IBM 5150 - Processor Control

Processor Control
CLC = Clear carry
STC
= Set carry
11111000
1111100
CMC = Complement carry
NOP
= No operation
1111010
100 1 0 000
CLD = Clear direction
STD
= Set direction
11111100
1 1 1 1 0
CLI
= Clear interrupt
STI
= Set interrupt
11111010 1 1 1
o 1
HLT = Halt WAIT = Wait
11110100
10011011
LOCK = Bus lock prefix ESC = Escape (to external device)
11110000 1011xxx
mod x x x
rim
Footnotes:
if d = 1 then "to"; if d = 0 then "from"
if w = 1 then word instruction; if w = 0 then byte instruction
if s:w = 01 then 16 bits of immediate data from the operand
if s:w = 11 then an immediate data byte is signed extended to form the 16-bit operand
if v = Othen "count" = 1; if v = 1 then "count" in (Cl)
x = don't care
z is used
for some string primitives to compare with ZF FLAG
AL =8-bit accumulator
AX = 16-bit accumulator
CX
= Count register
DS = Data segment
DX
= Variable port register
ES = Extra segment
Above/below refers to unsigned value
Greater
= more positive;
less = less positive (more negative) signed values
6-16 Instruction Set