APPENDIX D

INSTRUCTION SET OPCODES

AND CLOCK CYCLES

This appendix provides reference information for the 80C186 Modular Core family instruction set. Table D-1 defines the variables used in Table D-2, which lists the instructions with their for- mats and execution times. Table D-3 is a guide for decoding machine instructions. Table D-4 is

aguide for encoding instruction mnemonics, and Table D-5 defines Table D-4 abbreviations.

Table D-1. Operand Variables

Variable

Description

 

 

mod

mod and r/m determine the Effective Address (EA).

 

 

r/m

r/m and mod determine the Effective Address (EA).

 

 

reg

reg represents a register.

 

 

MMM

MMM and PPP are opcodes to the math coprocessor.

 

 

PPP

PPP and MMM are opcodes to the math coprocessor.

 

 

TTT

TTT defines which shift or rotate instruction is executed.

 

 

r/m

EA Calculation

 

 

0 0 0

(BX) + (SI) + DISP

 

 

0 0 1

(BX) + (DI) + DISP

 

 

0 1 0

(BP) + (SI) + DISP

 

 

0 1 1

(BP) + (DI) + DISP

 

 

1 0 0

(SI) + DISP

 

 

1 0 1

(DI) + DISP

 

 

1 1 0

(BP) + DISP, if mod 00

 

disp-high:disp-low, if mod =00

 

 

1 1 1

(BX) + DISP

 

 

mod

Effect on EA Calculation

 

 

0 0

if r/m 110, DISP = 0; disp-low and disp-high are absent

 

 

0 0

if r/m = 110, EA = disp-high:disp-low

 

 

0 1

DISP = disp-low, sign-extended to 16 bits; disp-high is absent

 

 

1 0

DISP = disp-high:disp-low

 

 

1 1

r/m is treated as a reg field

 

 

DISP follows the second byte of the instruction (before any required data).

Physical addresses of operands addressed by the BP register are computed using the SS segment register. Physical addresses of destination operands of string primitives (addressed by the DI register) are computed using the ES seg- ment register, which cannot be overridden.

reg

16-bit (w=1)

8-bit (w=0)

 

TTT

Instruction

 

 

 

 

 

 

0 0 0

AX

AL

 

0 0 0

ROL

 

 

 

 

 

 

0 0 1

CX

CL

 

0 0 1

ROR

 

 

 

 

 

 

0 1 0

DX

DL

 

0 1 0

RCL

 

 

 

 

 

 

0 1 1

BP

BL

 

0 1 1

RCR

 

 

 

 

 

 

1 0 0

SP

AH

 

1 0 0

SHL/SAL

 

 

 

 

 

 

1 0 1

BP

CH

 

1 0 1

SHR

 

 

 

 

 

 

1 1 0

SI

DH

 

1 1 0

 

 

 

 

 

 

1 1 1

DI

BH

 

1 1 1

SAR

 

 

 

 

 

 

D-1

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Intel 80C188XL, 80C186XL Table D-1. Operand Variables, Mod Effect on EA Calculation, Reg Bit w=1 Bit w=0, Instruction