NEC 78K-0 User Manual

User’s Manual

78K/0 Series

Instructions

Common to 78K/0 Series

Document No. U12326EJ4V0UM00 (4th edition) Date Published October 2001 N CP(K)

Printed in Japan

1995

[MEMO]

User's Manual U12326EJ4V0UM

NOTES FOR CMOS DEVICES

1 PRECAUTION AGAINST ESD FOR SEMICONDUCTORS

Note:

Strong electric field, when exposed to a MOS device, can cause destruction of the gate oxide and

ultimately degrade the device operation. Steps must be taken to stop generation of static electricity

as much as possible, and quickly dissipate it once, when it has occurred. Environmental control

must be adequate. When it is dry, humidifier should be used. It is recommended to avoid using

insulators that easily build static electricity. Semiconductor devices must be stored and transported

in an anti-static container, static shielding bag or conductive material. All test and measurement

tools including work bench and floor should be grounded. The operator should be grounded using

wrist strap. Semiconductor devices must not be touched with bare hands. Similar precautions need

to be taken for PW boards with semiconductor devices on it.

2 HANDLING OF UNUSED INPUT PINS FOR CMOS

Note:

No connection for CMOS device inputs can be cause of malfunction. If no connection is provided

to the input pins, it is possible that an internal input level may be generated due to noise, etc., hence

causing malfunction. CMOS devices behave differently than Bipolar or NMOS devices. Input levels

of CMOS devices must be fixed high or low by using a pull-up or pull-down circuitry. Each unused

pin should be connected to V

or GND with a resistor, if it is considered to have a possibility of

being an output pin. All handling related to the unused pins must be judged device by device and

related specifications governing the devices.

3 STATUS BEFORE INITIALIZATION OF MOS DEVICES

Note:

Power-on does not necessarily define initial status of MOS device. Production process of MOS

does not define the initial operation status of the device. Immediately after the power source is

turned ON, the devices with reset function have not yet been initialized. Hence, power-on does

not guarantee out-pin levels, I/O settings or contents of registers. Device is not initialized until the

reset signal is received. Reset operation must be executed immediately after power-on for devices

having reset function.

Caution: Purchase of NEC I2C components conveys a license under the Philips I2C Patent Rights to use these

components in an I

defined by Philips.

IEBus is a trademark of NEC Corporation.

C system, provided that the system conforms to the I2C Standard Specification as

User's Manual U12326EJ4V0UM

The export of these products from Japan is regulated by the Japanese government. The export of some or all of these products may be prohibited without governmental license. To export or re-export some or all of these products from a country other than Japan may also be prohibited without a license from that country. Please call an NEC sales representative.

•

The information in this document is current as of August, 2001. The information is subject to change without notice. For actual design-in, refer to the latest publications of NEC's data sheets or data books, etc., for the most up-to-date specifications of NEC semiconductor products. Not all products and/or types are available in every country. Please check with an NEC sales representative for availability and additional information.

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No part of this document may be copied or reproduced in any form or by any means without prior written consent of NEC. NEC assumes no responsibility for any errors that may appear in this document.

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NEC does not assume any liability for infringement of patents, copyrights or other intellectual property rights of third parties by or arising from the use of NEC semiconductor products listed in this document or any other liability arising from the use of such products. No license, express, implied or otherwise, is granted under any patents, copyrights or other intellectual property rights of NEC or others.

•

Descriptions of circuits, software and other related information in this document are provided for illustrative purposes in semiconductor product operation and application examples. The incorporation of these circuits, software and information in the design of customer's equipment shall be done under the full responsibility of customer. NEC assumes no responsibility for any losses incurred by customers or third parties arising from the use of these circuits, software and information.

•

While NEC endeavours to enhance the quality, reliability and safety of NEC semiconductor products, customers agree and acknowledge that the possibility of defects thereof cannot be eliminated entirely. To minimize risks of damage to property or injury (including death) to persons arising from defects in NEC semiconductor products, customers must incorporate sufficient safety measures in their design, such as redundancy, fire-containment, and anti-failure features.

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NEC semiconductor products are classified into the following three quality grades: "Standard", "Special" and "Specific". The "Specific" quality grade applies only to semiconductor products developed based on a customer-designated "quality assurance program" for a specific application. The recommended applications of a semiconductor product depend on its quality grade, as indicated below. Customers must check the quality grade of each semiconductor product before using it in a particular application. "Standard": Computers, office equipment, communications equipment, test and measurement equipment, audio

and visual equipment, home electronic appliances, machine tools, personal electronic equipment and industrial robots

"Special": Transportation equipment (automobiles, trains, ships, etc.), traffic control systems, anti-disaster

systems, anti-crime systems, safety equipment and medical equipment (not specifically designed for life support)

"Specific": Aircraft, aerospace equipment, submersible repeaters, nuclear reactor control systems, life

support systems and medical equipment for life support, etc. The quality grade of NEC semiconductor products is "Standard" unless otherwise expressly specified in NEC's data sheets or data books, etc. If customers wish to use NEC semiconductor products in applications not intended by NEC, they must contact an NEC sales representative in advance to determine NEC's willingness to support a given application. (Note) (1) "NEC" as used in this statement means NEC Corporation and also includes its majority-owned subsidiaries. (2) "NEC semiconductor products" means any semiconductor product developed or manufactured by or for

NEC (as defined above).

M8E 00. 4

User's Manual U12326EJ4V0UM

Regional Information

Some information contained in this document may vary from country to country. Before using any NEC product in your application, pIease contact the NEC office in your country to obtain a list of authorized representatives and distributors. They will verify:

•

Device availability

•

Ordering information

•

Product release schedule

•

Availability of related technical literature

•

Development environment specifications (for example, specifications for third-party tools and

components, host computers, power plugs, AC supply voltages, and so forth)

•

Network requirements

In addition, trademarks, registered trademarks, export restrictions, and other legal issues may also vary from country to country.

NEC Electronics Inc. (U.S.)

Santa Clara, California Tel: 408-588-6000 800-366-9782 Fax: 408-588-6130 800-729-9288

NEC Electronics (Germany) GmbH

Duesseldorf, Germany Tel: 0211-65 03 02 Fax: 0211-65 03 490

NEC Electronics (UK) Ltd.

Milton Keynes, UK Tel: 01908-691-133 Fax: 01908-670-290

NEC Electronics Italiana s.r.l.

Milano, Italy Tel: 02-66 75 41 Fax: 02-66 75 42 99

NEC Electronics (Germany) GmbH

Benelux Office Eindhoven, The Netherlands Tel: 040-2445845 Fax: 040-2444580

NEC Electronics (France) S.A.

Velizy-Villacoublay, France Tel: 01-3067-5800 Fax: 01-3067-5899

NEC Electronics (France) S.A.

Madrid Office Madrid, Spain Tel: 091-504-2787 Fax: 091-504-2860

NEC Electronics (Germany) GmbH

Scandinavia Office Taeby, Sweden Tel: 08-63 80 820 Fax: 08-63 80 388

NEC Electronics Hong Kong Ltd.

Hong Kong Tel: 2886-9318 Fax: 2886-9022/9044

NEC Electronics Hong Kong Ltd.

Seoul Branch Seoul, Korea Tel: 02-528-0303 Fax: 02-528-4411

NEC Electronics Singapore Pte. Ltd.

Novena Square, Singapore Tel: 253-8311 Fax: 250-3583

NEC Electronics Taiwan Ltd.

Taipei, Taiwan Tel: 02-2719-2377 Fax: 02-2719-5951

NEC do Brasil S.A.

Electron Devices Division Guarulhos-SP, Brasil Tel: 11-6462-6810 Fax: 11-6462-6829

User's Manual U12326EJ4V0UM

J01.2

Major Revisions in This Edition

Page Description

Throughout Deletion of all information except for information common to

the 78K/0 Series (for individual product information, refer to the

user’s manual of each product).

The mark shows major revised points.

User's Manual U12326EJ4V0UM

INTRODUCTION

Target Readers This manual is intended for users who wish to understand the functions of

78K/0 Series products and to design and develop its application systems and

programs.

Purpose This manual is intended to give users an understanding of the various kinds of

instruction functions of 78K/0 Series products.

Organization This manual is broadly divided into the following sections.

• CPU functions

• Instruction set

• Explanation of instructions

How to Read This Manual It is assumed that readers of this manual have general knowledge in the fields of

electrical engineering, logic circuits, and microcontrollers.

• To check the details of the functions of an instruction whose mnemonic is known:

→ Refer to APPENDICES B and C.

• To check an instruction whose mnemonic is not known but whose general

function is known:

→ Find the mnemonic in CHAPTER 4 INSTRUCTION SET and then check the

detailed functions in CHAPTER 5 EXPLANATION OF INSTRUCTIONS.

• To learn about the various kinds of 78K/0 Series product instructions in general:

→ Read this manual in the order of CONTENTS.

• To learn about the hardware functions of 78K/0 Series products:

→ See the separate user’s manuals.

Conventions Data significance: Higher digits on the left and lower digits on the right

Note: Footnote for item marked with Note in the text

Caution: Information requiring particular attention

Remark: Supplementary information

Numeral representation: Binary................. XXXX or XXXXB

Decimal .............. XXXX

Hexadecimal...... XXXXH

User's Manual U12326EJ4V0UM

Related Documents

The related documents indicated in this publication may include preliminary versions. However, preliminary

versions are not marked as such.

• Documents Common to 78K/0 Series

Document Name Document No.

User’s Manual Instructions This manual

Application Note

Note

Basic I U12704E

Basic II U10121E

Basic III U10182E

Note Some subseries may not be covered.

Caution The related documents listed above are subject to change without notice. Be sure to use the

latest version of each document for designing.

User's Manual U12326EJ4V0UM

CONTENTS

CHAPTER 1 MEMORY SPACE ...............................................................................................................12

1.1 Memory Spaces ................................................................................................................12

1.2 Internal Program Memory (Internal ROM) Space .......................................................... 12

1.3 Vector Table Area ............................................................................................................. 12

1.4 CALLT Instruction Table Area.........................................................................................12

1.5 CALLF Instruction Entry Area ......................................................................................... 12

1.6 Internal Data Memory (Internal RAM) Space..................................................................12

1.7 Special Function Register (SFR) Area............................................................................13

1.8 External Memory Space ................................................................................................... 13

1.9 IEBus

CHAPTER 2 REGISTERS ........................................................................................................................14

2.1 Control Registers .............................................................................................................14

2.1.1 Program counter (PC) ......................................................................................................... 14

2.1.2 Program status word (PSW) ............................................................................................... 14

2.1.3 Stack pointer (SP)................................................................................................................ 16

2.2 General-Purpose Registers .............................................................................................17

2.3 Special Function Registers (SFRs).................................................................................19

CHAPTER 3 ADDRESSING ..................................................................................................................... 20

3.1 Instruction Address Addressing.....................................................................................20

3.1.1 Relative addressing............................................................................................................. 20

3.1.2 Immediate addressing......................................................................................................... 21

3.1.3 Table indirect addressing ................................................................................................... 22

3.1.4 Register addressing ............................................................................................................ 23

3.2 Operand Address Addressing ........................................................................................ 24

3.2.1 Implied addressing .............................................................................................................. 24

3.2.2 Register addressing ............................................................................................................ 25

3.2.3 Direct addressing ................................................................................................................ 26

3.2.4 Short direct addressing ...................................................................................................... 27

3.2.5 Special-function register (SFR) addressing...................................................................... 28

3.2.6 Register indirect addressing .............................................................................................. 29

3.2.7 Based addressing................................................................................................................ 30

3.2.8 Based indexed addressing ................................................................................................. 30

3.2.9 Stack addressing ................................................................................................................. 31

CHAPTER 4 INSTRUCTION SET ............................................................................................................32

4.1 Operation .......................................................................................................................... 32

4.1.1 Operand identifiers and description methods .................................................................. 32

4.1.2 Description of “operation” column.................................................................................... 33

4.1.3 Description of “flag operation” column ............................................................................ 33

4.1.4 Description of number of clocks........................................................................................ 34

4.1.5 Instructions listed by addressing type .............................................................................. 34

4.2 Instruction Codes ............................................................................................................. 38

4.2.1 Description of instruction code table ................................................................................ 38

4.2.2 Instruction code list............................................................................................................. 39

User's Manual U12326EJ4V0UM

CHAPTER 5 EXPLANATION OF INSTRUCTIONS .................................................................................46

5.1 8-Bit Data Transfer Instructions......................................................................................48

5.2 16-Bit Data Transfer Instructions....................................................................................51

5.3 8-Bit Operation Instructions ............................................................................................ 54

5.4 16-Bit Operation Instructions .......................................................................................... 63

5.5 Multiply/Divide Instructions ............................................................................................ 67

5.6 Increment/Decrement Instructions .................................................................................70

5.7 Rotate Instructions...........................................................................................................75

5.8 BCD Adjust Instructions .................................................................................................. 82

5.9 Bit Manipulation Instructions .......................................................................................... 85

5.10 Call Return Instructions ...................................................................................................93

5.11 Stack Manipulation Instructions ................................................................................... 101

5.12 Unconditional Branch Instruction ................................................................................105

5.13 Conditional Branch Instructions ...................................................................................107

5.14 CPU Control Instructions ..............................................................................................116

APPENDIX A REVISION HISTORY .....................................................................................................123

APPENDIX B INSTRUCTION INDEX (MNEMONIC: BY FUNCTION) ............................................. 124

APPENDIX C INSTRUCTION INDEX (MNEMONIC: IN ALPHABETICAL ORDER) ...................... 126

10 User's Manual U12326EJ4V0UM

LIST OF FIGURES

Figure No. Title Page

2-1 Program Counter Configuration.............................................................................................................. 14

2-2 Program Status Word Configuration....................................................................................................... 14

2-3 Stack Pointer Configuration .................................................................................................................... 16

2-4 Data to Be Saved to Stack Memory ....................................................................................................... 16

2-5 Data to Be Reset from Stack Memory .................................................................................................... 16

2-6 General-Purpose Register Configuration ............................................................................................... 18

LIST OF TABLES

Table No. Title Page

2-1 General-Purpose Register Absolute Address Correspondence Table ..................................................... 17

4-1 Operand Identifiers and Description Methods .......................................................................................... 32

User's Manual U12326EJ4V0UM

CHAPTER 1 MEMORY SPACE

1.1 Memory Spaces

The 78K/0 Series product program memory map varies depending on the internal memory capacity. For details

of memory-mapped address area, refer to the user’s manual of each product.

1.2 Internal Program Memory (Internal ROM) Space

Each 78K/0 Series product has internal ROM in the address space. Program and table data, etc. are stored

in the ROM. Normally, this memory space is addressed by the program counter (PC). For details of the internal

ROM space, refer to the user’s manual of each product.

1.3 Vector Table Area

The 64-byte area 0000H to 003FH is reserved as a vector table area. The program start addresses for branch

upon RESET input or interrupt request generation are stored in the vector table area. Of the 16-bit address, the

lower 8 bits are stored at even addresses and the higher 8 bits are stored at odd addresses. For the vector table

area, refer to the user’s manual of each product.

1.4 CALLT Instruction Table Area

The 64-byte area 0040H to 007FH can store the subroutine entry address of a 1-byte call instruction (CALLT).

1.5 CALLF Instruction Entry Area

The 2048-byte area 0800H to 0FFFH can perform a direct subroutine call with a 2-byte call instruction (CALLF).

1.6 Internal Data Memory (Internal RAM) Space

78K/0 Series products incorporate the following RAMs. For details of these RAMs, refer to the user’s manual

of each product.

(1) Internal high-speed RAM

Each 78K/0 Series product incorporates an internal high-speed RAM. In the 32-byte area FEE0H to FEFFH

of these areas, 4 banks of general-purpose registers, each bank consisting of eight 8-bit registers, are

allocated.

The internal high-speed RAM can also be used as a stack memory.

(2) Buffer RAM

There are some products in the 78K/0 Series to which buffer RAM is allocated. This RAM is used to store

the transfer/receive data of serial interface channel 1 (3-wire serial I/O mode with automatic transfer/receive

function). If not used in this mode, the buffer RAM can also be used as an ordinary RAM area.

User's Manual U12326EJ4V0UM

CHAPTER 1 MEMORY SPACE

(3) RAM for VFD display

There are some products in the 78K/0 Series to which RAM for VFD display is allocated. This RAM can

also be used as an ordinary RAM area.

(4) Internal expansion RAM

There are some products in the 78K/0 Series to which internal expansion RAM is allocated.

(5) RAM for LCD display

There are some products in the 78K/0 Series to which RAM for LCD display is allocated. This RAM can

also be used as an ordinary RAM area.

1.7 Special Function Register (SFR) Area

On-chip peripheral hardware special function registers (SFRs) are allocated in the area FF00H to FFFFH (for

details of the special function registers, refer to the user’s manual of each product).

Caution Do not access addresses to which SFRs are not allocated. If an address is erroneously

accessed, the CPU may become deadlocked.

1.8 External Memory Space

This is an external memory space that can be accessed by setting the memory extension mode register. This

space can store program and table data, and be assigned peripheral devices.

For details of the products in which an external memory space can be used, refer to the user’s manual of each

product.

1.9 IEBusTM Register Area

IEBus registers that are used to control the IEBus controller are allocated to the IEBus register area.

For details of the products that incorporate an IEBus controller, refer to the user’s manual of each product.

User's Manual U12326EJ4V0UM

CHAPTER 2 REGISTERS

2.1 Control Registers

The control registers control the program sequence, statuses and stack memory. A program counter, a program

status word and a stack pointer are the control registers.

2.1.1 Program counter (PC)

The program counter is a 16-bit register that holds the address information of the next program to be executed.

In normal operation, the PC is automatically incremented according to the number of bytes of the instruction

to be fetched. When a branch instruction is executed, immediate data and register contents are set.

RESET input sets the reset vector table values at addresses 0000H and 0001H to the program counter.

Figure 2-1. Program Counter Configuration

15 0

2.1.2 Program status word (PSW)

The program status word is an 8-bit register consisting of various flags to be set/reset by instruction execution.

Program status word contents are automatically stacked upon interrupt request generation or PUSH PSW

instruction execution and are automatically reset upon execution of the RETB, RETI and POP PSW instructions.

RESET input sets the PSW to 02H.

Figure 2-2. Program Status Word Configuration

Z RBS1 AC RBS0 0 ISP CY

User's Manual U12326EJ4V0UM

CHAPTER 2 REGISTERS

(1) Interrupt enable flag (IE)

This flag controls the interrupt request acknowledgement operations of the CPU.

When IE = 0, the IE flag is set to interrupt disable (DI), and interrupts other than non-maskable interrupts

are all disabled.

When IE = 1, the IE flag is set to interrupt enable (EI), and interrupt request acknowledgement is controlled

by an in-service priority flag (ISP), an interrupt mask flag for various interrupt sources, and a priority

specification flag.

This flag is reset (0) upon DI instruction execution or interrupt request acknowledgment and is set (1) upon

execution of the EI instruction.

(2) Zero flag (Z)

When the operation result is zero, this flag is set (1). It is reset (0) in all other cases.

(3) Register bank select flags (RBS0 and RBS1)

These are 2-bit flags used to select one of the four register banks.

In these flags, the 2-bit information that indicates the register bank selected by SBL RBn instruction

execution is stored.

(4) Auxiliary carry flag (AC)

If the operation result has a carry from bit 3 or a borrow at bit 3, this flag is set (1). It is reset (0) in all other

cases.

(5) In-service priority flag (ISP)

This flag manages the priority of acknowledgeable maskable vectored interrupts. When ISP = 0, vectored

interrupt requests specified as low priority by the priority specification flag register (PR) are disabled for

acknowledgment. Actual acknowledgment for interrupt requests is controlled by the state of the interrupt

enable flag (IE).

(6) Carry flag (CY)

This flag stores an overflow or underflow upon add/subtract instruction execution. It stores the shift-out

value upon rotate instruction execution and functions as a bit accumulator during bit manipulation

instruction execution.

User's Manual U12326EJ4V0UM

CHAPTER 2 REGISTERS

2.1.3 Stack pointer (SP)

This is a 16-bit register that holds the start address of the memory stack area. Only the internal high-speed

RAM area can be set as the stack area.

Figure 2-3. Stack Pointer Configuration

15 0

The SP is decremented ahead of write (save) to the stack memory and is incremented after read (reset) from

the stack memory.

Each stack operation saves/resets data as shown in Figures 2-4 and 2-5.

Caution Since RESET input makes SP contents undefined, be sure to initialize the SP before instruction

execution.

Figure 2-4. Data to Be Saved to Stack Memory

SP SP _ 2

SP _ 2

SP _ 1

PUSH rp instruction

Lower half register pairs

Upper half register pairs

Figure 2-5. Data to Be Reset from Stack Memory

instruction

SP SP _ 2

SP _ 2

SP _ 1

CALL, CALLF and CALLT instructions

PC7-PC0

PC15-PC8

RET instructionPOP rp

SP SP _ 3

SP _ 3

SP _ 2

SP _ 1

Interrupt and BRK instructions

PC7-PC0

PC15-PC8

PSW

RETI and RETB instructions

SP SP + 2

SP + 1

Lower half register pairs

Upper half register pairs

SP + 1

SP SP + 2

User's Manual U12326EJ4V0UM

PC7-PC0

PC15-PC8

SP + 1

SP + 2

SP SP + 3

PC7-PC0

PC15-PC8

PSW

CHAPTER 2 REGISTERS

2.2 General-Purpose Registers

General-purpose registers are mapped at particular addresses (FEE0H to FEFFH) of the data memory. These

registers consist of 4 banks, each bank consisting of eight 8-bit registers (X, A, C, B, E, D, L and H).

In addition that each register can be used as an 8-bit register, two 8-bit registers in pairs can be used as a 16-

bit register (AX, BC, DE and HL).

General-purpose registers can be described in terms of functional names (X, A, C, B, E, D, L, H, AX, BC, DE

and HL) and absolute names (R0 to R7 and RP0 to RP3).

of the 4-register bank configuration, an efficient program can be created by switching between a register for normal

processing and a register for processing upon interrupt generation for each bank.

Table 2-1. General-Purpose Register Absolute Address Correspondence Table

Bank Name Register Absolute Address Bank Name Register Absolute Address

Functional Absolute Functional Absolute

Name Name Name Name

BANK0 H R7 FEFFH BANK2 H R7 FEEFH

L R6 FEFEH L R6 FEEEH

D R5 FEFDH D R5 FEEDH

E R4 FEFCH E R4 FEECH

B R3 FEFBH B R3 FEEBH

C R2 FEFAH C R2 FEEAH

A R1 FEF9H A R1 FEE9H

X R0 FEF8H X R0 FEE8H

BANK1 H R7 FEF7H BANK3 H R7 FEE7H

L R6 FEF6H L R6 FEE6H

D R5 FEF5H D R5 FEE5H

E R4 FEF4H E R4 FEE4H

B R3 FEF3H B R3 FEE3H

C R2 FEF2H C R2 FEE2H

A R1 FEF1H A R1 FEE1H

X R0 FEF0H X R0 FEE0H

User's Manual U12326EJ4V0UM

FEFFH

FEF8H FEF7H

FEF0H FEEFH

FEE8H FEE7H

FEE0H

BANK0

BANK1

BANK2

BANK3

CHAPTER 2 REGISTERS

Figure 2-6. General-Purpose Register Configuration

(a) Absolute names

16-bit processing 8-bit processing

RP3

RP2

RP1

RP0

15 0 7 0

FEFFH

FEF8H FEF7H

FEF0H FEEFH

FEE8H FEE7H

FEE0H

BANK0

BANK1

BANK2

BANK3

(b) Functional names

16-bit processing 8-bit processing

15 0 7 0

User's Manual U12326EJ4V0UM

CHAPTER 2 REGISTERS

2.3 Special Function Registers (SFRs)

Unlike a general-purpose register, each special-function register has a special function.

Special function registers are allocated in the 256-byte area FF00H to FFFFH.

Special function registers can be manipulated, like general-purpose registers, by operation, transfer and bit

manipulation instructions. The manipulatable bit units (1, 8, and 16) differ depending on the special function

Each manipulation bit unit can be specified as follows.

• 1-bit manipulation

Describes a symbol reserved by the assembler for the 1-bit manipulation instruction operand (sfr.bit). This

manipulation can also be specified by an address.

• 8-bit manipulation

Describes a symbol reserved by the assembler for the 8-bit manipulation instruction operand (sfr). This

manipulation can also be specified by an address.

• 16-bit manipulation

Describes a symbol reserved by the assembler for the 16-bit manipulation instruction operand (sfrp). When

addressing an address, describe an even address.

For details of the special function registers, refer to the user’s manual of each product.

Caution Do not access addresses to which SFRs are not allocated. If an address is erroneously

accessed, the CPU may become deadlocked.

User's Manual U12326EJ4V0UM

CHAPTER 3 ADDRESSING

3.1 Instruction Address Addressing

An instruction address is determined by program counter (PC) contents. The PC contents are normally

incremented (+1 for each byte) automatically according to the number of bytes of an instruction to be fetched each time another instruction is executed. When a branch instruction is executed, the branch destination information

is set to the PC and branched by the following addressing (for details of each instruction, refer to CHAPTER 5

EXPLANATION OF INSTRUCTIONS).

3.1.1 Relative addressing

[Function]

The value obtained by adding 8-bit immediate data (displacement value: jdisp8) of an instruction code to

the start address of the following instruction is transferred to the program counter (PC) and branched. The displacement value is treated as signed two’s complement data (–128 to +127) and bit 7 becomes a sign

bit. In other words, in relative addressing, the value is relatively transferred to the range between –128 and

+127 from the start address of the following instruction. This function is carried out when the “BR $addr16” instruction or a conditional branch instruction is executed.

[Illustration]

15 0

When S = 0, α indicates all bits "0". When S = 1, α indicates all bits "1".

87 6

jdisp8

...

PC is the start address of the next instruction of a BR instruction.

User's Manual U12326EJ4V0UM

CHAPTER 3 ADDRESSING

3.1.2 Immediate addressing

[Function]

Immediate data in the instruction word is transferred to the program counter (PC) and branched.

This function is carried out when the “CALL !addr16” or “BR !addr16” or “CALLF !addr11” instruction is executed. The CALL !addr16 and BR !addr16 instructions can be branched to all memory spaces. The

CALLF !addr11 instruction is branched to the area of 0800H to 0FFFH.

[Illustration]

CALL !addr16, BR !addr16 instruction

CALL or BR

Low Addr.

High Addr.

CALLF !addr11 instruction

15 0

643

to fa

CALLF

to fa

15 0

11 10

00001

User's Manual U12326EJ4V0UM

CHAPTER 3 ADDRESSING

3.1.3 Table indirect addressing

[Function]

Table contents (branch destination address) of the particular location to be addressed by the lower-5-bit

immediate data of an instruction code from bit 1 to bit 5 are transferred to the program counter (PC) and branched.

When the “CALLT [addr5]” instruction is executed, table indirect addressing is performed. Executing this

instruction enables the value to be branched to all memory spaces referencing the address stored in the memory table of 40H to 7FH.

[Illustration]

765 10

Instruction code

4–0

111

Effective address

Effective address+1

15 1

00000000

Memory (Table)

Low addr.

High addr.

15 0

65 0

User's Manual U12326EJ4V0UM

CHAPTER 3 ADDRESSING

3.1.4 Register addressing

[Function]

The register pair (AX) contents to be specified by an instruction word are transferred to the program counter

(PC) and branched. This function is carried out when the “BR AX” instruction is executed.

[Illustration]

15 0

User's Manual U12326EJ4V0UM

CHAPTER 3 ADDRESSING

3.2 Operand Address Addressing

The following methods are available to specify the register and memory (addressing) to undergo manipulation

during instruction execution.

3.2.1 Implied addressing

[Function]

This addressing automatically specifies the address of the registers that function as an accumulator (A and

AX) in the general-purpose register area.

Of the 78K/0 Series instruction words, the following instructions employ implied addressing.

Instruction Register to Be Specified by Implied Addressing

MULU A register for multiplicand and AX register for product storage

DIVUW AX register for dividend and quotient storage

ADJBA/ADJBS A register for storage of numeric values targeted for decimal correction

ROR4/ROL4 A register for storage of digit data that undergoes digit rotation

[Operand format]

Because implied addressing can be automatically employed with an instruction, no particular operand format is necessary.

[Description example]

In the case of MULU X

With an 8-bit x 8-bit multiply instruction, the product of the A register and X register is stored in AX. In this

example, the A and AX registers are specified by implied addressing.

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CHAPTER 3 ADDRESSING

3.2.2 Register addressing

[Function]

be accessed is specified by the register bank selection flags (RBS0 and RBS1) and the register specification codes (Rn and RPn) in the instruction codes.

an 8-bit register is specified, one of the eight registers is specified by 3 bits in the instruction code.

[Operand format]

Identifier Description

r X, A, C, B, E, D, L, H

rp AX, BC, DE, HL

‘r’ and ‘rp’ can be described with absolute names (R0 to R7 and RP0 to RP3) as well as function names

(X, A, C, B, E, D, L, H, AX, BC, DE and HL).

[Description example]

MOV A, C; When selecting the C register for r

Instruction code 01100010

INCW DE; When selecting the DE register pair for rp

Instruction code 10000100

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CHAPTER 3 ADDRESSING

3.2.3 Direct addressing

[Function]

Direct addressing directly addresses the memory indicated by the immediate data in the instruction word.

[Operand format]

Identifier Description

addr16 Label or 16-bit immediate data

[Description example]

MOV A, !FE00H; When setting !addr16 to FE00H

Instruction code 1 0 001110OP code

0000000000H

11111110FEH

[Illustration]

OP code

addr16 (lower)

addr16 (upper)

Memory

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CHAPTER 3 ADDRESSING

3.2.4 Short direct addressing

[Function]

The memory to be manipulated in the fixed space is directly addressed with 8-bit data in an instruction word.

This addressing is applied to the 256-byte fixed space FE20H to FF1FH. An internal high-speed RAM and special function registers (SFRs) are mapped at FE20H to FEFFH and FF00H to FF1FH, respectively.

The SFR area (FF00H to FF1FH) where short direct addressing is applied is a part of the entire SFR area.

Ports that are frequently accessed in a program, a compare register of the timer/event counter and a capture register of the timer/event counter are mapped in the area FF00H through FF1FH, and these SFRs can be

manipulated with a small number of bytes and clocks.

When 8-bit immediate data is at 20H to FFH, bit 8 of an effective address is set to 0. When it is at 00H to 1FH, bit 8 is set to 1. See [Illustration] below.

[Operand format]

Identifier Description

saddr Label or FE20H to FF1FH immediate data

saddrp Label or FE20H to FF1FH immediate data (even address only)

[Description example]

MOV FE30H, #50H; When setting saddr to FE30H and the immediate data to 50H

Instruction code 00010001OP code

0011000030H (saddr-offset)

0101000050H (immediate data)

[Illustration]

OP code

saddr-offset

Short direct memory

Effective address

111111

When 8-bit immediate data is 20H to FFH, α = 0. When 8-bit immediate data is 00H to 1FH, α = 1.

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CHAPTER 3 ADDRESSING

3.2.5 Special-function register (SFR) addressing

[Function]

A memory-mapped special function register (SFR) is addressed with 8-bit immediate data in an instruction

word. This addressing is applied to the 240-byte spaces FF00H to FFCFH and FFE0H to FFFFH. However, the

SFRs mapped at FF00H to FF1FH can be accessed with short direct addressing.

[Operand format]

Identifier Description

sfr Special function register name

sfrp 16-bit-manipulatable special function register name (even address only)

[Description example]

MOV PM0, A; When selecting PM0 for sfr

Instruction code 11110110OP code

[Illustration]

Effective address

OP code

sfr-offset

111111

0010000020H (sfr-offset)

SFR

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CHAPTER 3 ADDRESSING

3.2.6 Register indirect addressing

[Function]

register pair to be accessed is specified by the register bank selection flags (RBS0 and RBS1) and the register pair specification in instruction codes.

[Operand format]

Identifier Description

—

[DE], [HL]

[Description example]

MOV A, [DE]; When selecting register pair [DE]

Instruction code 10000101

[Illustration]

15 08D7

Contents of memory to be addressed are transferred

7 0

Memory

Memory address specified by register pair DE

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CHAPTER 3 ADDRESSING

3.2.7 Based addressing

[Function]

8-bit immediate data is added to the contents of the HL register pair as a base register and the sum is used

to address the memory. The HL register pair to be accessed is in the register bank specified by the register bank select flag (RBS0 and RBS1). Addition is performed by expanding the offset data as a positive number

to 16 bits. A carry from the 16th bit is ignored. This addressing can be carried out for all the memory spaces.

[Operand format]

Identifier Description

—

[HL+byte]

[Description example]

MOV A, [HL+10H]; When setting byte to 10H

Instruction code 10101110

00010000

3.2.8 Based indexed addressing

[Function]

The B or C register contents specified in an instruction word are added to the contents of the HL register

pair as a base register and the sum is used to address the memory. The HL, B, and C registers to be accessed

are registers in the register bank specified by the register bank select flag (RBS0 to RBS1). Addition is performed by expanding the B or C register as a positive number to 16 bits. A carry from the 16th bit is

ignored. This addressing can be carried out for all the memory spaces.

[Operand format]

Identifier Description

—

[HL+B], [HL+C]

[Description example]

In the case of MOV A, [HL+B]

Instruction code 10101011

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