Processor Control - IBM 5150 Technical Reference

Processor Control
CLC
=
Clear carry
STC
=
Set carry
1 1 1 1 1 0 0 0
1 1 1 1 1 0 0
CMC = Complement carry
NOP
=
No operation
1 1 1 1 0 1 0
1 0 0 1 0 0 0 0
CLD
=
Clear direction STD
=
Set direction
1 1 1 1 1 1 0 0
1 1 1 1 0
CLI
=
Clear interrupt
STI = Set interrupt
1 1 1 1 1 0 1 0 1 1 1
o
1
HLT = Halt WAIT
=
Wait
1 1 1 1 0 1 0 0
1 0 0 1 1 0 1 1
LOCK
=
Bus lock prefix ESC = Escape (to external device)
1 1 1 1 0 0 0 0 1 0 1 1 x x x 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