C-17
INSTRUCTION SET DESCRIPTIONS
IMUL
Integer Multiply:
IMUL
src
Performs a signed multiplication of the
source operand and the accumulator.
If the source is a byte, then it is
multiplied by register AL, and the
double-length result is returned in AH
and AL. If the source is a word, then it
is multiplied by register AX, and the
double-length result is returned in
registers DX and AX. If the upper half
of the result (AH for byte source, DX
for word source) is not the sign
extension of the lower half of the
result, CF and OF are set; otherwise
they are cleared. When CF and OF are
set, they indicate that AH or DX
contains significant digits of the result.
Instruction Operands:
IMUL reg
IMUL mem
IMUL immed
When Source Operand is a Byte:
(AX)
←
(byte-src) × (AL)
if
(AH) = sign-extension of (AL)
then
(CF)
←
0
else
(CF)
←
1
(OF)
←
(CF)
When Source Operand is a Word:
(DX:AX)
←
(word-src) × (AX)
if
(DX) = sign-extension of (AX)
then
(CF)
←
0
else
(CF)
←
1
(OF)
←
(CF)
AF ?
CF
ü
DF –
IF –
OF
ü
PF ?
SF ?
TF –
ZF ?
IN
Input Byte or Word:
IN accum, port
Transfers a byte or a word from an
input port to the AL register or the AX
register, respectively. The port number
may be specified either with an
immediate byte constant, allowing
access to ports numbered 0 through
255, or with a number previously
placed in the DX register, allowing
variable access (by changing the value
in DX) to ports numbered from 0
through 65,535.
Instruction Operands:
IN AL, immed8
IN AX, DX
When Source Operand is a Byte:
(AL)
←
(port)
When Source Operand is a Word:
(AX)
←
(port)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
Table C-4. Instruction Set (Continued)
Name
Description
Operation
Flags
Affected
NOTE: The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed
ü
the flag is updated after the instruction is executed
Содержание 80C186EA
Страница 1: ...80C186EA 80C188EA Microprocessor User s Manual...
Страница 2: ...80C186EA 80C188EA Microprocessor User s Manual 1995...
Страница 19: ......
Страница 20: ...1 Introduction...
Страница 21: ......
Страница 28: ...2 Overview of the 80C186 Family Architecture...
Страница 29: ......
Страница 79: ......
Страница 80: ...3 Bus Interface Unit...
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Страница 130: ...4 Peripheral Control Block...
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Страница 140: ...5 ClockGenerationand Power Management...
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Страница 166: ...6 Chip Select Unit...
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Страница 190: ...7 Refresh Control Unit...
Страница 191: ......
Страница 205: ......
Страница 206: ...8 Interrupt Control Unit...
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Страница 239: ...INTERRUPT CONTROL UNIT 8 32...
Страница 240: ...9 Timer Counter Unit...
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Страница 265: ......
Страница 266: ...10 Direct Memory Access Unit...
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Страница 295: ...DIRECT MEMORY ACCESS UNIT 10 28...
Страница 296: ...11 Math Coprocessing...
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Страница 314: ...12 ONCE Mode...
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Страница 318: ...A 80C186 Instruction Set Additions and Extensions...
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Страница 330: ...B Input Synchronization...
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Страница 334: ...C Instruction Set Descriptions...
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Страница 383: ...INSTRUCTION SET DESCRIPTIONS C 48...
Страница 384: ...D Instruction Set Opcodes and Clock Cycles...
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Страница 408: ...Index...
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