ED A9

CPDR ED B9

CPI ED A1

CPIR ED B1

CPL 2F

DAA 27

DEC (HL) 35

DEC (IXad) DD 35d

DEC (IYad) FD 35d

DEC A 3D

DEC B 05

DEC BC 0B

DEC C 0D

DEC D 15

DEC DE 1B

DEC E 1D

DEC H 25

DEC HL 2B

DEC IX DD 2B

DEC IY FD 2B

DEC L 2D

DEC SP 3B

DI F3

DJNZ d2 10 d2

EI FB

EX (SP), HL E3

EX (SP), IX DD E3

EX (SP), IY FD E3

EX AF, A’F’ 08

EX DE, HL EB

EXX D9

HALT 76

IM 0 ED 46

IM 1 ED 56

IM 2 ED 5E

IN A, (C) ED78

IN A, (n) DB n

IN B, (C) ED 40

IN C, (C) ED 48

IN D, (C) ED 50

IN E, (C) ED 58

IN H, (C) ED 60

IN L, (C) ED 68

INC (HL) 34

INC (IXad) DD 34d

INC (IYad) FD 34d

INC A 3C

INC B 04

INC BC 03

INC C 0C

INC D 14

INC DE 13

INC E 1C

INC H 24

INC HL 23

INC IX DD 23

INC IY FD 23

INC L 2C

INC SP 33

IND ED AA

INDR ED BA

INI ED A2

(nn)eAddress of memory location designed displacement

nneData (16 bit) d2edb2

neData (8 bit)

12.15 Instruction Set: Alphabetical Order (Continued)

INIR ED B2

JP (HL) E9

JP (IX) DD E9

JP (IY) FD E9

JP C, nn DAnn

JP M, nn FAnn

JP NC, nn D2nn

JP nn C3nn

JP NZ, nn C2nn

JP P, nn F2nn

JP PE, nn EAnn

JP PO, nn E2nn

JP Z, nn CAnn

JR C, d2 38 d2

JR d2 18 d2

JR NC, d2 30 d2

JR NZ, d2 20 d2

JR Z, d2 28 d2

LD (BC), A 02

LD (DE), A 12

LD (HL), A 77

LD (HL), B 70

LD (HL), C 71

LD (HL), D 72

LD (HL), E 73

LD (HL), H 74

LD (HL), L 75

LD (HL), n 36 n

LD (IXad), A DD 77d

LD (IXad), B DD 70d

LD (IXad), C DD 71d

LD (IXad), D DD 72d

LD (IXad), E DD 73d

LD (IXad), H DD 74d

LD (IXad), L DD 75d

LD (IXad), n DD 36dn

LD (IYad), A FD 77d

LD (IYad), B FD 70d

LD (IYad), C FD 71d

LD (IYad), D FD 72d

LD (IYad), E FD 73d

LD (IYad), H FD 74d

LD (IYad), L FD 75d

LD (IYad), n FD 36dn

LD (nn), A 32nn

LD (nn), BC ED 43nn

LD (nn), DE ED 53nn

LD (nn), HL 22nn

LD (nn), IX DD 22nn

LD (nn), IY FD 22nn

LD (nn), SP ED 73nn

LD A, (BC) 0A

LD A, (DE) 1A

LD A, (HL) 7E

LD A, (IXad) DD 7Ed

LD A, (IYad) FD 7Ed

LD A, (nn) 3Ann

LD A, A 7F

LD A, B 78

LD A, C 79

LD A, D 7A

LD A, E 7B

LD A, H 7C

LD A, I ED 57

LD A, L 7D

LD A, n 3E n

LD B, (HL) 46

LD B, (IXad) DD 46d

LD B, (IYad) FD 46d

LD B, A 47

LD B, B 40

LD B, C 41

LD B, D 42

LD B, E 43

LD B, H 44

LD B, L 45

LD B, n 06 n

LD BC, (nn) ED 4B

LD BC, nn 01nn

LD C, (HL) 4E

LD C, (IXad) DD 4Ed

LD C, (IYad) FD 4Ed

LD C, A 4F

LD C, B 48

LD C, C 49

LD C, D 4A

LD C, E 4B

LD C, H 4C

LD C, L 4D

LD C, n 0E n

LD D, (HL) 56

LD D, (IXad) DD 56d

LD D, (IYad) FD 56d

LD D, A 57

LD D, B 50

LD D, C 51

LD D, D 52

LD D, E 53

LD D, H 54

LD D, L 55

LD D, n 16 n

LD DE, (nn) ED 5Bnn

LD DE, nn 11nn

LD E, (HL) 5E

LD E, (IXad) DD 5Ed

LD E, (IYad) FD 5Ed

(nn)eAddress of memory location designed displacement

nneData (16 bit) d2edb2

neData (8 bit)

12.15 Instruction Set: Alphabetical Order (Continued)

LD E, A 5F

LD E, B 58

LD E, C 59

LD E, D 5A

LD E, E 5B

LD E, H 5C

LD E, L 5D

LD E, n 1E n

LD H, (HL) 66

LD H, (IXad) DD 66d

LD H, (IYad) FD 66d

LD H, A 67

LD H, B 60

LD H, C 61

LD H, D 62

LD H, E 63

LD H, H 64

LD H, L 65

LD H, n 26 n

LD HL, (nn) 2Ann

LD HL, nn 21nn

LD I, A ED 47

LD IX, (nn) DD 2Ann

LD IX, nn DD 21nn

LD IY, (nn) FD 2Ann

LD IY, nn FD 21nn

LD L, (HL) 6E

LD L, (IXad) DD 6Ed

LD L, (IYad) FD 6Ed

LD L, A 6F

LD L, B 68

LD L, C 69

LD L, D 6A

LD L, E 6B

LD L, H 6C

LD L, L 6D

LD L, n 2E n

LD SP, (nn) ED 7Bnn

LD SP, HL F9

LD SP, IX DD F9

LD SP, IY FD F9

LD SP, nn 31nn

LDD ED A8

LDDR ED B8

LDI ED A0

LDIR ED B0

NEG ED n

NOP 00

OR (HL) B6

OR (IXad) DD B6d

OR (IYad) FD B6d

OR A B7

OR B B0

OR C B1

OR D B2

OR E B3

OR H B4

OR L B5

OR n F6 n

OTDR ED BB

OTIR ED B3

OUT (C), A ED 79

OUT (C), B ED 41

OUT (C), C ED 49

OUT (C), D ED 51

OUT (C), E ED 59

OUT (C), H ED 61

OUT (C), L ED 69

OUT n, A D3 n

OUTD ED AB

OUTI ED A3

POP AF F1

POP BC C1

POP DE D1

POP HL E1

POP IX DD E1

POP IY FD E1

PUSH AF F5

PUSH BC C5

PUSH DE D5

PUSH HL E5

PUSH IX DD E5

PUSH IY FD E5

RES 0, (HL) CB 86

RES 0, (IXad) DD CBd86

RES 0, (IYad) FD CBd86

RES 0, A CB 87

RES 0, B CB 80

RES 0, C CB 81

RES 0, D CB 82

RES 0, E CB 83

RES 0, H CB 84

RES 0, L CB 85

RES 1, (HL) CB 8E

RES 1, (IXad) DD CBd8E

RES 1, (IYad) FD CBd8E

RES 1, A CB 8F

RES 1, B CB 88

RES 1, C CB 89

RES 1, D CB 8A

RES 1, E CB 8B

RES 1, H CB 8C

RES 1, L CB 8D

RES 2, (HL) CB 96

RES 2, (IXad) DD CBd96

RES 2, (IYad) FD CBd96

(nn)eAddress of memory location designed displacement

nneData (16 bit) d2edb2

neData (8 bit)

12.15 Instruction Set: Alphabetical Order (Continued)

RES 2, A CB 97

RES 2, B CB 90

RES 2, C CB 91

RES 2, D CB 92

RES 2, E CB 93

RES 2, H CB 94

RES 2, L CB 95

RES 3, (HL) CB 9E

RES 3, (IXad) DD CBd9E

RES 3, (IYad) FD CBd9E

RES 3, A CB 9F

RES 3, B CB 98

RES 3, C CB 99

RES 3, D CB 9A

RES 3, E CB 9B

RES 3, H CB 9C

RES 3, L CB 9D

RES 4, (HL) CB A6

RES 4, (IXad) DD CBdA6

RES 4, (IYad) FD CBdA6

RES 4, A CB A7

RES 4, B CB A0

RES 4, C CB A1

RES 4, D CB A2

RES 4, E CB A3

RES 4, H CB A4

RES 4, L CB A5

RES 5, (HL) CB AE

RES 5, (IXad) DD CBdAE

RES 5, (IYad) FD CBdAE

RES 5, A CB AF

RES 5, B CB A8

RES 5, C CB A9

RES 5, D CB AA

RES 5, E CB AB

RES 5, H CB AC

RES 5, L CB AD

RES 6, (HL) CB B6

RES 6, (IXad) DD CBdB6

RES 6, (IYad) FD CBdB6

RES 6, A CB B7

RES 6, B CB B0

RES 6, C CB B1

RES 6, D CB B2

RES 6, E CB B3

RES 6, H CB B4

RES 6, L CB B5

RES 7, (HL) CB BE

RES 7, (IXad) DD CBdBE

RES 7, (IYad) FD CBdBE

RES 7, A CB BF

RES 7, B CB B8

RES 7, C CB B9

RES 7, D CB BA

RES 7, E CB BB

RES 7, H CB BC

RES 7, L CB BD

RET C9

RET C D8

RET M F8

RET NC D0

RET NZ C0

RET P F0

RET PE E8

RET PO E0

RET Z C8

RETI ED 4D

RETN ED 45

RL (HL) CB 16

RL (IXad) DD CBd16

RL (IYad) FD CBd16

RL A CB 17

RL B CB 10

RL C CB 11

RL D CB 12

RL E CB 13

RL H CB 14

RL L CB 15

RLA 17

RLC (HL) CB 06

RLC (IXad) DD CBd06

RLC (IYad) FD CBd06

RLC A CB 07

RLC B CB 00

RLC C CB 01

RLC D CB 02

RLC E CB 03

RLC H CB 04

RLC L CB 05

RLCA 07

RLD ED 6F

RR (HL) CB 1E

RR (IXad) DD CBd1E

RR (IYad) FD CBd1E

RR A CB 1F

RR B CB 18

RR C CB 19

RR D CB 1A

RR E CB 1B

RR H CB 1C

RR L CB 1D

RRA 1F

RRC (HL) CB OE

RRC (IXad) DD CBd0E

RRC (IYad) FD CBd0E

RRC A CB 0F

(nn)eAddress of memory location designed displacement

nneData (16 bit) d2edb2

neData (8 bit)

12.15 Instruction Set: Alphabetical Order (Continued)

RRC B CB 08

RRC C CB 09

RRC D CB 0A

RRC E CB 0B

RRC H CB 0C

RRC L CB 0D

RRCA 0F

RRD ED 67

RST 0 C7

RST 08H CF

RST 10H D7

RST 18H DF

RST 20H E7

RST 28H EF

RST 30H F7

RST 38H FF

SBC A, (HL) 9E

SBC A, (IXad) DD 9Ed

SBC A, (IYad) FD 9Ed

SBC A, A 9F

SBC A, B 98

SBC A, C 99

SBC A, D 9A

SBC A, E 9B

SBC A, H 9C

SBC A, L 9D

SBC A, n DE n

SBC HL, BC ED 42

SBC HL, DE ED 52

SBC HL, HL ED 62

SBC HL, SP ED 72

SCF 37

SET 0, (HL) CB C6

SET 0, (IXad) DD CBdC6

SET 0, (IYad) FD CBdC6

SET 0, A CB C7

SET 0, B CB C0

SET 0, C CB C1

SET 0, D CB C2

SET 0, E CB C3

SET 0, H CB C4

SET 0, L CB C5

SET 1, (HL) CB CE

SET 1, (IXad) DD CBdCE

SET 1, (IYad) FD CBdCE

SET 1, A CB CF

SET 1, B CB C8

SET 1, C CB C9

SET 1, D CB CA

SET 1, E CB CB

SET 1, H CB CC

SET 1, L CB CD

SET 2, (HL) CB D6

SET 2, (IXad) DD CBdD6

SET 2, (IYad) FD CBdD6

SET 2, A CB D7

SET 2, B CB D0

SET 2, C CB D1

SET 2, D CB D2

SET 2, E CB D3

SET 2, H CB D4

SET 2, L CB D5

SET 3, (HL) CB DE

SET 3, (IXad) DD CBdDE

SET 3, (IYad) FD CBdDE

SET 3, A CB DF

SET 3, B CB D8

SET 3, C CB D9

SET 3, D CB DA

SET 3, E CB DB

SET 3, H CB DC

SET 3, L CB DD

SET 4, (HL) CB E6

SET 4, (IXad) DD CBdE6

SET 4, (IYad) FD CBdE6

SET 4, A CB E7

SET 4, B CB E0

SET 4, C CB E1

SET 4, D CB E2

SET 4, E CB E3

SET 4, H CB E4

SET 4, L CB E5

SET 5, (HL) CB EE

SET 5, (IXad) DD CBdEE

SET 5, (IYad) FD CBdEE

SET 5, A CB EF

SET 5, B CB E8

SET 5, C CB E9

SET 5, D CB EA

SET 5, E CB EB

SET 5, H CB EC

SET 5, L CB ED

SET 6, (HL) CB F6

SET 6, (IXad) DD CBdF6

SET 6, (IYad) FD CBdF6

SET 6, A CB F7

SET 6, B CB F0

SET 6, C CB F1

SET 6, D CB F2

SET 6, E CB F3

SET 6, H CB F4

SET 6, L CB F5

SET 7, (HL) CB FE

SET 7, (IXad) DD CBdFE

SET 7, (IYad) FD CBdFE

SET 7, A CB FF

(nn)eAddress of memory location dedisplacement

nneData (16 bit) d2edb2

neData (8 bit)

12.15 Instruction Set: Alphabetical Order (Continued)

SET 7, B CB F8

SET 7, C CB F9

SET 7, D CB FA

SET 7, E CB FB

SET 7, H CB FC

SET 7, L CB FD

SLA (HL) CB 26

SLA (IXad) DD CBd26

SLA (IYad) FD CBd26

SLA A CB 27

SLA B CB 20

SLA C CB 21

SLA D CB 22

SLA E CB 23

SLA H CB 24

SLA L CB 25

SRA (HL) CB 2E

SRA (IXad) DD CBd2E

SRA (IYad) FD CBd2E

SRA A CB 2F

SRA B CB 28

SRA C CB 29

SRA D CB 2A

SRA E CB 2B

SRA H CB 2C

SRA L CB 2D

SRL (HL) CB 3E

SRL (IXad) DD CBd3E

SRL (IYad) FD CBd3E

SRL A CB 3F

SRL B CB 38

SRL C CB 39

SRL D CB 3A

SRL E CB 3B

SRL H CB 3C

SRL L CB 3D

SUB (HL) 96

SUB (IXad) DD 96d

SUB (IYad) FD 96d

SUB A 97

SUB B 90

SUB C 91

SUB D 92

SUB E 93

SUB H 94

SUB L 95

SUB n D6 n

XOR (HL) AE

XOR (IXad) DD AEd

XOR (IYad) FD AEd

XOR A AF

XOR B A8

XOR C A9

XOR D AA

XOR E AB

XOR H AC

XOR L AD

XOR n EE n

12.16 Instruction Set: Numerical Order

Op Code Mnemonic

00 NOP

01nn LD BC,nn

02 LD (BC),A

03 INC BC

04 INC B

05 DEC B

06n LD B,n

07 RLCA

08 EX AF,A’F’

09 ADD HL,BC

0A LD A,(BC)

0B DEC BC

0C INC C

0D DEC C

0En LD C,n

0F RRCA

10d2 DJNZ d2

11nn LD DE,nn

12 LD (DE),A

13 INC DE

14 INC D

Op Code Mnemonic

15 DEC D

16n LD D,n

17 RLA

18d2 JR d2

19 ADD HL,DE

1A LD A,(DE)

1B DEC DE

1C INC E

1D DEC E

1En LD E,n

1F RRA

20d2 JR NZ,d2

21nn LD HL,nn

22nn LD (nn),HL

23 INC HL

24 INC H

25 DEC H

26n LD H, n

27 DAA

28d2 JR Z,d2

29 ADD HL,HL

Op Code Mnemonic

2Ann LD HL,(nn)

2B DEC HL

2C INC L

2D DEC L

2En LD L,n

2F CPL

30d2 JR NC,d2

31nn LD SP,nn

32nn LD (nn),A

33 INC SP

34 INC (HL)

35 DEC (HL)

36n LD (HL),n

37 SCF

38 JR C,d2

39 ADD HL,SP

3Ann LD A,(nn)

3B DEC SP

3C INC A

3D DEC A

3En LD A,n

(nn)eAddress of memory location dedisplacement

nneData (16 bit) d2edb2

neData (8 bit)

12.16 Instruction Set: Numerical Order (Continued)

Op Code Mnemonic

3F CCF

40 LD B,B

41 LD B,C

42 LD B,D

43 LD B,E

44 LD B,H

45 LD B,L

46 LD B,(HL)

47 LD B,A

48 LD C,B

49 LD C,C

4A LD C,D

4B LD C,E

4C LD C,H

4D LD C,L

4E LD C,(HL)

4F LD C,A

50 LD D,B

51 LD D,C

52 LD D,D

53 LD D,E

54 LD D,H

55 LD D,L

56 LD D,(HL)

57 LD D,A

58 LD E,B

59 LD E,C

5A LD E,D

5B LD E,E

5C LD E,H

5D LD E,L

5E LD E,(HL)

5F LD E,A

60 LD H,B

61 LD H,C

62 LD H,D

63 LD H,E

64 LD H,H

65 LD H,L

66 LD H,(HL)

67 LD H,A

68 LD L,B

69 LD L,C

6A LD L,D

6B LD L,E

6C LD L,H

6D LD L,L

6E LD L,(HL)

6F LD L,A

70 LD (HL),B

71 LD (HL),C

72 LD (HL),D

73 LD (HL),E

Op Code Mnemonic

74 LD (HL),H

75 LD (HL),L

76 HALT

77 LD (HL),A

78 LD A,B

79 LD A,C

7A LD A,D

7B LD A,E

7C LD A,H

7D LD A,L

7E LD A,(HL)

7F LD A,A

80 ADD A,B

81 ADD A,C

82 ADD A,D

83 ADD A,E

84 ADD A,H

85 ADD A,L

86 ADD A,(HL)

87 ADD A,A

88 ADC A,B

89 ADC A,C

8A ADC A,D

8B ADC A,E

8C ADC A,H

8D ADC A,L

8E ADC A,(HL)

8F ADC A,A

90 SUB B

91 SUB C

92 SUB D

93 SUB E

94 SUB H

95 SUB L

96 SUB (HL)

97 SUB A

98 SBC A,B

99 SBC A,C

9A SBC A,D

9B SBC A,E

9C SBC A,H

9D SBC A,L

9E SBC A,(HL)

9F SBC A,A

A0 AND B

A1 AND C

A2 AND D

A3 AND E

A4 AND H

A5 AND L

A6 AND (HL)

A7 AND A

A8 XOR B

Op Code Mnemonic

A9 XOR C

AA XOR D

AB XOR E

AC XOR H

AD XOR L

AE XOR (HL)

AF XOR A

B0 OR B

B1 OR C

B2 OR D

B3 OR E

B4 OR H

B5 OR L

B6 OR (HL)

B7 OR A

B8 CP B

B9 CP C

BA CP D

BB CP E

BC CP H

BD CP L

BE CP (HL)

BF CP A

C0 RET NZ

C1 POP BC

C2nn JP NZ,nn

C3nn JP nn

C4nn CALL NZ,nn

C5 PUSH BC

C6n ADD A,n

C7 RST 0

C8 RET Z

C9 RET

CAnn JP Z,nn

CB00 RLC B

CB01 RLC C

CB02 RLC D

CB03 RLC E

CB04 RLC H

CB05 RLC L

CB06 RLC (HL)

CB07 RLC A

CB08 RRC B

CB09 RRC C

CB0A RRC D

CB0B RRC E

CB0C RRC H

CB0D RRC L

CB0E RRC (HL)

CB0F RRC A

CB10 RL B

CB11 RL C

CB12 RL D

(nn)eAddress of memory location dedisplacement

nneData (16 bit) d2edb2

neData (8-bit)

12.16 Instruction Set: Numerical Order (Continued)

Op Code Mnemonic

CB13 RL E

CB14 RL H

CB15 RL L

CB16 RL (HL)

CB17 RL A

CB18 RR B

CB19 RR C

CB1A RR D

CB1B RR E

CB1C RR H

CB1D RR L

CB1E RR (HL)

CB1F RR A

CB20 SLA B

CB21 SLA C

CB22 SLA D

CB23 SLA E

CB24 SLA H

CB25 SLA L

CB26 SLA (HL)

CB27 SLA A

CB28 SRA B

CB29 SRA C

CB2A SRA D

CB2B SRA E

CB2C SRA H

CB2D SRA L

CB2E SRA (HL)

CB2F SRA A

CB38 SRL B

CB39 SRL C

CB3A SRL D

CB3B SRL E

CB3C SRL H

CB3D SRL L

CB3E SRL (HL)

CB3F SRL A

CB40 BIT 0,B

CB41 BIT 0,C

CB42 BIT 0,D

CB43 BIT 0,E

CB44 BIT 0,H

CB45 BIT 0,L

CB46 BIT 0,(HL)

CB47 BIT 0,A

CB48 BIT 1,B

CB49 BIT 1,C

CB4A BIT 1,D

CB4B BIT 1,E

CB4C BIT 1,H

CB4D BIT 1,L

CB4E BIT 1,(HL)

Op Code Mnemonic

CB4F BIT 1,A

CB50 BIT 2,B

CB51 BIT 2,C

CB52 BIT 2,D

CB53 BIT 2,E

CB54 BIT 2,H

CB55 BIT 2,L

CB56 BIT 2,(HL)

CB57 BIT 2,A

CB58 BIT 3,B

CB59 BIT 3,C

CB5A BIT 3,D

CB5B BIT 3,E

CB5C BIT 3,H

CB5D BIT 3,L

CB5E BIT 3,(HL)

CB5F BIT 3,A

CB60 BIT 4,B

CB61 BIT 4,C

CB62 BIT 4,D

CB63 BIT 4,E

CB64 BIT 4,H

CB65 BIT 4,L

CB66 BIT 4,(HL)

CB67 BIT 4,A

CB68 BIT 5,B

CB69 BIT 5,C

CB6A BIT 5,D

CB6B BIT 5,E

CB6C BIT 5,H

CB6D BIT 5,L

CB6E BIT 5,(HL)

CB6F BIT 5,A

CB70 BIT 6,B

CB71 BIT 6,C

CB72 BIT 6,D

CB73 BIT 6,E

CB74 BIT 6,H

CB75 BIT 6,L

CB76 BIT 6,(HL)

CB77 BIT 6,A

CB78 BIT 7,B

CB79 BIT 7,C

CB7A BIT 7,D

CB7B BIT 7,E

CB7C BIT 7,H

CB7D BIT 7,L

CB7E BIT 7,(HL)

CB7F BIT 7,A

CB80 RES 0,B

CB81 RES 0,C

CB82 RES 0,D

Op Code Mnemonic

CB83 RES 0,E

CB84 RES 0,H

CB85 RES 0,L

CB86 RES 0,(HL)

CB87 RES 0,A

CB88 RES 1,B

CB89 RES 1,C

CB8A RES 1,D

CB8B RES 1,E

CB8C RES 1,H

CB8D RES 1,L

CB8E RES 1,(HL)

CB8F RES 1,A

CB90 RES 2,B

CB91 RES 2,C

CB92 RES 2,D

CB93 RES 2,E

CB94 RES 2,H

CB95 RES 2,L

CB96 RES 2,(HL)

CB97 RES 2,A

CB98 RES 3,B

CB99 RES 3,C

CB9A RES 3,D

CB9B RES 3,E

CB9C RES 3,H

CB9D RES 3,L

CB9E RES 3,(HL)

CB9F RES 3,A

CBA0 RES 4,B

CBA1 RES 4,C

CBA2 RES 4,D

CBA3 RES 4,E

CBA4 RES 4,H

CBA5 RES 4,L

CBA6 RES 4,(HL)

CBA7 RES 4,A

CBA8 RES 5,B

CBA9 RES 5,C

CBAA RES 5,D

CBAB RES 5,E

CBAC RES 5,H

CBAD RES 5,L

CBAE RES 5,(HL)

CBAF RES 5,A

CBB0 RES 6,B

CBB1 RES 6,C

CBB2 RES 6,D

CBB3 RES 6,E

CBB4 RES 6,H

CBB5 RES 6,L

CBB6 RES 6,(HL)

(nn)eAddress of memory location dedisplacement

nneData (16 bit) d2edb2

neData (8-bit)

12.16 Instruction Set: Numerical Order (Continued)

Op Code Mnemonic

CBB7 RES 6,A

CBB8 RES 7,B

CBB9 RES 7,C

CBBA RES 7,D

CBBB RES 7,E

CBBC RES 7,H

CBBD RES 7,L

CBBE RES 7,(HL)

CBBF RES 7,A

CBC0 SET 0,B

CBC1 SET 0,C

CBC2 SET 0,D

CBC3 SET 0,E

CBC4 SET 0,H

CBC5 SET 0,L

CBC6 SET 0,(HL)

CBC7 SET 0,A

CBC8 SET 1,B

CBC9 SET 1,C

CBCA SET 1,D

CBCB SET 1,E

CBCC SET 1,H

CBCD SET 1,L

CBCE SET 1,(HL)

CBCF SET 1,A

CBD0 SET 2,B

CBD1 SET 2,C

CBD2 SET 2,D

CBD3 SET 2,E

CBD4 SET 2,H

CBD5 SET 2,L

CBD6 SET 2,(HL)

CBD7 SET 2,A

CBD8 SET 3,B

CBD9 SET 3,C

CBDA SET 3,D

CBDB SET 3,E

CBDC SET 3,H

CBDD SET 3,L

CBDE SET 3,(HL)

CBDF SET 3,A

CBE0 SET 4,B

CBE1 SET 4,C

CBE2 SET 4,D

CBE3 SET 4,E

CBE4 SET 4,H

CBE5 SET 4,L

CBE6 SET 4,(HL)

CBE7 SET 4,A

CBE8 SET 5,B

CBE9 SET 5,C

CBEA SET 5,D

CBEB SET 5,E

Op Code Mnemonic

CBEC SET 5,H

CBED SET 5,L

CBEE SET 5,(HL)

CBEF SET 5,A

CBF0 SET 6,B

CBF1 SET 6,C

CBF2 SET 6,D

CBF3 SET 6,E

CBF4 SET 6,H

CBF5 SET 6,L

CBF6 SET 6,(HL)

CBF7 SET 6,A

CBF8 SET 7,B

CBF9 SET 7,C

CBFA SET 7,D

CBFB SET 7,E

CBFC SET 7,H

CBFD SET 7,L

CBFE SET 7,(HL)

CBFF SET 7,A

CCnn CALL Z,nn

CDnn CALL nn

CEn ADC A,n

CF RST 8

D0 RET NC

D1 POP DE

D2nn JP NC,nn

D3n OUT (n),A

D4nn CALL NC,nn

D5 PUSH DE

D6n SUB n

D7 RST 10H

D8 RET C

D9 EXX

DAnn JP,C,nn

DBn IN A,(n)

DCnn CALL C,nn

DD09 ADD IX,BC

DD19 ADD IX,DE

DD21nn LD IX,nn

DD22nn LD (nn),IX

DD23 INC IX

DD29 ADD IX,IX

DD2Ann LD IX,(nn)

DD2B DEC IX

DD34d INC (IXad)

DD35d DEC (IXad)

DD36dn LD (IXad),n

DD39 ADD IX,SP

DD46d LD B,(IXad)

DD4Ed LD C,(IXad)

DD56d LD D,(IXad)

DD5Ed LD E,(IXad)

Op Code Mnemonic

DD66d LD H,(IXad)

DD6Ed LD L,(IXad)

DD70d LD (IXad),B

DD71d LD (IXad),C

DD72d LD (IXad),D

DD73d LD (IXad),E

DD74d LD (IXad),H

DD75d LD (IXad),L

DD77d LD (IXad),A

DD7Ed LD A,(IXad)

DD86d ADD A,(IXad)

DD8Ed ADC A,(IXad)

DD96d SUB (IXad)

DD9Ed SBC A,(IXad)

DDA6d AND (IXad)

DDAEd XOR (IXad)

DDB6d OR (IXad)

DDBEd CP (IXad)

DDCBd06 RLC (IXad)

DDCBd0E RRC (IXad)

DDCBd16 RL (IXad)

DDCBd1E RR (IXad)

DDCBd26 SLA (IXad)

DDCBd2E SRA (IXad)

DDCBd3E SRL (IXad)

DDCBd46 BIT 0,(IXad)

DDCBd4E BIT 1,(IXad)

DDCBd56 BIT 2,(IXad)

DDCBd5E BIT 3,(IXad)

DDCBd66 BIT 4,(IXad)

DDCBd6E BIT 5,(IXad)

DDCBd76 BIT 6,(IXad)

DDCBd7E BIT 7,(IXad)

DDCBd86 RES 0,(IXad)

DDCBd8E RES 1,(IXad)

DDCBd96 RES 2,(IXad)

DDCBd9E RES 3,(IXad)

DDCBdA6 RES 4,(IXad)

DDCBdAE RES 5,(IXad)

DDCBdB6 RES 6,(IXad)

DDCBdBE RES 7,(IXad)

DDCBdC6 SET 0,(IXad)

DDCBdCE SET 1,(IXad)

DDCBdD6 SET 2,(IXad)

DDCBdDE SET 3,(IXad)

DDCBdE6 SET 4,(IXad)

DDCBdEE SET 5,(IXad)

DDCBdF6 SET 6,(IXad)

DDCBdFE SET 7,(IXad)

DDE1 POP IX

DDE3 EX (SP),IX

DDE5 PUSH IX

DDE9 JP (IX)

(nn)eAddress of memory location dedisplacement

nneData (16 bit) d2edb2

neData (8-bit)

12.16 Instruction Set: Numerical Order (Continued)

Op Code Mnemonic

DDF9 LD SP,IX

DEn SCB A,n

DF RST 18H

E0 RET PO

E1 POP HL

E2nn JP PO,nn

E3 EX (SP),HL

E4nn CALL PO,nn

E5 PUSH HL

E6n AND n

E7 RST 20H

E8 RET PE

E9 JP (HL)

EAnn JP PE,nn

EB EX DE,HL

ECnn CALL PE,nn

ED40 IN B,(C)

ED41 OUT (C),B

ED42 SBC HL,BC

ED43nn LD (nn),BC

ED44 NEG

ED45 RETN

ED46 IM 0

ED47 LD I,A

ED48 IN C,(C)

ED49 OUT (C),C

ED4A ADC HL,BC

ED4Bnn LD BC,(nn)

ED4D RETI

ED50 IN D,(C)

ED51 OUT (C),D

ED52 SBC HL,DE

ED53nn LD (nn),DE

ED56 IM 1

ED57 LD A,I

ED58 IN E,(C)

ED59 OUT (C), E

ED5A ADC HL,DE

ED5Bnn LD DE,(nn)

ED5E IM 2

ED60 IN H,(C)

ED61 OUT (C),H

ED62 SBC HL,HL

ED67 RRD

ED68 IN L,(C)

ED69 OUT (C),L

ED6A ADC HL,HL

ED6F RLD

ED72 SBC HL,SP

ED73nn LD (nn),SP

ED78 IN A,(C)

ED79 OUT (C),A

ED7A ADC HL,SP

Op Code Mnemonic

ED7Bnn LD SP,(nn)

EDA0 LDI

EDA1 CPI

EDA2 INI

EDA3 OUTI

EDA8 LDD

EDA9 CPD

EDAA IND

EDAB OUTD

EDB0 LDIR

EDB1 CPIR

EDB2 INIR

EDB3 OTIR

EDB8 LDDR

EDB9 CPDR

EDBA INDR

EDBB OTDR

EEn XOR n

EF RST 28H

F0 RET P

F1 POP AF

F2nn JP P,nn

F3 DI

F4nn CALL P,nn

F5 PUSH AF

F6n OR n

F7 RST 30H

F8 RET M

F9 LD SP,HL

FAnn JP M,nn

FB EI

FCnn CALL M,nn

FD09 ADD IY,BC

FD19 ADD IY,DE

FD21nn LD IY,nn

FD22nn LD (nn),IY

FD23 INC IY

FD29 ADD IY,IY

FD2Ann LD IY,(nn)

FD2B DEC IY

FD34d INC (IYad)

FD35d DEC (IYad)

FD36dn LD (IYad),n

FD39 ADD IY,SP

FD46d LD B,(IYad)

FD4Ed LD C,(IYad)

FD56d LD D,(IYad)

FD5Ed LD E,(IYad)

FD66d LD H,(IYad)

FD6Ed LD L,(IYad)

FD70d LD (IYad),B

FD71d LD (IYad),C

FD72d LD (IYad),D

Op Code Mnemonic

FD73d LD (IYad),E

FD74d LD (IYad),H

FD75d LD (IYad),L

FD77d LD (IYad),A

FD7Ed LD A,(IYad)

FD86d ADD A,(IYad)

FD8Ed ADC A,(IYad)

FD96d SUB (IYad)

FD9Ed SBC A,(IYad)

FDA6d AND (IYad)

FDAEd XOR (IYad)

FDB6d OR (IYad)

FDBEd CP (IYad)

FDE1 POP IY

FDE3 EX (SP), IY

FDE5 PUSH IY

FDE9 JP (IY)

FDF9 LD SP,IY

FDCBd06 RLC (IYad)

FDCBd0E RRC (IYad)

FDCBd16 RL (IYad)

FDCBd1E RR (IYad)

FDCBd26 SLA (IYad)

FDCBd2E SRA (IYad)

FDCBd3E SRL (IYad)

FDCBd46 BIT 0,(IYad)

FDCBd4E BIT 1,(IYad)

FDCBd56 BIT 2,(IYad)

FDCBd5E BIT 3,(IYad)

FDCBd66 BIT 4,(IYad)

FDCBd6E BIT 5,(IYad)

FDCBd76 BIT 6,(IYad)

FDCBd7E BIT 7,(IYad)

FDCBd86 RES 0,(IYad)

FDCBd8E RES 1,(IYad)

FDCBd96 RES 2,(IYad)

FDCBd9E RES 3,(IYad)

FDCBdA6 RES 4,(IYad)

FDCBdAE RES 5,(IYad)

FDCBdB6 RES 6,(IYad)

FDCBdBE RES 7,(IYad)

FDCBdC6 SET 0,(IYad)

FDCBdCE SET 1,(IYad)

FDCBdD6 SET 2,(IYad)

FDCBdDE SET 3,(IYad)

FDCBdE6 SET 4,(IYad)

FDCBdEE SET 5,(IYad)

FDCBdF6 SET 6,(IYad)

FDCBdFE SET 7,(IYad)

FEn CP n

FF RST 38H

(nn)eAddress of memory location dedisplacement

nneData (16 bit) d2edb2

neData (8-bit)

13.0 Data Acquisition System

A natural application for the NSC800 is one that requires

remote operation. Since power consumption is low if the

system consists of only CMOS components, the entire

package can conceivably operate from only a battery power

source. In the application described herein, the only source

of power will be from a battery pack composed of a stacked

array of NiCad batteries (see

Figure 20

The application is that of a remote data acquisition system.

Extensive use is made of some of the other LSI CMOS com-

ponents manufactured by National: notably the ADC0816

and MM58167. The ADC0816 is a 16-channel analog-to-

digital converter which operates from a 5V source. The

MM58167 is a microprocessor-compatible real-time clock

(RTC). The schematic for this system is shown in

Figure 20

All the necessary features of the system are contained in six

integrated circuits: NSC800, NSC810A, NSC831, HN6136P,

ADC0816, and MM58167. Some other small scale integra-

tion CMOS components are used for normal interface re-

quirements. To reduce component count, linear selection

techniques are used to generate chip selects for the

NSC810A and NSC831. Included also is a current loop com-

munication link to enable the remote system to transfer data

collected to a host system.

In order to keep component count low and maximize effec-

tiveness, many of the features of the NSC800 family have

been utilized. The RAM section of the NSC810A is used as

a data buffer to store intermediate measurements and as

scratch pad memory for calculations. Both timers contained

in the NSC810A are used to produce the clocks required by

the A/D converter and the RTC. The Power-Save feature of

the NSC800 makes it possible to reduce system power con-

sumption when it is not necessary to collect any data. One

of the analog input channels of the A/D is connected to the

battery pack to enable the CPU to monitor its own voltage

supply and notify the host that a battery change is needed.

In operation, the NSC800 makes readings on various input

conditions through the ADC0816. The type of devices con-

nected to the A/D input depends on the nature of the re-

mote environment. For example, the duties of the remote

system might be to monitor temperature variations in a large

building. In this case, the analog inputs would be connected

to temperature transducers. If the system is situated in a

process control environment, it might be monitoring fluid

flow, temperatures, fluid levels, etc. In either case, operation

would be necessary even if a power failure occurred, thus

the need for battery operation or at least battery backup. At

some fixed times or at some particular time durations, the

system takes readings by selecting one of the analog input

channels, commands the A/D to perform a conversion,

reads the data, and then formats it for transmission; or, the

system checks the readings against set points and trans-

mits a warning if the set points are exceeded. With the addi-

tion of the RTC, the host need not command the remote

system to take these readings each time it is necessary.

The NSC800 could simply set up the RTC to interrupt it at a

previously defined time and when the interrupt occurs, make

the readings. The resultant values could be stored in the

NSC810A for later correlation. In the example of tempera-

ture monitoring in a building, it might be desired to know the

high and low temperatures for a 12-hour period. After com-

piling the information, the system could dump the data to

the host over the communications link. Note from the sche-

matic that the current for the communication link is supplied

by the host to remove the constant current drain from the

battery supply.

The required clocks for the two peripheral devices are gen-

erated by the two timers in the NSC810A. Through the use

of various divisors, the master clock generated by the

NSC800 is divided down to produce the clocks. Four exam-

ples are shown in the table following

Figure 20

All the crystal frequencies are standard frequencies. The

various divisors listed are selected to produce, from the

master clock frequency of the NSC800, an exact 32,768 Hz

clock for the MM58167 and a clock within the operating

range of the A/D converter.

The MM58167 is a programmable real-time clock that is

microprocessor compatible. Its data format is BCD. It allows

the system to program its interrupt register to produce an

interrupt output either on a time of day match (which in-

cludes the day of the week, the date and month) and/or

every month, week, day, hour, minute, second, or tenth of a

second. With this capability added to the system, precise

time of day measurements are possible without having the

CPU do timekeeping. The interrupt output can be connect-

ed, through the use of one port bit of the NSC810A, to put

the CPU in the power-save mode and reenable it at a preset

time. The interrupt output is also connected to one of the

hardware restart inputs (RSTB) to enable time duration

measurements. This power-down mode of operation would

not be possible if the NSC800 had the duties of timekeep-

13.0 Data Acquisition System (Continued)

TL/C/5171–34

FIGURE 20. Remote Data Acquisition

13.0 Data Acquisition System (Continued)

ing. When in the power-save mode, the system power re-

quirements are decreased by about 50%, thus extending

battery life.

Communication with the peripheral devices (MM58167 and

ADC0816) is accomplished through the I/O ports of the

NSC810A and NSC831. The peripheral devices are not con-

nected to the bus of the NSC800 as they are not directly

compatible with a multiplexed bus structure. Therefore, ad-

ditional components would be required to place them on the

microprocessor bus. Writing data into the MM58167 is per-

formed by first putting the desired data on Port A, followed

by selecting the address of the internal register and applying

the chip select through the use of Port B. A bit set and clear

operation is performed to emulate a pulse on the bit of Port

B connected to the WR input of the MM58167. For a read

operation, the same sequence of operations is performed

except that Port A is set for the input mode of operation and

the RD line is pulsed. Similar techniques are used to read

converted data from the A/D converter. When a conversion

is desired, the CPU selects a channel and commands the

ADC0816 to start a conversion. When the conversion is

complete, the converter will produce an End-of-Conversion

signal which is connected to the RSTA interrupt input of the

NSC800.

When operating, the system shown consumes about 125

mw. When in the power-save mode, power consumption is

decreased to about 70 mw. If, as is likely, the system is in

the power-save mode most of the time, battery life can be

quite long depending on the amp-hour rating of the batteries

incorporated into the system. For example, if the battery

pack is rated at 5 amp-hours, the system should be able to

operate for about 400-500 hours before a battery charge or

change is required.

As shown in the schematic (refer to

Figure 20

), analog input

IN0 is connected to the battery source. In this way, the CPU

can monitor its own power source and notify the host that it

needs a battery replacement or charge. Since the battery

source shown is a stacked array of 7 NiCads producing

8.4V, the converter input is connected in the middle so that

it can take a reading on two or three of the cells. Since

NiCad batteries have a relatively constant voltage output

until very nearly discharged, the CPU can sense that the

‘‘knee’’ of the discharge curve has been reached and notify

the host.

Typical Timer Output Frequencies

Crystal Frequency CPU Clock Output Timer 0 Output Timer 1 Output

2.097152 MHz 1.048576 MHz 262.144 kHz 32.768 kHz

divisor e4 divisor e8

3.276800 MHz 1.638400 MHz 327.680 kHz 32.768 kHz

divisor e5 divisor e10

4.194304 MHz 2.097152 MHz 262.144 kHz 32.768 kHz

divisor e8 divisor e8

4.915200 MHz 2.457600 MHz 491.520 kHz 32.768 kHz

divisor e5 divisor e15

14.0 NSC800M/883B MIL-STD-833

Class C Screening

National Semiconductor offers the NSC800D and NSC800E

with full class B screening per MIL-STD-883 for Military/

Aerospace programs requiring high reliability. In addition,

this screening is available for all of the key NSC800 periph-

eral devices.

Electrical testing is performed in accordance with

RESTS800X, which tests or guarantees all of the electrical

performance characteristics of the NSC800 data sheet. A

copy of the current revision of RETS800X is available upon

request.

100% Screening Flow

Test MIL-STD-883 Method/Condition Requirement

Internal Visual 2010B 100%

Stabilization Bake 1008 C 24 Hrs. @a150§C 100%

Temperature Cycling 1010 C 10 Cycles b65§C/a150§C 100%

Constant Acceleration 2001 E 30,000 G’s, Y1 Axis 100%

Fine Leak 1014 A or B 100%

Gross Leak 1014C 100%

Burn-In 1015 160 Hrs. @a125§C (using 100%

burn-in circuits shown below)

Final Electrical a25§C DC per RETS800X 100%

PDA 10% Max

a125§C AC and DC per RETS800X 100%

b55§C AC and DC per RETS800X 100%

a25§C AC per RETS800X 100%

QA Acceptance 5005 Sample Per

Quality Conformance Method 5005

External Visual 2009 100%

15.0 Burn-In Circuits

5240HR

NSC800D/883B (Dual-In-Line)

TL/C/5171–32

Top View

5241HR

NSC800E/883B (Leadless Chip Carrier)

TL/C/5171–33

All resistors 2.7 kXunless marked otherwise.

Note 1: All resistors are (/4Wg5% unless otherwise specified.

Note 2: All clocks 0V to 3V, 50% duty cycle, in phase with k1ms rise and fall time.

Note 3: Device to be cooled down under power after burn-in.

16.0 Ordering Information

NSC800 XXXX

/AaeA

aReliability Screening

/883 eMIL-STD-883 Screening (Note 1)

IeIndustrial Temperature (b40§Ctoa

85§C)

MeMilitary Temperature (b55§Ctoa

125§C)

MIL eSpecial Temperature (b55§Ctoa

90§C)

No Designation eCommercial Temperature (0§Ctoa

70§C)

b4e4 MHz Clock

b35 e3.5 MHz Clock Output

b3e2.5 MHz Clock Output

b1e1 MHz Clock Output

DeCeramic Package

NePlastic Package

EeCeramic Leadless Chip Carrier (LCC)

VePlastic Leaded Chip Carrier (PCC)

Note 1: Do not specify a temperature option; all parts are screened to military temperature.

17.0 Reliability Information

Gate Count 2750

Transistor Count 11,000

Physical Dimensions inches (millimeters)

Molded Dual-In-Line Package (N)

Order Number NSC800N

NS Package Number N40A

Hermetic Dual-In-Line Package (D)

Order Number NSC800D

NS Package Number D40C

Physical Dimensions inches (millimeters) (Continued)

Leadless Chip Carrier Package (E)

Order Number NSC800E

NS Package Number E44A

Physical Dimensions inches (millimeters) (Continued)

NSC800 High-Performance Low-Power CMOS Microprocessor

Plastic Chip Carrier (V)

Order Number NSC800V

NS Package Number V44A

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT

DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL

SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or 2. A critical component is any component of a life

systems which, (a) are intended for surgical implant support device or system whose failure to perform can

into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life

failure to perform, when properly used in accordance support device or system, or to affect its safety or

with instructions for use provided in the labeling, can effectiveness.

be reasonably expected to result in a significant injury

to the user.

National Semiconductor National Semiconductor National Semiconductor National Semiconductor

Corporation Europe Hong Kong Ltd. Japan Ltd.

1111 West Bardin Road Fax: (

49) 0-180-530 85 86 13th Floor, Straight Block, Tel: 81-043-299-2309

Arlington, TX 76017 Email: cnjwge

tevm2.nsc.com Ocean Centre, 5 Canton Rd. Fax: 81-043-299-2408

Tel: 1(800) 272-9959 Deutsch Tel: (

49) 0-180-530 85 85 Tsimshatsui, Kowloon

Fax: 1(800) 737-7018 English Tel: (

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49) 0-180-532 93 58 Tel: (852) 2737-1600

Italiano Tel: (

49) 0-180-534 16 80 Fax: (852) 2736-9960

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.