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This HTML version of the file intel.doc from the
PC Game Programmer's guide was produced by Zack T Smith. Fancy HTML modifications are copyright ©
2005 by Zack T Smith, all rights reserved.
This information is provided in the hope that it will be useful,
but without any warranty. It is provided AS-IS,
without even the implied warranty of fitness for a particular purpose.
M Instructions
MOV - Move Byte or Word
Usage: MOV dest,src
Modifies flags: None
Copies byte or word from the source operand to the destination
operand. If the destination is SS interrupts are disabled except
on early buggy 808x CPUs. Some CPUs disable interrupts if the
destination is any of the segment registers
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg 2 2 2 1 2
mem,reg 9+EA 3 2 1 2-4 (W88=13+EA)
reg,mem 8+EA 5 4 1 2-4 (W88=12+EA)
mem,immed 10+EA 3 2 1 3-6 (W88=14+EA)
reg,immed 4 2 2 1 2-3
mem,accum 10 3 2 1 3 (W88=14)
accum,mem 10 5 4 1 3 (W88=14)
segreg,reg16 2 2 2 3 2
segreg,mem16 8+EA 5 5 9 2-4 (W88=12+EA)
reg16,segreg 2 2 2 3 2
mem16,segreg 9+EA 3 2 3 2-4 (W88=13+EA)
reg32,CR0/CR2/CR3 - - 6 4
CR0,reg32 - - 10 16
CR2,reg32 - - 4 4 3
CR3,reg32 - - 5 4 3
reg32,DR0/DR1/DR2/DR3 - 22 10 3
reg32,DR6/DR7 - - 22 10 3
DR0/DR1/DR2/DR3,reg32 - 22 11 3
DR6/DR7,reg32 - - 16 11 3
reg32,TR6/TR7 - - 12 4 3
TR6/TR7,reg32 - - 12 4 3
reg32,TR3 3
TR3,reg32 6
- when the 386 special registers are used all operands are 32 bits
MOVS - Move String (Byte or Word)
Usage: MOVS dest,src
MOVSB
MOVSW
MOVSD (386+)
Modifies flags: None
Copies data from addressed by DS:SI (even if operands are given) to
the location ES:DI destination and updates SI and DI based on the
size of the operand or instruction used. SI and DI are incremented
when the Direction Flag is cleared and decremented when the Direction
Flag is Set. Use with REP prefixes.
Clocks Size
Operands 808x 286 386 486 Bytes
dest,src 18 5 7 7 1 (W88=26)
MOVSX - Move with Sign Extend (386+)
Usage: MOVSX dest,src
Modifies flags: None
Copies the value of the source operand to the destination register
with the sign extended.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg - - 3 3 3
reg,mem - - 6 3 3-7
MOVZX - Move with Zero Extend (386+)
Usage: MOVZX dest,src
Modifies flags: None
Copies the value of the source operand to the destination register
with the zeroes extended.
Clocks Size
Operands 808x 286 386 486 Bytes
reg,reg - - 3 3 3
reg,mem - - 6 3 3-7
MUL - Unsigned Multiply
Usage: MUL src
Modifies flags: CF OF (AF,PF,SF,ZF undefined)
Unsigned multiply of the accumulator by the source. If "src" is
a byte value, then AL is used as the other multiplicand and the
result is placed in AX. If "src" is a word value, then AX is
multiplied by "src" and DX:AX receives the result. If "src" is
a double word value, then EAX is multiplied by "src" and EDX:EAX
receives the result. The 386+ uses an early out algorithm which
makes multiplying any size value in EAX as fast as in the 8 or 16
bit registers.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 70-77 13 9-14 13-18 2
reg16 118-113 21 9-22 13-26 2
reg32 - - 9-38 13-42 2-4
mem8 (76-83)+EA 16 12-17 13-18 2-4
mem16 (124-139)+EA 24 12-25 13-26 2-4
mem32 - - 12-21 13-42 2-4
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