Tandy 1000 HX Technical Reference Manual page 111

8088
8086/8088 Instruction Set Summary (Continued)
NOTES:
AL = 8-bit accumulator
AX = 16-bit accumulator
CX = Count register
DS = Data segment
ES = Extra segment
Above/below refers to unsigned value
Greater = more positive:
Less = less positive (more negative) signed values
if d = 1 then "to" reg; if d = 0 then "from" reg
if w = 1 then word instruction; if w = 0 then byte
instruction
if mod = 11 then r/m is treated as a REG field
if mod = 00 then DISP = 0*, disp-low and disp-high are
absent
if mod = 01 then DISP = disp-low sign-extended to
16 bits, disp-high is absent
if mod = 10 then DISP = disp-high; disp-low
if r/m = 000 then EA = (BX) + (SI) + DISP
if r/m = 001 then EA = (BX) + (Dl) + DISP
if r/m = 010 then EA = (BP) + (SI) + DISP
if r/m = 011 then EA = (BP) + (Dl) + DISP
if r/m = 100 then EA = (SI) + DISP
if r/m = 101 then EA = (Dl) + DISP
if r/m = 110 then EA = (BP) + DISP*
if r/m = 111 then EA = (BX) + DISP
DISP follows 2nd byte of instruction (before data if re-
quired)
•except if mod = 00 and r/m = then EA = disp-high:
disp-low.
if s:w = 01 then 16 bits of immediate data form the oper-
and
if s:w = 11 then an immediate data byte is sign extended
to form the 16-bit operand
if v = 0 then "count" = 1; if v = 1 then "count" in (CL)
register
x = don't care
z is used for string primitives for comparison with ZF FLAG
SEGMENT OVERRIDE PREFIX
I 0 0 1 reg 1 1 0 I
REG is assigned according to the following table:
16-Bit ( w = 1)
000
001
010
011
100
101
110
111
AX
CX
DX
BX
SP
BP
SI
Dl
8-Bit (w = 0)
000
001
010
011
100
101
110
111
AL
CL
DL
BL
AH
CH
DH
BH
Segment
00 ES
01 CS
10 SS
11 DS
Instructions which reference the flag register file as a 16-bit
object use the symbol FLAGS to represent the file:
FLAGS =
X:X:X:X:(OF):(DF):(IF):(TF):(SF):(ZF):X:(AF):X:(PF):X:(CF)
Mnemonics © Intel, 1978
All mnemonics copyright Intel Corporation 1987.
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