Operand Summary; Second Instruction Byte Summary - IBM XT 5160 Technical Reference

AF Auxiliary Carry - BCD
CF Carry Flag
PF Parity Flag
SF Sign Flag
ZF Zero Flag
} 8080
Flags
DF: Direction Flag }
IF: Interrupt Enable Flag 8088 Flags
OF: Overflow Flag (CF
+
SF)
TF: Trap-Single Step Flag
Operand Summary
reg Field Bit Assignments
16-Bit [w = 1] 8-B i t [w = 0] Segment
000 AX 000 AL 00 ES
001 CX 001 CL 01 CS
010 DX 010 DL 10 SS
all
BX
all
BL 11 DS
100 SP 100
AH
101 BP 101 CH
110 SI 110 DH
111 DI 111 BH
Second Instruction Byte Summary
~r/m
mod Displacement
00 DISP = 0*, disp-low and disp-high are absent
01 DISP = disp-low sign-extended to 16-bits, disp-high is absent
10 DISP = disp-high:
di~p-1Rw
.
11 rim is treated as a reg field
DISP follows 2nd byte of instruction (before data if required)
*except if mod=OO and r/m-110 then EA=disp-high: disp-low.
6-4 Instruction Set