Zilog Z80380 User Manual

DC-8297-03

PREFACE

Thank you for your interest in the Z380

™

Central Processing Unit (CPU) and its

associated family of products. This Technical Manual describes programming

and operation of the Z380

™

Superintegration

™

Core CPU, which is found in the

Z380 Microprocessor Unit (MPU), and products built around Z380

™

CPU core.

This Z380 User's Manual consists of the following Sections:

1. Z380

™

Architectural Overview

Chapter 1 is an introductory section covering the key features and

giving an overview of the architecture of the device.

2. Address Spaces

Chapter 2 explains the address spaces the Z380 CPU can handle.

Also, this chapter includes a brief description of the on-chip regis-

ters.

3. Native/Extended Mode, Word/Long Word Mode of Operation,

and Decoder Directives

This chapter provides a detailed explanation on the Z380’s unique

features, operation modes, and the Decoder Directives.

4. Addressing Modes and Data Types

Chapter 4 describes the Addressing mode and data types which the

Z380 can handle.

5. Instruction Set

Chapter 5 contains an overview of the instruction set; as well as a

detailed instruction-by-instruction description in alphabetical order.

6. Interrupts and Traps

Chapter 6 explains the interrupts and traps features of the Z380.

7. Reset

Chapter 7 describes the Reset function.

8. Z380 Benchmark Appnote

9. Z380 Questions & Answers

Z80380 CPU

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Appendix A

Appendix A covers the Z380’s instruction format.

Appendix B

Appendix B contains all Z380 instructions sorted in Alphabetical

Order.

Appendix C

Appendix C contains all Z380 instructions sorted in Numerical

Order.

Appendix D

The Tables in Appendix D lists all the Z380 instructions in instruction

affected by Native/Extended mode and Word/Long Word mode.

Appendix E

The Tables in Appendix E lists all the Z380 instructions in instruction

affected by DDIR IM (Immediate Decoder Directives) mode.

Index

A to Z listing of Z380

™

User's Manual key words and phrases.

This manual assumes the reader has a basic knowledge of CPU-

based system architectures and software development systems,

such as the use of the text editor, and invoking the assembler/

compiler. Also, knowledge of the Z80

®

CPU architecture is desirable.

Zilog’s products are not authorized for use as critical compo-

nents in life support devices or systems unless a specific written

agreement pertaining to such intended use is executed between

the customer and Zilog prior to use. Life support devices or

systems are those which are intended for surgical implantation

into the body, or which sustains life whose failure to perform,

when properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result in

significant injury to the user.

Zilog, Inc. 210 East Hacienda Ave.

Campbell, CA 95008-6600

Telephone [phone]

Telex 910-338-7621

FAX [phone]

Internet: http://www.zilog.com

© 1994, 1995, 1996, 1997 by Zilog, Inc. All rights reserved. No

part of this document may be copied or reproduced in any form

or by any means without the prior written consent of Zilog, Inc.

The information in this document is subject to change without

notice. Devices sold by Zilog, Inc. are covered by warranty and

patent indemnification provisions appearing in Zilog, Inc. Terms

and Conditions of Sale only.

ZILOG, INC. MAKES NO WARRANTY, EXPRESS, STATUTORY,

IMPLIED OR BY DESCRIPTION, REGARDING THE INFORMA-

TION SET FORTH HEREIN OR REGARDING THE FREEDOM OF

THE DESCRIBED DEVICES FROM INTELLECTUAL PROPERTY

INFRINGEMENT. ZILOG, INC. MAKES NO WARRANTY OF MER-

CHANTABILITY OR FITNESS FOR ANY PURPOSE.

Zilog, Inc. shall not be responsible for any errors that may appear

in this document. Zilog, Inc. makes no commitment to update or

keep current the information contained in this document.

U

SER

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ILOG

1.1 INTRODUCTION

USER’s MANUAL

CHAPTER 1

Z380

™

ARCHITECTURAL OVERVIEW

The Z380 CPU incorporates advanced architectural fea-

tures that allow fast and efficient throughput and increased

memory addressing capabilities while maintaining Z80

®

CPU and Z180

®

MPU object-code compatibility. The Z380

CPU core provides a continuing growth path for present

Z80- or Z180

®

-based designs and offers the following key

features:

■ Full Static CMOS Design with Low Power Standby

Mode Support

■ DC to 18 MHz Operating Frequency @ 5 Volts V

CC

■ DC to 10 MHz Operating Frequency @ 33 Volts V

CC

■ Enhanced Instruction Set that Maintains Object-Code

Compatibility with Z80 and Z180 Microprocessors

■ 16-Bit (64K) or 32-Bit (4G) Linear Address Space

■ 16-Bit Internal Data Bus

■ Two Clock Cycle Instruction Execution (Minimum)

■ Multiple On-Chip Register Files (Z380 MPU has Four

Banks)

■ BC/DE/HL/IX/IY Registers are Augmented by 16-Bit

Extended Registers (BCz/DEz/HLz/IXz/IYz), PC/SP/I

Registers are Augmented by Extended Registers (PCz/

SPz/Iz) for 32-Bit Addressing Capability.

■ Newly Added IX’ and IY’ Registers with Extended

Registers (IXz’/IYz’)

■ Enhanced Interrupt Capabilities, Including 16-Bit

Vector

■ Undefined Opcode Trap for Full Z380 CPU Instruction

Set

The Z380 CPU, an enhanced version of the Z80 CPU,

retains the Z80 CPU instruction set to maintain complete

binary-code compatiblity with present Z80 and Z180 codes.

The basic addressing modes of the Z80 microprocessor

have been augmented with Stack Pointer Relative loads

and stores, 16-bit and 24-bit Indexed offsets, and in-

creased Indirect register addressing flexibility, with all of

the addressing modes allowing access to the entire 32-bit

address space. Significant additions have been made to

the instruction set iincorporating16-bit arithmetic and logi-

cal operations, 16-bit I/O operations, multiply and divide,

a complete set of register-to-register loads and exchanges,

plus 32-bit load and exchange, and 32-bit arithmetic

operation for address calculation.

The basic register file of the Z80 microprocessor is ex-

panded to include alternate register versions of the IX and

IY registers. There are four sets of this basic Z80 micropro-

cessor register file present in the Z380 MPU, along with the

necessary resources to manage switching between the

different register sets. All of the register pairs and index

registers in the basic Z80 microprocessor register file are

expanded to 32 bits.

The Z380 CPU expands the basic 64 Kbyte Z80 and Z180

address space to a full 4 Gbyte (32-bit) address space.

This address space is linear and completely accessible to

the user program. The external I/O address space is

similarly expanded to a full 4 Gbyte (32-bit) range, and 16-

bit I/O, both simple and block move are included. A 256

byte-wide internal I/O space has been added. This space

will be used to access on-chip I/O resources on future

Superintegration implementation of this CPU core.

Figure 1-1 provides a detailed description of the basic

register architecture of the Z380 CPU with the size of the

register banks shown at four each, however, the Z380 CPU

architecture allows future expansion of up to 128 sets of

each.

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1.1 INTRODUCTION (Continued)

AF

BC

DE

HL

IXU IXL

IYU IYL

A' F'

B' C'

D' E'

H' L'

IXU' IXL'

IYU' IYL'

BCz'

DEz'

HLz'

IXz'

IYz'

BCz

DEz

HLz

IXz

IYz

R

I

SPz

PCz

Iz

SP

PC

4 Sets of Registers

Figure 1-1. Z380

™

CPU Register Architecture

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1.2 CPU ARCHITECTURE

The Z380 CPU is a binary-compatible extension of the Z80

CPU and the Z180 CPU architecture. High throughput

rates are achieved by a high clock rate, high bus band-

width, and instruction fetch/execute overlap. Communi-

cating to the external world through an 8-bit or 16-bit data

bus, the Z380 CPU is a full 32-bit machine internally, with

a 32-bit ALU and 32-bit registers.

1.2.1 Modes of Operation

To maintain compatibility with the Z80/Z180 CPU while

having the capability to manipulate 4 Gbytes of memory

address range, the Z380 CPU has two bits in the Select

Register (SR) to control the modes of operation. One bit

controls the address manipulation mode: Native mode or

Extended mode; and the other bit controls the data ma-

nipulation mode: Word mode or Long Word mode. In

result, the Z380 CPU has four modes of operation. On

reset, the Z380 CPU is in Native/Word mode, which is

compatible to the Z80/Z180’s operation mode. For details

on this subject, refer to Chapter 3, “Native/Extended Mode,

Word/Long Word Mode of Operation, and Decoder Direc-

tive Instructions.”

1.2.1.1 Native Mode and Extended Mode

The Z380 CPU can operate in either Native or Extended

mode, as controlled by a bit in the Select Register (SR). In

Native mode (the Reset configuration), all address ma-

nipulations are performed modulo 65536 (2

16

). In this

mode, the Program Counter (PC) only increments across

16 bits, all address manipulation instructions (increment,

decrement, add, subtract, indexed, stack relative, and PC

relative) only operate on 16 bits, and the Stack Pointer (SP)

only increments and decrements across 16 bits. The PC

high-order word is left at all zeros, as the high-order words

of the SP and the I register. Thus, Native mode is fully

compatible with the Z80 CPU’s 64 Kbyte address mode. It

is still possible to address memory outside of 64 Kbyte

address space for data storage and retrieval in Native

mode, however, since direct addresses, indirect addresses,

and the high-order word of the SP, I, and the IX and IY

registers may be loaded with non-zero values. Executed

code and interrupt service routines must reside in the

lowest 64 Kbytes of the address space.

In Extended mode, however, all address manipulation

instructions operate on 32 bits, allowing access to the

entire 4 Gbyte address space of the Z380 CPU. In both

Native and Extended modes, the Z380 drives all 32 bits of

the address onto the external address bus; only the width

of the manipulated addresses distinguishes Native from

Extended mode. The Z380 CPU implements one instruc-

tion to allow switching from Native to Extended mode

(SETC XM); however, once in Extended mode, only Reset

will return the Z380 CPU to Native mode. This restriction

applies because of the possibility of “misplacing” interrupt

service routines or vector tables during the transition from

Extended mode back to Native mode.

1.2.1.2 Word or Long Word Mode

In addition to Native and Extended mode, which are

specific to memory space addressing, the Z380 CPU can

operate in either Word or Long Word mode specific to data

load and exchange operations. In Word mode (the Reset

configuration), all word load and exchange operations

manipulate 16-bit quantities. For example, only the low-

order words of the source and destination are exchanged

in an exchange operation, with the high-order words

unaffected.

In the Long Word mode, all 32 bits of the source and

destination are exchanged. The Z380 CPU implements

two instructions plus decoder directives to allow switching

between Word and Long Word mode; SETC LW (Set

Control Long Word) and RESC LW (Reset Control Long

Word) perform a global switch, while DDIR W, DDIR LW

and their variants are decoder directives that select a

particular mode only for the instruction that they precede.

Note that all word data arithmetic (as opposed to address

manipulation arithmetic), rotate, shift, and logical opera-

tions are always in 16-bit quantities. They are not con-

trolled by either the Native/Extended or Word/Long Word

selections. The exceptions to the 16-bit quantities are, of

course, those multiply and divide operations with 32-bit

products or dividends.

All word Input/Output operations are performed on 16-bit

values, regardless of Word/Long Word operation.

1.2.2 Address Spaces

Addressing spaces in the Z380 CPU include the CPU

register, the CPU control register, the memory address,

on-chip I/O address, and the external I/O address. The

CPU register space is a superset of the Z80 CPU register

set, and consists of all of the registers in the CPU register

file. These CPU registers are used for data and address

manipulation, and are an extension of the Z80 CPU register

set, with four sets of this extended Z80 CPU register set

present in the Z380 CPU. Access to these registers is

specified in the instruction, with the active register set

selected by bits in the Select Register (SR) in the CPU

control register space.

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1.2.2 Address Spaces (Continued)

Each register set includes the primary registers A, F, B, C,

D, E, H, L, IX, and IY, as well as the alternate registers A’,

F’, B’, C’, D’, E’, H’, L’, IX’, and IY’. Also, IX, IX’, IY, and IY’

registers are accessible as two byte registers, each named

as IXU, IXL, IXU’ IXL’, IYU, IYL, IYU’, and IYL’. These byte

registers can be paired B with C, D with E, H with L, B’ with

C’, D’ with E’, and H’ with L’ to form word registers, and

these word registers are extended to 32 bits with the “z”

extension to the register. This register extension is only

accessible when using the register as a 32-bit register (in

the Long Word mode) or when swapping between the

most-significant and least-significant word of a 32-bit

register using SWAP instructions. Whenever an instruction

refers to a word register, the implicit size is controlled by

Word or Long Word mode. Also included are the R, I, and

SP registers, as well as the PC.

The Select Register (SR) determines the operation of the

Z380 CPU. The contents of this register determine the CPU

operating mode, which register bank will be used, the

interrupt mode in effect, and so on.

The Z380 CPU’s memory address space is linear 4 Gbytes.

To keep compatibility with the Z80 CPU memory address-

ing model, it has two control bits to change its operation

modes—Native or Extended, Word or Long Word.

The Z380 CPU architecture also distinguishes between

the memory and I/O addressing space and, therefore,

requires specific I/O instructions. Furthermore, I/O ad-

dressing space is subdivided into the on-chip I/O address

space and the external I/O addressing space. External

I/O addressing space in the Z380 CPU is 32 bits long, and

internal I/O addressing space is 8-bits long. There are

separate sets of I/O instructions for each I/O addressing

space.

Some of the Internal I/O registers are used to control the

functionality of the device, such as to program/read status

of Trap, Assigned Vector Base address, enabling of inter-

rupts, and to get Chip version ID.

For details on this topic, refer to Chapter 2, “Address

Spaces.”

1.2.3 Data Types

Many data types are supported by the Z380 CPU architec-

ture. The basic data type is the 8-bit byte, which is also the

basic addressable memory element. The architecture also

supports operations on bits, BCD (Binary Coded Decimal)

digits, words (16 bits or 32 bits), byte strings and word

strings. For details on this topic, refer to Section 4.3, “Data

Types.”

1.2.4. Addressing Modes

Addressing modes are used by the Z380 CPU to calculate

the effective address of an operand needed for execution

of an instruction. Seven addressing modes are supported

by the Z380 CPU. Of these seven, one is an addition to the

Z80 CPU addressing modes (Stack Pointer Relative) and

the remaining six modes are either existing or extensions

to Z80 CPU addressing modes.

■ Register

■ Immediate

■ Indirect Register

■ Direct Address

■ Indexed

■ Program Counter Relative

■ Stack Pointer Relative

All addressing modes are available on the 8-bit load,

arithmetic, and logical instructions; the 8-bit shift, rotate,

and bit manipulation instructions are limited to the regis-

ters and Indirect register addressing modes. The 16-bit

loads on the addressing registers support all addressing

modes except Index, while other 16-bit operations are

limited to the Register, Immediate, Indirect Register, In-

dex, Direct Address, and PC Relative addressing modes.

For details on this subject, refer to Chapter 4, “Addressing

Modes and Data Types.”

1.2.5. Instruction Set

The Z380 CPU instruction set is an expansion of the Z80

instruction set; the enhancements include support for

additional addressing modes for the Z80 instructions as

well as the addition of new instructions. The Z380 CPU

instruction set provides a full complement of 8-bit, 16-bit,

and 32-bit operation, including multiplication and division.

For details on this subject, refer to Chapter 5, “Instruction

Set.”

1.2.6 Exception Conditions

The Z380 CPU supports three types of exceptions (condi-

tions that alter the normal flow of program execution);

interrupts, traps, and resets.

Interrupts are asynchronous events typically triggered by

peripherals requiring attention. The Z380 CPU interrupt

structure has been significantly enhanced by increasing

the number of interrupt request lines and by adding an

efficient means for handling nested interrupts. The Z380

CPU has five interrupt lines. These are: Nonmaskable

Interrupt line (/NMI) and Maskable interrupt lines (/INT0,

/INT1, /INT2, and /INT3). Interrupt requests on /INT3-/INT1

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are handled by a newly added interrupt handing mode,

“Assigned Vectored Mode,” which is a fixed vectored

interrupt mode similar in interrupt handling to the Z180’s

interrupts from on-chip peripherals. For handling interrupt

requests on the /INT0 line, there are four modes available:

■ 8080 compatible (Mode 0), in which the interrupting

device provides the first instruction of the interrupt

routine.

■ Dedicated interrupts (Mode 1), in which the CPU

jumps to a dedicated address when an interrupt

occurs.

■ Vectored interrupt mode (Mode 2), in which the

interrupting peripheral device provides a vector into a

table of jump address.

■ Enhanced vectored interrupt mode (Mode 3), wherein

the CPU expects 16-bit vector, instead of 8-bit interrupt

vectors in Mode 2.

The first three modes are compatible with Z80 interrupt

modes; the fourth mode provides more flexibility.

Traps are synchronous events that trigger a special CPU

response when an undefined instruction is executed. It

can be used to increase system reliability, or used as a

“software trap instruction.”

Hardware resets occur when the /RESET line is activated

and override all other conditions. A /RESET causes certain

CPU control registers to be initialized.

For details on this subject, refer to Chapter 6, “Interrupts

and Traps.”

1.3 BENEFITS OF THE ARCHITECTURE

The Z380 CPU architecture provides several significant

benefits, including increased program throughput achieved

by higher bus bandwidth (16-bit wide bus), reduction to

two clocks/basic machine cycle (vs four clocks/cycle on

the Z80 CPU), prefetch cue, access to the larger linear

addressing space, enhanced instructions/new address-

ing mode, data/address manipulation in 16/32 bits, and

faster context switching by utilizing multiple register banks.

1.3.1 High Throughput

Very high throughput rates can be achieved with the Z380

CPU, due to the basic machine cycle’s reduction to two

clocks/cycle from four clocks/cycle on the Z80 CPU, fine

tuned four staged pipeline with prefetch cue. This well

designed pipeline and prefetch cue are both totally trans-

parent to the user, thus maximizing the efficiency of the

pipeline all the time. The Z380 CPU implemented onto the

Z380 MPU is configured with a 16-bit wide data bus, which

doubles the bus bandwidth. These architectural features

result in two clocks/instructions execution minimum, three

clocks/instruction on average. The high clock rates (up to

40 MHz) achievable with this processor. Make the overall

performance of the Z380 CPU more than ten times that of

the Z80.

1.3.2 Linear Memory Address Space

Z380 CPU architecture has 4 Gbytes of linear memory

address space. The Z80 CPU architecture allows 64

Kbytes of memory addressing space. This was more than

sufficient when the Z80 CPU was first developed. But as

the technology improved over time, applications started to

demand more complicated processing, multitasking, faster

processing, etc., with the high level language needed to

develop software. As a result, 64 Kbytes of memory ad-

dressing space is not enough for some Z80 CPU based

applications. In order to handle more than 64 Kbytes of

memory, the Z80 CPU requires a Memory Banking scheme,

or MMU (Memory Management Unit), like the Z180 MPU or

Z280 MPU. These provide the overhead to access more

than 64 Kbytes of memory.

The Z380 CPU architecture allows access to a full 4 Gbytes

(2

32

) of memory addressing space as well as 4 Gbytes of

I/O addressing area, without using a Memory Banking

scheme, or MMU.

1.3.3. Enhanced Instruction Set with 16-Bit

and 32-Bit Manipulation Capability

The Z380 CPU instruction set is 100% upward compatible

to the Z80 CPU instruction set; that is all the Z80 instruc-

tions have been preserved at the binary level. New instruc-

tions added to the Z380 CPU include:

■ Less restricted operand source/destination

combinations.

■ More flexible register exchange instructions.

■ Stack Pointer Relative addressing mode.

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1.3.3. Enhanced Instruction Set with 16-Bit

and 32-Bit Manipulation Capability

(Continued)

■ DDIR (Decoder Directive Instructions) to enhance

addressing capability to cover 4 Gbytes of memory

space, as well as data manipulation capability.

■ Jump relative/Call relative instructions with 8-bit,

16-bit, or 24-bit displacement.

■ Full complements of 16-bit arithmetic instructions.

■ 32-bit manipulate instructions for address manipulation.

These new instructions help to compact the code, as well

as shorten the program’s overall execution speed.

For details on this subject, refer to Chapter 5, “Instruction

Set.”

1.3.4 Faster Context Switching

The Z380 CPU architecture allows multiple sets of register

banks for AF/AF’, BC/DE/HL, BC’/DE’/HL’, IX/IX’, IY/IY’

register pairs (including each register's Extended portion).

When doing context switching, by exceptional condition

(trap or interrupts) or by subroutine/procedure calls, the

CPU has to save the contents of the registers currently in

use, along with the current CPU status.

Traditionally in the Z80 CPU architecture, this is done by

saving the contents of the register into memory, usually

using push/pop instructions or the auxiliary register file.

Register contents are then restored when the process is

finished.

With the Z380 CPU’s multiple register banks, saving the

contents of the working register set currently in use is just

a matter of an instruction to change the field in the Select

Register, which allows fast context switching.

1.4 SUMMARY

The Z380 CPU is a high-performance 16-bit Central Pro-

cessing Unit Superintegration

™

core. Code-compatible

with the Z80 CPU, the Z380 CPU architecture has been

expanded to include features such as multiple register

banks, 4 Gbytes of linear memory addressing space, and

efficient handling of nested interrupts. The benefits of this

architecture, including high throughput rates, code den-

sity, and compiler efficiency, greatly enhance the power

and versatility of the Z380 CPU. Thus, the Z380 CPU

provides both a growth path for existing Z80-based de-

signs and a powerful processor for applications and the

products to be developed around this CPU core.

Zilog’s products are not authorized for use as critical compo-

nents in life support devices or systems unless a specific written

agreement pertaining to such intended use is executed between

the customer and Zilog prior to use. Life support devices or

systems are those which are intended for surgical implantation

into the body, or which sustains life whose failure to perform,

when properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result in

significant injury to the user.

Zilog, Inc. 210 East Hacienda Ave.

Campbell, CA 95008-6600

Telephone [phone]

Telex 910-338-7621

FAX [phone]

Internet: http://www.zilog.com

© 1994, 1995, 1996, 1997 by Zilog, Inc. All rights reserved. No

part of this document may be copied or reproduced in any form

or by any means without the prior written consent of Zilog, Inc.

The information in this document is subject to change without

notice. Devices sold by Zilog, Inc. are covered by warranty and

patent indemnification provisions appearing in Zilog, Inc. Terms

and Conditions of Sale only.

ZILOG, INC. MAKES NO WARRANTY, EXPRESS, STATUTORY,

IMPLIED OR BY DESCRIPTION, REGARDING THE INFORMA-

TION SET FORTH HEREIN OR REGARDING THE FREEDOM OF

THE DESCRIBED DEVICES FROM INTELLECTUAL PROPERTY

INFRINGEMENT. ZILOG, INC. MAKES NO WARRANTY OF MER-

CHANTABILITY OR FITNESS FOR ANY PURPOSE.

Zilog, Inc. shall not be responsible for any errors that may appear

in this document. Zilog, Inc. makes no commitment to update or

keep current the information contained in this document.

2-1

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2.1 INTRODUCTION

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CHAPTER 2

ADDRESS SPACES

The Z380 CPU supports five address spaces correspond-

ing to the different types of locations that can be ad-

dressed and the method by which the logical addresses

are formed. These five address spaces are:

■ CPU Register Space. This consists of all the register

addresses in the CPU register file.

■ CPU Control Register Space. This consists of the

Select Register (SR).

■ Memory Address Space. This consists of the

addresses of all locations in the main memory.

2.2 CPU REGISTER SPACE

The Z380 register file is illustrated in Figure 2-1. Note that

this figure shows the configuration of the register on the

Z380 CPU, and the number of the register files may vary on

future Superintegration devices. The Z380 CPU contains

abundant register resources. At any given time, the pro-

gram has immediate access to both primary and alternate

registers in the selected register set. Changing register

sets is a simple matter of an LDCTL instruction to program

the Select Register (SR).

The CPU register file is divided into five groups of registers

(an apostrophe indicates a register in the auxiliary regis-

ters).

■ Four sets of Flag and Accumulator registers (F, A, F’,

A’)

■ Four sets of Primary and Working registers (B, C, D, E,

H, L, B’, C’, D’, E’, H’, L’)

■ External I/O Address Space. This consists of all

external I/O ports addresses through which peripheral

devices are accessed.

■ On-Chip I/O Address Space. This consists of all

internal I/O port addresses through which peripheral

devices are accessed. Also, this addressing space

contains registers to control the functionality of the

device, giving status information.

■ Four sets of Index registers (IX, IY, IX’, IY’)

■ Stack Pointer (SP)

■ Program Counter, Interrupt register, Refresh register

(PC, I, R)

Register addresses are either specified explicitly in the

instruction or are implied by the semantics of the instruc-

tion.

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2.2 CPU REGISTER SPACE (Continued)

AF

BC

DE

HL

IXU IXL

IYU IYL

A' F'

B' C'

D' E'

H' L'

IXU' IXL'

IYU' IYL'

BCz'

DEz'

HLz'

IXz'

IYz'

BCz

DEz

HLz

IXz

IYz

R

I

SPz

PCz

Iz

SP

PC

4 Sets of Registers

Figure 2-1. Register File Organization (Z380 MPU)

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2.2.1 Primary and Working Registers

The working register set is divided into two register files:

the primary file and the alternate file (designated by prime

(‘)). Each file contains an 8-bit accumulator (A), a Flag

register (F), and six 8-bit general-purpose registers (B, C,

D, E, H, and L) with their Extended registers. Only one file

can be active at any given time, although data in the

inactive file can still be accessed by using EX R, R’

instructions for the byte-wide registers, EX RR, RR’ instruc-

tions for register pairs (either in 16-bit or 32-bit wide

depending on the LW status). Exchange instructions allow

the programmer to exchange the active file with the inac-

tive file. The EX AF, AF’, EXX, or EXALL instructions

changes the register files in use. Upon reset, the primary

register file in register set 0 is active. Changing register

sets is a simple matter of an LDCTL instruction to program

SR.

The accumulator is the destination register for 8-bit arith-

metic and logical operations. The six general-purpose

registers can be paired (BC, DE, and HL), and are ex-

tended to 32 bits by the extension to the register (with suffix

“z”; BCz/DEz/HLz), to form three 32-bit general-purpose

registers. The HL register serves as the 16-bit or 32-bit

accumulator for word operations. Access to the Extended

portion of the registers is possible using the SWAP instruc-

tion or word Load instructions in Long Word operation

mode.

The Flag register contains eight status flags. Four can be

individually used for control of program branching, two are

used to support decimal arithmetic, and two are reserved.

These flags are set or reset by various CPU operations. For

details on Flag operations, refer to Section 5.2, “Flag

Register.”

2.2.2. Index Registers

The four index registers, IX, IX’, IY, and IY’, are extended

to 32 bits by the extension to the register (with suffix “z”;

IXz/IYz), to form 32-bit index registers. To access the

Extended portion of the registers use the SWAP instruction

or word Load instructions in Long Word operation mode.

These Index registers hold a 32-bit base address that is

used in the Index addressing mode.

Only one register of each can be active at any given time,

although data in the inactive file can still be accessed by

using EX IX, IX’ and EX IY, IY’ (either in 16-bit or 32-bit wide

depending on the LW bit status). Index registers can also

function as general-purpose registers with the upper and

lower bytes of the lower 16 bits being accessed individu-

ally. These byte registers are called IXU, IXU’, IXL, and IXL’

for the IX and IX’ registers, and IYU, IYU’, IYL, and IYL’ for

the IY and IY’ registers.

Selection of primary or auxiliary Index registers can be

made by EXXX, EXXY, or EXALL instructions, or program-

ming of SR. Upon reset, the primary registers in register set

0 is active. Changing register sets is a simple matter of an

LDCTL instruction to program SR.

2.2.3. Interrupt Register

The Interrupt register (I) is used in interrupt modes 2 and

3 for /INT0 to generate a 32-bit indirect address to an

interrupt service routine. The I register supplies the upper

24 or 16 bits of the indirect address and the interrupting

peripheral supplies the lower eight or 16 bits. In Assigned

Vectors mode for /INT3-/INT1, the upper 16 bits of the

vector are supplied by the I register; bits 15-9 are supplied

from the Assigned Vector Base register, and bits 8-0 are

the assigned vector unique to each of /INT3-/INT1.

2.2.4. Program Counter

The Program Counter (PC) is used to sequence through

instructions in the currently executing program and to

generate relative addresses. The PC contains the 32-bit

address of the current instruction being fetched from

memory. In Native mode, the PC is effectively only 16 bits

long, since the upper word [PC31-PC16] of the PC is

forced to zero, and when carried from bit 15 to bit 16 (Lower

word [PC15-PC0] to Upper word [PC31-PC16]) are inhib-

ited in this mode. In Extended mode, the PC is allowed to

increment across all 32 bits.

2.2.5. R Register

The R register can be used as a general-purpose 8-bit

read/write register. The R register is not associated with

the refresh controller and its contents are changed only by

the user.

2.2.6. Stack Pointer

The Stack Pointer (SP) is used for saving information when

an interrupt or trap occurs and for supporting subroutine

calls and returns. Stack Pointer relative addressing allows

parameter passing using the SP. The SP is 16 bits wide, but

is extended by the SPz register to 32 bits wide.

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2.2.6 Stack Pointer (Continued)

Increment/decrement of the Stack Pointer is affected by

modes of operation (Native or Extended). In Native mode,

the stack operates in modulo 2

16

, and in Extended mode,

it operates in modulo 2

32

. For example, SP holds 0001FFFEH,

and does the Word size Pop operation. After the operation,

SP holds 00010000H in Native mode, and 00020000H in

Extended mode. In either case, SPz can be programmed

to set Stack frame. This is done by the Load- to-Stack

pointer instructions in Long Word mode.

2.3. CPU CONTROL REGISTER SPACE

The CPU control register space consists of the 32-bit

Select Register (SR). The SR may be accessed as a whole

or the upper three bytes of the SR may be accessed

individually as YSR, XSR, and DSR. In addition, these

upper three bytes can be loaded with the same byte value.

The SR may also be PUSHed and POPed and is cleared to

zeros on Reset. For details on this register, refer to Chapter

5.3, “Select Register.”

2.4 MEMORY ADDRESS SPACE

The memory address space can be viewed as a string of

4 Gbytes numbered consecutively in ascending order.

The 8-bit byte is the basic addressable element in the Z380

MPU memory address space. However, there are other

addressable data elements: bits, 2-byte words, byte strings,

and 4-byte words.

The size of the data element being addressed depends on

the instruction being executed as well as the Word/Long

Word mode. A bit can be addressed by specifying a byte

and a bit within that byte. Bits are numbered from right to

left, with the least significant bit being 0, as illustrated in

Figure 2-2.

The address of a multiple-byte entity is the same as the

address of the byte with the lowest memory address in the

entity. Multiple-byte entities can be stored beginning with

either even or odd memory addresses. A word (either 2-

byte or 4-byte entity) is aligned if its address is even;

otherwise it is unaligned. Multiple bus transactions, which

may be required to access multiple-byte entities, can be

minimized if alignment is maintained.

The format of multiple-byte data types is also shown in

Figure 2-2. Note that when a word is stored in memory, the

least significant byte precedes the more significant byte of

the word, as in the Z80 CPU architecture. Also, the lower-

addressed byte is present on the upper byte of the external

data bus.

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Bits within a byte:

16-bit word at address n:

Least Significant Byte

Most Significant Byte

Address n

Address n+1

32-bit word at address n:

D7-0 (Least Significant Byte)

D15-8

Address n

Address n+1

Address n+2

Address n+3

D31-24 (Most Significant Byte)

D23-16

Memory addresses:

Least Significant Byte

Even address (A0=0)

Most Significant Byte

Odd address (A0=1)

1514131211109876543210

Figure 2-2. Bit/Byte Ordering Conventions

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2.5. EXTERNAL I/O ADDRESS SPACE

External I/O address space is 4 Gbytes in size and External

I/O addresses are generated by I/O instructions except

those reserved for on-chip I/O address space accesses. It

can take a variety of forms, as shown in Table 2.1. An

external I/O read or write is always one transaction, regard-

less of the bus size and the type of I/O instruction.

Table 2-1. I/O Addressing Options

Address Bus

I/O Instruction A31-A24 A23-A16 A15-A8 A7-A0

IN A, (n) 00000000 00000000 A7-A0 n

IN dst,(C) BC31-B24 BC23-B16 BC15-B8 BC7-B0

INA(W) dst,(mn) 00000000 00000000 m n

DDIR IB INA(W) dst,(lmn) 00000000 l m n

DDIR IW INA(W) dst,(klmn) k l m n

Block Input BC31-B24 BC23-B16 BC15-B8 BC7-B0

OUT (n),A 00000000 00000000 A7-A0 n

OUT (C),dst BC31-B24 BC23-B16 BC15-B8 BC7-B0

OUTA(W) (mn),dst 00000000 00000000 m n

DDIR IB OUTA(W) (lmn),dst 00000000 l m n

DDIR IW OUTA(W) (klmn),dst k l m n

Block Output BC31-B24 BC23-B16 BC15-B8 BC7-B0

2.6. ON-CHIP I/O ADDRESS SPACE

The Z380 CPU has the on-chip I/O address space to

control on-chip peripheral functions of the Superintegra-

tion

™

version of the devices. A portion of its interrupt

functions are also controlled by several on-chip registers,

which occupy an on-chip I/O address space. This on-chip

I/O address space can be accessed only with the following

reserved on-chip I/O instructions which are identical to the

Z180 original I/O instructions to access Page 0 I/O ad-

dressing area.

IN0 R,(n) OTIM

IN0 (n) OTIMR

OUT0 (n),R OTDM

TSTIO n OTDMR

When one of these I/O instructions is executed, the Z380

MPU outputs the register address being accessed in a

pseudo-transaction of two BUSCLK cycles duration, with

the address signals A31-A8 at zero. In the pseudo-trans-

actions, all bus control signals are at their inactive state.

The following four registers are assigned to this address-

ing space as a part of the Z380 CPU core:

Register Name Internal I/O Address

Interrupt Enable Register 17H

Assigned Vector Base Register 18H

Trap and Break Register 19H

Chip Version ID Register 0FFH

The Chip Version ID register returns one byte data, which

indicates the version of the CPU, or the specific implemen-

tation of the Z380 CPU based Superintegration device.

Currently, the value 00H is assigned to the Z380 MPU, and

other values are reserved.

For the other three registers, refer to Chapter 6, “Interrupts

and Traps.”

Also, the Z380 MPU has registers to control chip selects,

refresh, waits, and I/O clock divide to Internal I/O address

00H to 10H. For these registers, refer to the Z380 MPU

Product specification (DC-3003-01).

2-7

Z380

™

USER'S MANUAL

ZILOG

DC-8297-03

Zilog’s products are not authorized for use as critical compo-

nents in life support devices or systems unless a specific written

agreement pertaining to such intended use is executed between

the customer and Zilog prior to use. Life support devices or

systems are those which are intended for surgical implantation

into the body, or which sustains life whose failure to perform,

when properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result in

significant injury to the user.

Zilog, Inc. 210 East Hacienda Ave.

Campbell, CA 95008-6600

Telephone [phone]

Telex 910-338-7621

FAX [phone]

Internet: http://www.zilog.com

© 1994, 1995, 1996, 1997 by Zilog, Inc. All rights reserved. No

part of this document may be copied or reproduced in any form

or by any means without the prior written consent of Zilog, Inc.

The information in this document is subject to change without

notice. Devices sold by Zilog, Inc. are covered by warranty and

patent indemnification provisions appearing in Zilog, Inc. Terms

and Conditions of Sale only.

ZILOG, INC. MAKES NO WARRANTY, EXPRESS, STATUTORY,

IMPLIED OR BY DESCRIPTION, REGARDING THE INFORMA-

TION SET FORTH HEREIN OR REGARDING THE FREEDOM OF

THE DESCRIBED DEVICES FROM INTELLECTUAL PROPERTY

INFRINGEMENT. ZILOG, INC. MAKES NO WARRANTY OF MER-

CHANTABILITY OR FITNESS FOR ANY PURPOSE.

Zilog, Inc. shall not be responsible for any errors that may appear

in this document. Zilog, Inc. makes no commitment to update or

keep current the information contained in this document.

2-1

Z380

™

USER'S MANUAL

ZILOG

DC-8297-03

2.1 INTRODUCTION

U

SER

’s M

ANUAL

CHAPTER 2

ADDRESS SPACES

The Z380 CPU supports five address spaces correspond-

ing to the different types of locations that can be ad-

dressed and the method by which the logical addresses

are formed. These five address spaces are:

■ CPU Register Space. This consists of all the register

addresses in the CPU register file.

■ CPU Control Register Space. This consists of the

Select Register (SR).

■ Memory Address Space. This consists of the

addresses of all locations in the main memory.

2.2 CPU REGISTER SPACE

The Z380 register file is illustrated in Figure 2-1. Note that

this figure shows the configuration of the register on the

Z380 CPU, and the number of the register files may vary on

future Superintegration devices. The Z380 CPU contains

abundant register resources. At any given time, the pro-

gram has immediate access to both primary and alternate

registers in the selected register set. Changing register

sets is a simple matter of an LDCTL instruction to program

the Select Register (SR).

The CPU register file is divided into five groups of registers

(an apostrophe indicates a register in the auxiliary regis-

ters).

■ Four sets of Flag and Accumulator registers (F, A, F’,

A’)

■ Four sets of Primary and Working registers (B, C, D, E,

H, L, B’, C’, D’, E’, H’, L’)

■ External I/O Address Space. This consists of all

external I/O ports addresses through which peripheral

devices are accessed.

■ On-Chip I/O Address Space. This consists of all

internal I/O port addresses through which peripheral

devices are accessed. Also, this addressing space

contains registers to control the functionality of the

device, giving status information.

■ Four sets of Index registers (IX, IY, IX’, IY’)

■ Stack Pointer (SP)

■ Program Counter, Interrupt register, Refresh register

(PC, I, R)

Register addresses are either specified explicitly in the

instruction or are implied by the semantics of the instruc-

tion.

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2.2 CPU REGISTER SPACE (Continued)

AF

BC

DE

HL

IXU IXL

IYU IYL

A' F'

B' C'

D' E'

H' L'

IXU' IXL'

IYU' IYL'

BCz'

DEz'

HLz'

IXz'

IYz'

BCz

DEz

HLz

IXz

IYz

R

I

SPz

PCz

Iz

SP

PC

4 Sets of Registers

Figure 2-1. Register File Organization (Z380 MPU)

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2.2.1 Primary and Working Registers

The working register set is divided into two register files:

the primary file and the alternate file (designated by prime

(‘)). Each file contains an 8-bit accumulator (A), a Flag

register (F), and six 8-bit general-purpose registers (B, C,

D, E, H, and L) with their Extended registers. Only one file

can be active at any given time, although data in the

inactive file can still be accessed by using EX R, R’

instructions for the byte-wide registers, EX RR, RR’ instruc-

tions for register pairs (either in 16-bit or 32-bit wide

depending on the LW status). Exchange instructions allow

the programmer to exchange the active file with the inac-

tive file. The EX AF, AF’, EXX, or EXALL instructions

changes the register files in use. Upon reset, the primary

register file in register set 0 is active. Changing register

sets is a simple matter of an LDCTL instruction to program

SR.

The accumulator is the destination register for 8-bit arith-

metic and logical operations. The six general-purpose

registers can be paired (BC, DE, and HL), and are ex-

tended to 32 bits by the extension to the register (with suffix

“z”; BCz/DEz/HLz), to form three 32-bit general-purpose

registers. The HL register serves as the 16-bit or 32-bit

accumulator for word operations. Access to the Extended

portion of the registers is possible using the SWAP instruc-

tion or word Load instructions in Long Word operation

mode.

The Flag register contains eight status flags. Four can be

individually used for control of program branching, two are

used to support decimal arithmetic, and two are reserved.

These flags are set or reset by various CPU operations. For

details on Flag operations, refer to Section 5.2, “Flag

Register.”

2.2.2. Index Registers

The four index registers, IX, IX’, IY, and IY’, are extended

to 32 bits by the extension to the register (with suffix “z”;

IXz/IYz), to form 32-bit index registers. To access the

Extended portion of the registers use the SWAP instruction

or word Load instructions in Long Word operation mode.

These Index registers hold a 32-bit base address that is

used in the Index addressing mode.

Only one register of each can be active at any given time,

although data in the inactive file can still be accessed by

using EX IX, IX’ and EX IY, IY’ (either in 16-bit or 32-bit wide

depending on the LW bit status). Index registers can also

function as general-purpose registers with the upper and

lower bytes of the lower 16 bits being accessed individu-

ally. These byte registers are called IXU, IXU’, IXL, and IXL’

for the IX and IX’ registers, and IYU, IYU’, IYL, and IYL’ for

the IY and IY’ registers.

Selection of primary or auxiliary Index registers can be

made by EXXX, EXXY, or EXALL instructions, or program-

ming of SR. Upon reset, the primary registers in register set

0 is active. Changing register sets is a simple matter of an

LDCTL instruction to program SR.

2.2.3. Interrupt Register

The Interrupt register (I) is used in interrupt modes 2 and

3 for /INT0 to generate a 32-bit indirect address to an

interrupt service routine. The I register supplies the upper

24 or 16 bits of the indirect address and the interrupting

peripheral supplies the lower eight or 16 bits. In Assigned

Vectors mode for /INT3-/INT1, the upper 16 bits of the

vector are supplied by the I register; bits 15-9 are supplied

from the Assigned Vector Base register, and bits 8-0 are

the assigned vector unique to each of /INT3-/INT1.

2.2.4. Program Counter

The Program Counter (PC) is used to sequence through

instructions in the currently executing program and to

generate relative addresses. The PC contains the 32-bit

address of the current instruction being fetched from

memory. In Native mode, the PC is effectively only 16 bits

long, since the upper word [PC31-PC16] of the PC is

forced to zero, and when carried from bit 15 to bit 16 (Lower

word [PC15-PC0] to Upper word [PC31-PC16]) are inhib-

ited in this mode. In Extended mode, the PC is allowed to

increment across all 32 bits.

2.2.5. R Register

The R register can be used as a general-purpose 8-bit

read/write register. The R register is not associated with

the refresh controller and its contents are changed only by

the user.

2.2.6. Stack Pointer

The Stack Pointer (SP) is used for saving information when

an interrupt or trap occurs and for supporting subroutine

calls and returns. Stack Pointer relative addressing allows

parameter passing using the SP. The SP is 16 bits wide, but

is extended by the SPz register to 32 bits wide.

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2.2.6 Stack Pointer (Continued)

Increment/decrement of the Stack Pointer is affected by

modes of operation (Native or Extended). In Native mode,

the stack operates in modulo 2

16

, and in Extended mode,

it operates in modulo 2

32

. For example, SP holds 0001FFFEH,

and does the Word size Pop operation. After the operation,

SP holds 00010000H in Native mode, and 00020000H in

Extended mode. In either case, SPz can be programmed

to set Stack frame. This is done by the Load- to-Stack

pointer instructions in Long Word mode.

2.3. CPU CONTROL REGISTER SPACE

The CPU control register space consists of the 32-bit

Select Register (SR). The SR may be accessed as a whole

or the upper three bytes of the SR may be accessed

individually as YSR, XSR, and DSR. In addition, these

upper three bytes can be loaded with the same byte value.

The SR may also be PUSHed and POPed and is cleared to

zeros on Reset. For details on this register, refer to Chapter

5.3, “Select Register.”

2.4 MEMORY ADDRESS SPACE

The memory address space can be viewed as a string of

4 Gbytes numbered consecutively in ascending order.

The 8-bit byte is the basic addressable element in the Z380

MPU memory address space. However, there are other

addressable data elements: bits, 2-byte words, byte strings,

and 4-byte words.

The size of the data element being addressed depends on

the instruction being executed as well as the Word/Long

Word mode. A bit can be addressed by specifying a byte

and a bit within that byte. Bits are numbered from right to

left, with the least significant bit being 0, as illustrated in

Figure 2-2.

The address of a multiple-byte entity is the same as the

address of the byte with the lowest memory address in the

entity. Multiple-byte entities can be stored beginning with

either even or odd memory addresses. A word (either 2-

byte or 4-byte entity) is aligned if its address is even;

otherwise it is unaligned. Multiple bus transactions, which

may be required to access multiple-byte entities, can be

minimized if alignment is maintained.

The format of multiple-byte data types is also shown in

Figure 2-2. Note that when a word is stored in memory, the

least significant byte precedes the more significant byte of

the word, as in the Z80 CPU architecture. Also, the lower-

addressed byte is present on the upper byte of the external

data bus.

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Bits within a byte:

16-bit word at address n:

Least Significant Byte

Most Significant Byte

Address n

Address n+1

32-bit word at address n:

D7-0 (Least Significant Byte)

D15-8

Address n

Address n+1

Address n+2

Address n+3

D31-24 (Most Significant Byte)

D23-16

Memory addresses:

Least Significant Byte

Even address (A0=0)

Most Significant Byte

Odd address (A0=1)

1514131211109876543210

Figure 2-2. Bit/Byte Ordering Conventions

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2.5. EXTERNAL I/O ADDRESS SPACE

External I/O address space is 4 Gbytes in size and External

I/O addresses are generated by I/O instructions except

those reserved for on-chip I/O address space accesses. It

can take a variety of forms, as shown in Table 2.1. An

external I/O read or write is always one transaction, regard-

less of the bus size and the type of I/O instruction.

Table 2-1. I/O Addressing Options

Address Bus

I/O Instruction A31-A24 A23-A16 A15-A8 A7-A0

IN A, (n) 00000000 00000000 A7-A0 n

IN dst,(C) BC31-B24 BC23-B16 BC15-B8 BC7-B0

INA(W) dst,(mn) 00000000 00000000 m n

DDIR IB INA(W) dst,(lmn) 00000000 l m n

DDIR IW INA(W) dst,(klmn) k l m n

Block Input BC31-B24 BC23-B16 BC15-B8 BC7-B0

OUT (n),A 00000000 00000000 A7-A0 n

OUT (C),dst BC31-B24 BC23-B16 BC15-B8 BC7-B0

OUTA(W) (mn),dst 00000000 00000000 m n

DDIR IB OUTA(W) (lmn),dst 00000000 l m n

DDIR IW OUTA(W) (klmn),dst k l m n

Block Output BC31-B24 BC23-B16 BC15-B8 BC7-B0

2.6. ON-CHIP I/O ADDRESS SPACE

The Z380 CPU has the on-chip I/O address space to

control on-chip peripheral functions of the Superintegra-

tion

™

version of the devices. A portion of its interrupt

functions are also controlled by several on-chip registers,

which occupy an on-chip I/O address space. This on-chip

I/O address space can be accessed only with the following

reserved on-chip I/O instructions which are identical to the

Z180 original I/O instructions to access Page 0 I/O ad-

dressing area.

IN0 R,(n) OTIM

IN0 (n) OTIMR

OUT0 (n),R OTDM

TSTIO n OTDMR

When one of these I/O instructions is executed, the Z380

MPU outputs the register address being accessed in a

pseudo-transaction of two BUSCLK cycles duration, with

the address signals A31-A8 at zero. In the pseudo-trans-

actions, all bus control signals are at their inactive state.

The following four registers are assigned to this address-

ing space as a part of the Z380 CPU core:

Register Name Internal I/O Address

Interrupt Enable Register 17H

Assigned Vector Base Register 18H

Trap and Break Register 19H

Chip Version ID Register 0FFH

The Chip Version ID register returns one byte data, which

indicates the version of the CPU, or the specific implemen-

tation of the Z380 CPU based Superintegration device.

Currently, the value 00H is assigned to the Z380 MPU, and

other values are reserved.

For the other three registers, refer to Chapter 6, “Interrupts

and Traps.”

Also, the Z380 MPU has registers to control chip selects,

refresh, waits, and I/O clock divide to Internal I/O address

00H to 10H. For these registers, refer to the Z380 MPU

Product specification (DC-3003-01).

2-7

Z380

™

USER'S MANUAL

ZILOG

DC-8297-03

Zilog’s products are not authorized for use as critical compo-

nents in life support devices or systems unless a specific written

agreement pertaining to such intended use is executed between

the customer and Zilog prior to use. Life support devices or

systems are those which are intended for surgical implantation

into the body, or which sustains life whose failure to perform,

when properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result in

significant injury to the user.

Zilog, Inc. 210 East Hacienda Ave.

Campbell, CA 95008-6600

Telephone [phone]

Telex 910-338-7621

FAX [phone]

Internet: http://www.zilog.com

© 1994, 1995, 1996, 1997 by Zilog, Inc. All rights reserved. No

part of this document may be copied or reproduced in any form

or by any means without the prior written consent of Zilog, Inc.

The information in this document is subject to change without

notice. Devices sold by Zilog, Inc. are covered by warranty and

patent indemnification provisions appearing in Zilog, Inc. Terms

and Conditions of Sale only.

ZILOG, INC. MAKES NO WARRANTY, EXPRESS, STATUTORY,

IMPLIED OR BY DESCRIPTION, REGARDING THE INFORMA-

TION SET FORTH HEREIN OR REGARDING THE FREEDOM OF

THE DESCRIBED DEVICES FROM INTELLECTUAL PROPERTY

INFRINGEMENT. ZILOG, INC. MAKES NO WARRANTY OF MER-

CHANTABILITY OR FITNESS FOR ANY PURPOSE.

Zilog, Inc. shall not be responsible for any errors that may appear

in this document. Zilog, Inc. makes no commitment to update or

keep current the information contained in this document.

3-1

Z380

™

USER'S MANUAL

ZILOG

DC-8297-03

3.1 INTRODUCTION

U

SER

’s M

ANUAL

CHAPTER 3

NATIVE EXTENDED MODE, WORD/LONG

WORD MODE OF OPERATIONS

AND

DECODER DIRECTIONS

The Z380

™

CPU architecture allows access to 4 Gbytes

(2

32

) of memory addressing space, and 4G locations of

I/O. It offers 16/32-bit manipulation capability while main-

taining object-code compatibility with the Z80 CPU. In

order to implement these capabilities and new instruction

sets, it has two modes of operation for address manipula-

tion (Native or Extended mode), two modes of operation for

data manipulation (Word or Long Word mode), and a

special set of new Decoder Directives.

On Reset, the Z380 CPU defaults in Native mode and Word

mode. In this condition, it behaves exactly the same as the

Z80 CPU, even though it has access to the entire 4 Gbytes

of memory for data access and 4G locations of I/O space,

access to the newly added registers which includes Ex-

tended registers and register banks, and the capability of

executing all the Z380 instructions.

As described below, the Z380 CPU can be switched

between Word mode and Long Word mode during opera-

tion through the SETC LW and RESC LW instructions, or

Decoder Directives. The Native and Extended modes are

a key exception— it defaults up in Native mode, and can

be set to Extended mode by the instruction. Only Reset can

return it to Native mode. Figure 3-1 illustrates the relation-

ship between these modes of operation.

For the instructions which work with the DDIR instructions, refer to Appendix D and E.

Word

Long Word

Native

Z380

Extended

Z80 Native Mode

Figure 3-1. Z380

™

CPU Operation Modes

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3.2 DECODER DIRECTIVES

The Decoder Directive is not an instruction, but rather a

directive to the instruction decoder. The instruction de-

coder may be directed to fetch an additional byte or word

of immediate data or address with the instruction, as well

as tagging the instruction for execution in either Word or

Long Word mode. Since the Z80 CPU architecture’s ad-

dressing convention in the memory is “least significant

byte first, followed by more significant bytes,” it is possible

to have such instructions to direct the instruction decoder

to fetch additional byte(s) of address information or imme-

diate data to extend the instruction.

All eight combinations of the two options are supported, as

shown below. Instructions which do not support decoder

directives are assembled by the instruction decoder as if

the decoder directive were not present.

■ DDIR W Word mode

■ DDIR IB,W Immediate byte, Word mode

■ DDIR IW,W Immediate Word, Word mode

■ DDIR IB Immediate byte

■ DDIR LW Long Word mode

■ DDIR IB,LW Immediate byte, Long Word mode

■ DDIR IW,LW Immediate Word, Long Word

mode

■ DDIR IW Immediate Word

The IB decoder directive causes the decoder to fetch an

additional byte immediately after the existing immediate

data or direct address, and in front of any trailing opcode

bytes (with instructions starting with DD-CB or FD-CB, for

example).

Likewise, the IW decoder directive causes the decoder to

fetch an additional word immediately after the existing

immediate data or direct address, and in front of any

trailing opcode bytes.

Byte ordering within the instruction follows the usual con-

vention; least significant byte first, followed by more signifi-

cant bytes. More-significant immediate data or direct

address bytes not specified in the instruction are read as

all zeros by the processor.

The W decoder directive causes the instruction decoder to

tag the instruction for execution in Word mode. This is

useful while the Long Word (LW) bit in the Select Register

(SR) is set, but 16-bit data manipulation is required for this

instruction.

The LW decoder directive causes the instruction decoder

to tag the instruction for execution in Long Word mode.

This is useful while the LW bit in the SR is cleared, but 32-

bit data manipulation is required for this instruction.

3.3 NATIVE MODE AND EXTENDED MODE

The Z380 CPU can operate in either Native or Extended

mode, as a way to manipulate addresses.

In Native mode (the Reset configuration), the Program

Counter only increments across 16 bits, and all stack Push

and Pop operations manipulate 16-bit quantities (two

bytes). Thus, Native mode is fully compatible with the Z80

CPU’s 64 Kbyte address space and programming model.

The extended portion of the Program Counter (PC31-

PC15) is forced to 0 and program address location next to

0000FFFFH is 00000000H in this mode. This means in

Native mode, program have to reside within the first 64

Kbytes of the memory addressing space.

In Extended mode, however, the PC increments across all

32 bits and all stack Push and Pop operations manipulate

32-bit quantities. Thus, Extended mode allows access to

the entire 4 Gbyte address space. In both Native and

Extended modes, the Z380 CPU drives all 32 bits of the

address onto the external address bus; only the PC incre-

ments and stack operations distinguish Native from Ex-

tended mode.

Note that regardless of Native or Extended mode, a 32-bit

address is always used for the data access. Thus, for data

reference, the complete 4 Gbytes of memory area may be

accessed. For example:

LD BC, (HL)

uses the 32-bit address value stored in HL31-HL0 (HLz

and HL) as a source location address. However, on Reset,

the HL31-HL16 portion (HLz) initializes to 00H. Unless HLz

is modified to other than 00H, operation of this instruction

is identical to the one with the Z80 CPU. Modifying the

extended portion of the register is done either by using a

32-bit load instruction (in Long Word mode, or with DDIR

LW instructions), or using a 16-bit load instruction with

SWAP instructions.

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The Z380 CPU implements one instruction to switch to

Extended mode from Native mode; SETC XM (set Ex-

tended mode) places the Z380 CPU in Extended mode.

Once in Extended mode, only Reset can return it to Native

mode. On Reset, the Z380 is in Native mode. Refer to

Sections 4 and 5 for more examples.

3.4 WORD AND LONG WORD MODE OF OPERATION

The Z380 CPU can operate in either Word or Long Word

mode. In Word mode (the Reset configuration), all word

operations manipulate 16-bit quantities, and are compat-

ible with the Z80 CPU 16-bit operations. In the Long Word

mode, all word operations can manipulate 32-bit quanti-

ties. Note that the Native/Extended and Word/Long Word

selections are independent of one another, as Word/Long

Word pertains to data and operand address manipulation

only. The Z380 CPU implements two instructions and two

decoder directives to allow switching between these two

modes; SETC LW (Set Long Word) and RESC LW (Reset

Long Word) perform a global switch, while DDIR LW and

DDIR W are decoder directives that select a particular

mode only for the instruction that they precede.

Examples:

1. Effect of Word mode and Long Word mode

DDIR W

LD BC, (HL)

Loads BC15-BC0 from the location (HL) and

(HL+1), and BCz (BC31-BC16) remains un-

changed.

DDIR LW

LD BC, (HL)

Loads BC31-BC0 from the locations (HL) to (HL+3).

2. Immediate data load with DDIR instructions

DDIR IW,LW

LD HL,12345678H

Loads 12345678H into HL31-HL0.

DDIR IB,LW

LD HL,123456H

Loads 00123456H into HL31-HL0.

00H is appended as the Most significant byte as

HL31-HL24.

DDIR LW

LD HL,1234H

Loads 00001234H into HL31-HL0.

0000H is appended as the HL31-HL16 portion.

Zilog’s products are not authorized for use as critical compo-

nents in life support devices or systems unless a specific written

agreement pertaining to such intended use is executed between

the customer and Zilog prior to use. Life support devices or

systems are those which are intended for surgical implantation

into the body, or which sustains life whose failure to perform,

when properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result in

significant injury to the user.

Zilog, Inc. 210 East Hacienda Ave.

Campbell, CA 95008-6600

Telephone [phone]

Telex 910-338-7621

FAX [phone]

Internet: http://www.zilog.com

© 1994, 1995, 1996, 1997 by Zilog, Inc. All rights reserved. No

part of this document may be copied or reproduced in any form

or by any means without the prior written consent of Zilog, Inc.

The information in this document is subject to change without

notice. Devices sold by Zilog, Inc. are covered by warranty and

patent indemnification provisions appearing in Zilog, Inc. Terms

and Conditions of Sale only.

ZILOG, INC. MAKES NO WARRANTY, EXPRESS, STATUTORY,

IMPLIED OR BY DESCRIPTION, REGARDING THE INFORMA-

TION SET FORTH HEREIN OR REGARDING THE FREEDOM OF

THE DESCRIBED DEVICES FROM INTELLECTUAL PROPERTY

INFRINGEMENT. ZILOG, INC. MAKES NO WARRANTY OF MER-

CHANTABILITY OR FITNESS FOR ANY PURPOSE.

Zilog, Inc. shall not be responsible for any errors that may appear

in this document. Zilog, Inc. makes no commitment to update or

keep current the information contained in this document.

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4.1 INSTRUCTION

U

SER

’s M

ANUAL

CHAPTER 4

ADDRESSING MODES AND DATA TYPES

An instruction is a consecutive list of one or more bytes in

memory. Most instructions act upon some data; the term

operand refers to the data to be operated upon. For Z380

™

CPU instructions, operands can reside in CPU registers,

memory locations, or I/O ports (internal or external). The

method used to designate the location of the operands for

an instruction are called addressing modes. The Z380

CPU supports seven addressing modes; Register, Imme-

diate, Indirect Register, Direct Address, Indexed, Program

Counter Relative Address, and Stack Pointer Relative. A

wide variety of data types can be accessed using these

addressing modes.

4.2 ADDRESSING MODE DESCRIPTIONS

The following pages contain descriptions of the address-

ing modes for the Z380 CPU. Each description explains

how the operand’s location is calculated, indicates which

address spaces can be accessed with that particular

addressing mode, and gives an example of an instruction

using that mode, illustrating the assembly language format

for the addressing modes.

4.2.1 Register (R, RX)

When this addressing mode is used, the instruction pro-

cesses data taken from one of the 8-bit registers A, B, C,

D, E, H, L, IXU, IXL, IYU, IYL, one of the 16-bit registers BC,

DE, HL, IX, IY, SP, or one of the special byte registers I or

R.

Storing data in a register allows shorter instructions and

faster execution that occur with instructions that access

memory.

Instruction

OPERATION REGISTER → OPERAND

The operand value is the contents of the register.

The operand is always in the register address space. The

register length (byte or word) is specified by the instruction

opcode. In the case of Long Word register operation, it is

specified either through the SETC LW instruction or the

DDIR LW decoder directive.

Example of R mode:

1. Load register in Word mode.

DDIR W ;Next instruction in Word mode

LD BC,HL ;Load the contents of HL into BC

BCz BC HLz HL

Before instruction

execution 1234 5678 9ABC DEF0

After instruction

execution 1234 DEF0 9ABC DEF0

2. Load register in Long Word mode.

DDIR LW ;Next instruction in Long Word mode

LD BC,HL ;Load the contents of HL into BC

BCz BC HLz HL

Before instruction

execution 1234 5678 9ABC DEF0

After instruction

execution 9ABC DEF0 9ABC DEF0

4.2.2 Immediate (IM)

When the Immediate addressing mode is used, the data

processed is in the instruction.

The Immediate addressing mode is the only mode that

does not indicate a register or memory address as the

source operand.

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4.2.2 Immediate (IM) (Continued)

Instruction

OPERATION

OPERAND

The operand value is in the instruction

Immediate mode is often used to initialize registers. Also,

this addressing mode is affected by the DDIR Immediate

Data Directives to expand the immediate value to 24 bits

or 32 bits.

Example of IM mode:

1. Load immediate value into accumulator

LD A,55H ;Load hex 55 into the accumulator.

A

Before instruction execution 12

After instruction execution 55

4.2.3 Indirect Register (IR)

In Indirect Register addressing mode, the register speci-

fied in the instruction holds the address of the operand.

The data to be processed is in the location specified by the

BC, DE, or HL register (depending on the instruction) for

memory accesses, or C register for I/O.

Memory or

Instruction Register I/O Port

OPERATION REGISTER → Address → OPERAND

The operand value is the contents of the location whose address is in the register.

Depending on the instruction, the operand specified by IR

mode is located in either the I/O address space (I/O

instruction) or memory address space (all other instruc-

tions).

Indirect Register mode can save space and reduce ex-

ecution time when consecutive locations are referenced or

one location is repeatedly accessed. This mode can also

be used to simulate more complex addressing modes,

since addresses can be computed before data is ac-

cessed.

The address in this mode is always treated as a 32-bit

mode. After reset, the contents of the extend registers

(registers with “z” suffix) are initialized as 0's; hence, these

instructions will be executed just as for the Z80/Z180.

Example of IR mode:

1. Load accumulator from the contents of memory

pointed by (HL)

LD A, (HL) ;Load the accumulator with the data

;addressed by the contents of HL

A HLz,HL

Before instruction

execution 0F 12345678

After instruction

execution 0B 12345678

Memory location 12345678 0B

2. Load 24-bit immediate value into HL

register

DDIR IB, LW ;next instruction is in Long Word

mode, with ;an additional

immediate data

LD HL, 123456H ;load HLz, and HL with constant

123456H

This case, the Z380 CPU appends 00H as a MSB byte.

HLz HL

Before instruction execution 0987 6543

After instruction execution 0012 3456

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4.2.4 Direct Address (DA)

When Direct Address mode is used, the data processed is

at the location whose memory or I/O port address is in the

instruction.

Instruction Memory or

OPERATION I/O Port

ADDRESS → OPERAND

The operand value is the contents of the location whose

address is in the instruction.

Depending on the instruction, the operand specified by

DA mode is either in the I/O address space (I/O instruction)

or memory address space (all other instructions).

This mode is also used by Jump and Call instructions to

specify the address of the next instruction to be executed.

(The address serves as an immediate value that is loaded

into the program counter.)

Also, DDIR Immediate Data Directives are used to expand

the direct address to 24 or 32 bits. Operand width is

affected by LW bit status for the load and exchange

instructions.

Example of DA mode:

1. Load BC register from memory location 00005E22H in Word mode

LD BC, (5E22H) ;Load BC with the data in address

;00005E22H

BC

Before instruction execution 1234

After instruction execution 0301

Memory location 00005E22 01

00005E23 03

2. Load BC register from memory location 12345E22H in Word mode

DDIR IW ;extend direct address by one word

LD BC, (12345E22H) ;Load BC with the data in address

;12345E22H

BC

Before instruction execution 1234

After instruction execution 0301

Memory location 12345E22 01

12345E23 03

3. Load BC register from memory location 12345E22H in Long Word mode

DDIR IW,LW ;extend direct address by one word,

;and operation in Long Word

LD BC, (12345E22H) ;Load BC with the data in address

;12345E22H

BCz BC

Before instruction execution 1234 5678

After instruction execution 0705 0301

Memory location 12345E22 01

12345E23 03

12345E24 05

12345E25 07

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4.2.5 Indexed (X)

When the Indexed addressing mode is used, the data

processed is at the location whose address is the contents

of IX or IY in use, offset by an 8-bit signed displacement in

the instruction.

The Indexed address is computed by adding the 8-bit

two’s complement signed displacement specified in the

instruction to the contents of the IX or IY register in use, also

specified by the instruction. Indexed addressing allows

random access to tables or other complex data structures

where the address of the base of the table is known, but the

particular element index must be computed by the pro-

gram.

The offset portion can be expanded to 16 or 24 bits,

instead of eight bits by using DDIR Immediate Data Direc-

tives (DDIR IB for 16-bit offset, DDIR IW for 24-bit offset).

Note that computation of the effective address is affected

by the operation mode (Native or Extended). In Native

mode, address computation is done in modulo 2

16

, and in

Extended mode, address computation is done in modulo

2

32

.

Address calculation: In Native mode, 0FFH encoding in

the instruction is sign extended to a 16-bit value before the

address calculation, but calculation is done in modulo 2

16

and does not take into account the index register’s

extended portion.

0000

+ FFFF

FFFF

Instruction REGISTER MEMORY

OPERATION REGISTER → ADDRESS →+ OPERAND

DISPLACEMENT _____________________________________ ↑

Example of X mode:

1. Load accumulator from location (IX-1) in Native mode

LD A, (IX-1) ;Load into the accumulator the

;contents of the memory location

;whose address is one less than

;the contents of IX

;Assume it is in Native mode

A IXz IX

Before instruction execution 01 0001 0000

After instruction execution 23 0001 0000

Memory location 0001FFFF 23

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2. Load accumulator from location (IX-1) in Extended mode

SETC XM ;Set Extended mode

LD A, (IX-1) ;Load into the accumulator the

;contents of the memory location

;whose address is one less than

;the contents of IX

A IXz IX

Before instruction execution 01 0001 0000

After instruction execution 23 0001 0000

Memory location 0000FFFF 23

Address calculation: In Extended mode, 0FFH encoding in

the instruction is sign extended to a 32-bit value before the

address calculation, but calculation is done in modulo 2

32

and takes into account the index register’s extended

portion.

00010000

+ FFFFFFFF

0000FFFF

4.2.6 Program Counter Relative Mode (RA)

The Program Counter Relative Addressing mode is used

by certain program control instructions to specify the

address of the next instruction to be executed (specifically,

the sum of the Program Counter value and the displace-

ment value is loaded into the Program Counter). Relative

addressing allows reference forward or backward from the

current Program Counter value; it is used for program

control instructions such as Jumps and Calls that access

constants in the memory.

As a displacement, an 8-bit, 16-bit, or 24-bit value can be

used. The address to be loaded into the Program Counter

is computed by adding the two’s complement signed

displacement specified in the instruction to the current

Program Counter.

Note that computation of the effective address is affected

by the mode of operation (Native or Extended). In Native

mode, address computation is done in modulo 2

16

, and the

PC Extend (PC31-PC16) is forced to 0 and will not affect

this portion. In Extended mode, address computation is

done is modulo 2

32

, and will affect the contents of PC

extend if there is a carry or borrow operation.

Also, in Native mode,

Instruction PC MEMORY

OPERATION ADDRESS →+ OPERAND

DISPLACEMENT —↑

Example of RA mode:

1. Jump relative in Native mode, 8-bit displacement

JR $-2 ;Jumps to the location

;(Current PC value) – 2

;’$’ represents for current PC value

;This instruction jumps to itself.

;since after the execution of this instruction,

;PC points to the next instruction.