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How to Read the Instruction Set Chart
In order to use the chart, you need to learn the meanings of the
specifiers (each given by 2 lower case letters) that follow most
of the instruction mnemonics. Each specifier indicates the type
of operand (register byte, immediate word, etc.) that follows
the mnemonic to produce the given opcodes.
"c" means the operand is a code label, pointing to a part of the
program to be jumped to or called. Operands will also accept a
constant offset in this place (or a constant segment-offset
pair in the case of "cd"). "cb" is a label within about 128
bytes (in either direction) of the current location. "cw" is
a label within the same code segment as this program; "cd" is
a pair of constants separated by a colon-- the segment value
to the left of the colon, and the offset to the right. Note
that in both the cb and cw cases, the object code generated
is the offset from the location following the current
instruction, not the absolute location of the label operand.
In some assemblers (most notably for the Z-80 processor) you
have to code this offset explicitly by putting "$-" before
every relative jump operand in your source code.
"e" means the operand is an Effective Address. The concept of
an Effective Address is central to the 86 machine
architecture, and thus to 86 assembly language programming.
It is described in detail at the start of this chapter. We
summarize here by saying that an Effective Address is either
a general purpose register, a memory variable, or an indexed
memory quantity. For example, the instruction "ADD rb,eb"
includes the instructions: ADD AL,BL, and ADD CH,BYTEVAR, and
ADD DL,B[BX+17].
"i" means the operand is an immediate constant, provided as part
of the instruction itself. "ib" is a byte-sized constant;
"iw" is a constant occupying a full 16-bit word. The operand
can also be a label, defined with a colon. In that case, the
immediate constant which is the location of the label is
used. Examples: "MOV rw,iw" includes the instructions: MOV
AX,17, or MOV SI,VAR_ARRAY, where "VAR_ARRAY:" appears
somewhere in the program, defined with a colon. NOTE that if
VAR_ARRAY were defined without a colon, e.g., "VAR_ARRAY DW
1,2,3", then "MOV SI,VAR_ARRAY" would be a "MOV rw,ew" NOT a
"MOV rw,iw". The MOV would move the contents of memory at
VAR_ARRAY (in this case 1) into SI, instead of the location
of the memory. To load the location, you can code "MOV
SI,OFFSET VAR_ARRAY".
"m" means a memory variable or an indexed memory quantity; i.e.,
any Effective Address EXCEPT a register.
"r" means the operand is a general purpose register. The 8 "rb"
registers are AL,BL,CL,DL,AH,BH,CH,DH; the 8 "rw" registers
are AX,BX,CX,DX,SI,DI,BP,SP.
WARNING: Instruction forms marked with "*" by the mnemonic are
part of the extended 186/286/NEC instruction set. Instructions
marked with "#" are unique to the NEC processors. These
instructions will NOT work on the 8088 of the IBM-PC; nor will
they work on the 8086; nor will the NEC instructions work on the
186 or 286. If you wish your programs to run on all PC's, do not
use these instructions!
Opcodes Instruction Description
37 AAA ASCII adjust AL (carry into AH) after addition
D5 0A AAD ASCII adjust before division (AX = 10*AH + AL)
D4 0A AAM ASCII adjust after multiply (AL/10: AH=Quo AL=Rem)
3F AAS ASCII adjust AL (borrow from AH) after subtraction
14 ib ADC AL,ib Add with carry immediate byte into AL
15 iw ADC AX,iw Add with carry immediate word into AX
80 /2 ib ADC eb,ib Add with carry immediate byte into EA byte
10 /r ADC eb,rb Add with carry byte register into EA byte
83 /2 ib ADC ew,ib Add with carry immediate byte into EA word
81 /2 iw ADC ew,iw Add with carry immediate word into EA word
11 /r ADC ew,rw Add with carry word register into EA word
12 /r ADC rb,eb Add with carry EA byte into byte register
13 /r ADC rw,ew Add with carry EA word into word register
04 ib ADD AL,ib Add immediate byte into AL
05 iw ADD AX,iw Add immediate word into AX
80 /0 ib ADD eb,ib Add immediate byte into EA byte
00 /r ADD eb,rb Add byte register into EA byte
83 /0 ib ADD ew,ib Add immediate byte into EA word
81 /0 iw ADD ew,iw Add immediate word into EA word
01 /r ADD ew,rw Add word register into EA word
02 /r ADD rb,eb Add EA byte into byte register
03 /r ADD rw,ew Add EA word into word register
0F 20 #ADD4S Add CL nibbles BCD from DS:SI into ES:DI (CL even,NZ)
24 ib AND AL,ib Logical-AND immediate byte into AL
25 iw AND AX,iw Logical-AND immediate word into AX
80 /4 ib AND eb,ib Logical-AND immediate byte into EA byte
20 /r AND eb,rb Logical-AND byte register into EA byte
83 /4 ib AND ew,ib Logical-AND immediate byte into EA word
81 /4 iw AND ew,iw Logical-AND immediate word into EA word
21 /r AND ew,rw Logical-AND word register into EA word
22 /r AND rb,eb Logical-AND EA byte into byte register
23 /r AND rw,ew Logical-AND EA word into word register
63 /r *ARPL ew,rw Adjust RPL of EA word not smaller than RPL of rw
62 /r *BOUND rw,md INT 5 if rw not between [md] and [md+2] inclusive
9A cd CALL cd Call far segment, immediate 4-byte address
E8 cw CALL cw Call near, offset relative to next instruction
FF /3 CALL ed Call far segment, address at EA doubleword
FF /2 CALL ew Call near, offset absolute at EA word
0F FF ib #CALL80 ib Call 8080-emulation code at INT number ib
98 CBW Convert byte into word (AH = top bit of AL)
F8 CLC Clear carry flag
FC CLD Clear direction flag so SI and DI will increment
FA CLI Clear interrupt enable flag; interrupts disabled
0F 12/0 #CLRBIT eb,CL Clear bit CL of eb
0F 13/0 #CLRBIT ew,CL Clear bit CL of ew
0F 1A/0 ib #CLRBIT eb,ib Clear bit ib of eb
0F 1B/0 ib #CLRBIT ew,ib Clear bit ib of ew
0F 06 *CLTS Clear task switched flag
F5 CMC Complement carry flag
3C ib CMP AL,ib Subtract immediate byte from AL for flags only
3D iw CMP AX,iw Subtract immediate word from AX for flags only
80 /7 ib CMP eb,ib Subtract immediate byte from EA byte for flags only
38 /r CMP eb,rb Subtract byte register from EA byte for flags only
83 /7 ib CMP ew,ib Subtract immediate byte from EA word for flags only
81 /7 iw CMP ew,iw Subtract immediate word from EA word for flags only
39 /r CMP ew,rw Subtract word register from EA word for flags only
3A /r CMP rb,eb Subtract EA byte from byte register for flags only
3B /r CMP rw,ew Subtract EA word from word register for flags only
0F 26 #CMP4S Compare CL nibbles CD at DS:SI from ES:DI (CL even,NZ)
A6 CMPS mb,mb Compare bytes ES:[DI] from [SI], advance SI and DI
A7 CMPS mw,mw Compare words ES:[DI] from [SI], advance SI and DI
A6 CMPSB Compare bytes ES:[DI] from DS:[SI], advance SI and DI
A7 CMPSW Compare words ES:[DI] from DS:[SI], advance SI and DI
99 CWD Convert word to doubleword (DX = top bit of AX)
27 DAA Decimal adjust AL after addition
2F DAS Decimal adjust AL after subtraction
FE /1 DEC eb Decrement EA byte by 1
FF /1 DEC ew Decrement EA word by 1
48+rw DEC rw Decrement word register by 1
F6 /6 DIV eb Unsigned divide AX by EA byte (AL=Quo AH=Rem)
F7 /6 DIV ew Unsigned divide DXAX by EA word (AX=Quo DX=Rem)
C8 iw 00 *ENTER iw,0 Make stack frame, iw bytes local storage, 0 levels
C8 iw 01 *ENTER iw,1 Make stack frame, iw bytes local storage, 1 level
C8 iw ib *ENTER iw,ib Make stack frame, iw bytes local storage, ib levels
F4 HLT Halt
F6 /7 IDIV eb Signed divide AX by EA byte (AL=Quo AH=Rem)
F7 /7 IDIV ew Signed divide DXAX by EA word (AX=Quo DX=Rem)
F6 /5 IMUL eb Signed multiply (AX = AL * EA byte)
F7 /5 IMUL ew Signed multiply (DXAX = AX * EA word)
6B /r ib *IMUL rw,ib Signed multiply immediate byte into word register
69 /r iw *IMUL rw,iw Signed multiply immediate word into word register
69 /r iw *IMUL rw,ew,iw Signed multiply (rw = EA word * immediate word)
6B /r ib *IMUL rw,ew,ib Signed multiply (rw = EA word * immediate byte)
E4 ib IN AL,ib Input byte from immediate port into AL
EC IN AL,DX Input byte from port DX into AL
E5 ib IN AX,ib Input word from immediate port into AX
ED IN AX,DX Input word from port DX into AX
FE /0 INC eb Increment EA byte by 1
FF /0 INC ew Increment EA word by 1
40+rw INC rw Increment word register by 1
6C *INS eb,DX Input byte from port DX into [DI]
6D *INS ew,DX Input word from port DX into [DI]
6C *INSB Input byte from port DX into ES:[DI]
6D *INSW Input word from port DX into ES:[DI]
CC INT 3 Interrupt 3 (trap to debugger) (far call, with flags
CD ib INT ib Interrupt numbered by immediate byte pushed first)
CE INTO Interrupt 4 if overflow flag is 1
CF IRET Interrupt return (far return and pop flags)
77 cb JA cb Jump short if above (CF=0 and ZF=0) above=UNSIGNED
73 cb JAE cb Jump short if above or equal (CF=0)
72 cb JB cb Jump short if below (CF=1) below=UNSIGNED
76 cb JBE cb Jump short if below or equal (CF=1 or ZF=1)
72 cb JC cb Jump short if carry (CF=1)
E3 cb JCXZ cb Jump short if CX register is zero
74 cb JE cb Jump short if equal (ZF=1)
7F cb JG cb Jump short if greater (ZF=0 and SF=OF) greater=SIGNED
7D cb JGE cb Jump short if greater or equal (SF=OF)
7C cb JL cb Jump short if less (SF/=OF) less=SIGNED
7E cb JLE cb Jump short if less or equal (ZF=1 or SF/=OF)
EB cb JMP cb Jump short (signed byte relative to next instruction)
EA cd JMP cd Jump far (4-byte immediate address)
E9 cw JMP cw Jump near (word offset relative to next instruction)
FF /4 JMP ew Jump near to EA word (absolute offset)
FF /5 JMP md Jump far (4-byte address in memory doubleword)
76 cb JNA cb Jump short if not above (CF=1 or ZF=1)
72 cb JNAE cb Jump short if not above or equal (CF=1)
73 cb JNB cb Jump short if not below (CF=0)
77 cb JNBE cb Jump short if not below or equal (CF=0 and ZF=0)
73 cb JNC cb Jump short if not carry (CF=0)
75 cb JNE cb Jump short if not equal (ZF=0)
7E cb JNG cb Jump short if not greater (ZF=1 or SF/=OF)
7C cb JNGE cb Jump short if not greater or equal (SF/=OF)
7D cb JNL cb Jump short if not less (SF=OF)
7F cb JNLE cb Jump short if not less or equal (ZF=0 and SF=OF)
71 cb JNO cb Jump short if not overflow (OF=0)
7B cb JNP cb Jump short if not parity (PF=0)
79 cb JNS cb Jump short if not sign (SF=0)
75 cb JNZ cb Jump short if not zero (ZF=0)
70 cb JO cb Jump short if overflow (OF=1)
7A cb JP cb Jump short if parity (PF=1)
7A cb JPE cb Jump short if parity even (PF=1)
7B cb JPO cb Jump short if parity odd (PF=0)
78 cb JS cb Jump short if sign (SF=1)
74 cb JZ cb Jump short if zero (ZF=1)
9F LAHF Load: AH = flags SF ZF xx AF xx PF xx CF
0F 02 /r *LAR rw,ew Load: high(rw) = Access Rights byte, selector ew
C5 /r LDS rw,ed Load EA doubleword into DS and word register
8D /r LEA rw,m Calculate EA offset given by m, place in rw
C9 *LEAVE Set SP to BP, then POP BP (reverses previous ENTER)
C4 /r LES rw,ed Load EA doubleword into ES and word register
0F 01 /2 *LGDT m Load 6 bytes at m into Global Descriptor Table reg
0F 01 /3 *LIDT m Load 6 bytes at m into Interrupt Descriptor Table reg
0F 00 /2 *LLDT ew Load selector ew into Local Descriptor Table reg
0F 01 /6 *LMSW ew Load EA word into Machine Status Word
F0 LOCK (prefix) Assert BUSLOCK signal for the next instruction
0F 33/r #LODBITS rb,rb Load AX with DS:SI,bit rb (incr. SI,rb), rb+1 bits
0F 3B/0 ib #LODBITS rb,ib Load AX with DS:SI,bit rb (incr. SI,rb), ib+1 bits
AC LODS mb Load byte [SI] into AL, advance SI
AD LODS mw Load word [SI] into AX, advance SI
AC LODSB Load byte [SI] into AL, advance SI
AD LODSW Load word [SI] into AX, advance SI
E2 cb LOOP cb noflags DEC CX; jump short if CX/=0
E1 cb LOOPE cb noflags DEC CX; jump short if CX/=0 and equal (ZF=1)
E0 cb LOOPNE cb noflags DEC CX; jump short if CX/=0 and not equal
E0 cb LOOPNZ cb noflags DEC CX; jump short if CX/=0 and ZF=0
E1 cb LOOPZ cb noflags DEC CX; jump short if CX/=0 and zero (ZF=1)
0F 03 /r *LSL rw,ew Load: rw = Segment Limit, selector ew
0F 00 /3 *LTR ew Load EA word into Task Register
A0 iw MOV AL,xb Move byte variable (offset iw) into AL
A1 iw MOV AX,xw Move word variable (offset iw) into AX
8E /3 MOV DS,mw Move memory word into DS
8E /3 MOV DS,rw Move word register into DS
C6 /0 ib MOV eb,ib Move immediate byte into EA byte
88 /r MOV eb,rb Move byte register into EA byte
8E /0 MOV ES,mw Move memory word into ES
8E /0 MOV ES,rw Move word register into ES
8C /1 MOV ew,CS Move CS into EA word
8C /3 MOV ew,DS Move DS into EA word
C7 /0 iw MOV ew,iw Move immediate word into EA word
8C /0 MOV ew,ES Move ES into EA word
89 /r MOV ew,rw Move word register into EA word
8C /2 MOV ew,SS Move SS into EA word
B0+rb ib MOV rb,ib Move immediate byte into byte register
8A /r MOV rb,eb Move EA byte into byte register
B8+rw iw MOV rw,iw Move immediate word into word register
8B /r MOV rw,ew Move EA word into word register
8E /2 MOV SS,mw Move memory word into SS
8E /2 MOV SS,rw Move word register into SS
A2 iw MOV xb,AL Move AL into byte variable (offset iw)
A3 iw MOV xw,AX Move AX into word register (offset iw)
A4 MOVS mb,mb Move byte [SI] to ES:[DI], advance SI and DI
A5 MOVS mw,mw Move word [SI] to ES:[DI], advance SI and DI
A4 MOVSB Move byte DS:[SI] to ES:[DI], advance SI and DI
A5 MOVSW Move word DS:[SI] to ES:[DI], advance SI and DI
F6 /4 MUL eb Unsigned multiply (AX = AL * EA byte)
F7 /4 MUL ew Unsigned multiply (DXAX = AX * EA word)
F6 /3 NEG eb Two's complement negate EA byte
F7 /3 NEG ew Two's complement negate EA word
90 NOP No Operation
F6 /2 NOT eb Reverse each bit of EA byte
F7 /2 NOT ew Reverse each bit of EA word
0F 16/0 #NOTBIT eb,CL Complement bit CL of eb
0F 17/0 #NOTBIT ew,CL Complement bit CL of ew
0F 1E/0 ib #NOTBIT eb,ib Complement bit ib of eb
0F 1F/0 ib #NOTBIT ew,ib Complement bit ib of ew
0C ib OR AL,ib Logical-OR immediate byte into AL
0D iw OR AX,iw Logical-OR immediate word into AX
80 /1 ib OR eb,ib Logical-OR immediate byte into EA byte
08 /r OR eb,rb Logical-OR byte register into EA byte
83 /1 ib OR ew,ib Logical-OR immediate byte into EA word
81 /1 iw OR ew,iw Logical-OR immediate word into EA word
09 /r OR ew,rw Logical-OR word register into EA word
0A /r OR rb,eb Logical-OR EA byte into byte register
0B /r OR rw,ew Logical-OR EA word into word register
E6 ib OUT ib,AL Output byte AL to immediate port number ib
E7 ib OUT ib,AX Output word AX to immediate port number ib
EE OUT DX,AL Output byte AL to port number DX
EF OUT DX,AX Output word AX to port number DX
6E *OUTS DX,eb Output byte [SI] to port number DX, advance SI
6F *OUTS DX,ew Output word [SI] to port number DX, advance SI
6E *OUTSB Output byte DS:[SI] to port number DX, advance SI
6F *OUTSW Output word DS:[SI] to port number DX, advance SI
1F POP DS Set DS to top of stack, increment SP by 2
07 POP ES Set ES to top of stack, increment SP by 2
8F /0 POP mw Set memory word to top of stack, increment SP by 2
58+rw POP rw Set word register to top of stack, increment SP by 2
17 POP SS Set SS to top of stack, increment SP by 2
61 *POPA Pop DI,SI,BP,SP,BX,DX,CX,AX (SP value is ignored)
9D POPF Set flags register to top of stack, increment SP by 2
0E PUSH CS Set [SP-2] to CS, then decrement SP by 2
1E PUSH DS Set [SP-2] to DS, then decrement SP by 2
06 PUSH ES Set [SP-2] to ES, then decrement SP by 2
6A ib *PUSH ib Push sign-extended immediate byte
68 iw *PUSH iw Set [SP-2] to immediate word, then decrement SP by 2
FF /6 PUSH mw Set [SP-2] to memory word, then decrement SP by 2
50+rw PUSH rw Set [SP-2] to word register, then decrement SP by 2
16 PUSH SS Set [SP-2] to SS, then decrement SP by 2
60 *PUSHA Push AX,CX,DX,BX,original SP,BP,SI,DI
9C PUSHF Set [SP-2] to flags register, then decrement SP by 2
D0 /2 RCL eb,1 Rotate 9-bit quantity (CF, EA byte) left once
D2 /2 RCL eb,CL Rotate 9-bit quantity (CF, EA byte) left CL times
C0 /2 ib *RCL eb,ib Rotate 9-bit quantity (CF, EA byte) left ib times
D1 /2 RCL ew,1 Rotate 17-bit quantity (CF, EA word) left once
D3 /2 RCL ew,CL Rotate 17-bit quantity (CF, EA word) left CL times
C1 /2 ib *RCL ew,ib Rotate 17-bit quantity (CF, EA word) left ib times
D0 /3 RCR eb,1 Rotate 9-bit quantity (CF, EA byte) right once
D2 /3 RCR eb,CL Rotate 9-bit quantity (CF, EA byte) right CL times
C0 /3 ib *RCR eb,ib Rotate 9-bit quantity (CF, EA byte) right ib times
D1 /3 RCR ew,1 Rotate 17-bit quantity (CF, EA word) right once
D3 /3 RCR ew,CL Rotate 17-bit quantity (CF, EA word) right CL times
C1 /3 ib *RCR ew,ib Rotate 17-bit quantity (CF, EA word) right ib times
F3 REP (prefix) Repeat following MOVS,LODS,STOS,INS, or OUTS CX times
65 #REPC (prefix) Repeat following CMPS or SCAS CX times or until CF=0
F3 REPE (prefix) Repeat following CMPS or SCAS CX times or until ZF=0
64 #REPNC (prfix) Repeat following CMPS or SCAS CX times or until CF=1
F2 REPNE (prfix) Repeat following CMPS or SCAS CX times or until ZF=1
F2 REPNZ (prfix) Repeat following CMPS or SCAS CX times or until ZF=1
F3 REPZ (prefix) Repeat following CMPS or SCAS CX times or until ZF=0
CB RETF Return to far caller (pop offset, then seg)
C3 RET Return to near caller (pop offset only)
CA iw RETF iw RET (far), pop offset, seg, iw bytes
C2 iw RET iw RET (near), pop offset, iw bytes pushed before Call
D0 /0 ROL eb,1 Rotate 8-bit EA byte left once
D2 /0 ROL eb,CL Rotate 8-bit EA byte left CL times
C0 /0 ib *ROL eb,ib Rotate 8-bit EA byte left ib times
D1 /0 ROL ew,1 Rotate 16-bit EA word left once
D3 /0 ROL ew,CL Rotate 16-bit EA word left CL times
C1 /0 ib *ROL ew,ib Rotate 16-bit EA word left ib times
0F 28/0 #ROL4 eb Rotate nibbles: Heb=Leb HAL,Leb=LAL LAL=Heb
D0 /1 ROR eb,1 Rotate 8-bit EA byte right once
D2 /1 ROR eb,CL Rotate 8-bit EA byte right CL times
C0 /1 ib *ROR eb,ib Rotate 8-bit EA byte right ib times
D1 /1 ROR ew,1 Rotate 16-bit EA word right once
D3 /1 ROR ew,CL Rotate 16-bit EA word right CL times
C1 /1 ib *ROR ew,ib Rotate 16-bit EA word right ib times
0F 2A/0 #ROR4 eb Rotate nibbles: Leb=Heb Heb=LAL AL=eb
9E SAHF Store AH into flags SF ZF xx AF xx PF xx CF
D0 /4 SAL eb,1 Multiply EA byte by 2, once
D2 /4 SAL eb,CL Multiply EA byte by 2, CL times
C0 /4 ib *SAL eb,ib Multiply EA byte by 2, ib times
D1 /4 SAL ew,1 Multiply EA word by 2, once
D3 /4 SAL ew,CL Multiply EA word by 2, CL times
C1 /4 ib *SAL ew,ib Multiply EA word by 2, ib times
D0 /7 SAR eb,1 Signed divide EA byte by 2, once
D2 /7 SAR eb,CL Signed divide EA byte by 2, CL times
C0 /7 ib *SAR eb,ib Signed divide EA byte by 2, ib times
D1 /7 SAR ew,1 Signed divide EA word by 2, once
D3 /7 SAR ew,CL Signed divide EA word by 2, CL times
C1 /7 ib *SAR ew,ib Signed divide EA word by 2, ib times
1C ib SBB AL,ib Subtract with borrow immediate byte from AL
1D iw SBB AX,iw Subtract with borrow immediate word from AX
80 /3 ib SBB eb,ib Subtract with borrow immediate byte from EA byte
18 /r SBB eb,rb Subtract with borrow byte register from EA byte
83 /3 ib SBB ew,ib Subtract with borrow immediate byte from EA word
81 /3 iw SBB ew,iw Subtract with borrow immediate word from EA word
19 /r SBB ew,rw Subtract with borrow word register from EA word
1A /r SBB rb,eb Subtract with borrow EA byte from byte register
1B /r SBB rw,ew Subtract with borrow EA word from word register
AE SCAS mb Compare bytes AL - ES:[DI], advance DI
AF SCAS mw Compare words AL - ES:[DI], advance DI
AE SCASB Compare bytes AX - ES:[DI], advance DI
AF SCASW Compare words AX - ES:[DI], advance DI
0F 14/0 #SETBIT eb,CL Set bit CL of eb
0F 15/0 #SETBIT ew,CL Set bit CL of ew
0F 1C/0 ib #SETBIT eb,ib Set bit ib of eb
0F 1D/0 ib #SETBIT ew,ib Set bit ib of ew
0F 01 /0 *SGDT m Store 6-byte Global Descriptor Table register to M
D0 /4 SHL eb,1 Multiply EA byte by 2, once
D2 /4 SHL eb,CL Multiply EA byte by 2, CL times
C0 /4 ib *SHL eb,ib Multiply EA byte by 2, ib times
D1 /4 SHL ew,1 Multiply EA word by 2, once
D3 /4 SHL ew,CL Multiply EA word by 2, CL times
C1 /4 ib *SHL ew,ib Multiply EA word by 2, ib times
D0 /5 SHR eb,1 Unsigned divide EA byte by 2, once
D2 /5 SHR eb,CL Unsigned divide EA byte by 2, CL times
C0 /5 ib *SHR eb,ib Unsigned divide EA byte by 2, ib times
D1 /5 SHR ew,1 Unsigned divide EA word by 2, once
D3 /5 SHR ew,CL Unsigned divide EA word by 2, CL times
C1 /5 ib *SHR ew,ib Unsigned divide EA word by 2, ib times
0F 01 /1 *SIDT m Store 6-byte Interrupt Descriptor Table register to M
0F 00 /0 *SLDT ew Store Local Descriptor Table register to EA word
0F 01 /4 *SMSW ew Store Machine Status Word to EA word
F9 STC Set carry flag
FD STD Set direction flag so SI and DI will decrement
FB STI Set interrupt enable flag, interrupts enabled
0F 31/r #STOBITS rb,rb Store AX to ES:DI,bit rb (incr. DI,rb), rb+1 bits
0F 39/0 ib #STOBITS rb,ib Store AX to ES:DI,bit rb (incr. DI,rb), ib+1 bits
AA STOS mb Store AL to byte [DI], advance DI
AB STOS mw Store AX to word [DI], advance DI
AA STOSB Store AL to byte ES:[DI], advance DI
AB STOSW Store AX to word ES:[DI], advance DI
0F 00 /1 *STR ew Store Task Register to EA word
2C ib SUB AL,ib Subtract immediate byte from AL
2D iw SUB AX,iw Subtract immediate word from AX
80 /5 ib SUB eb,ib Subtract immediate byte from EA byte
28 /r SUB eb,rb Subtract byte register from EA byte
83 /5 ib SUB ew,ib Subtract immediate byte from EA word
81 /5 iw SUB ew,iw Subtract immediate word from EA word
29 /r SUB ew,rw Subtract word register from EA word
2A /r SUB rb,eb Subtract EA byte from byte register
2B /r SUB rw,ew Subtract EA word from word register
0F 22 #SUB4S Sub CL nibbles BCD at DS:SI from ES:DI (CL even,NZ)
A8 ib TEST AL,ib AND immediate byte into AL for flags only
A9 iw TEST AX,iw AND immediate word into AX for flags only
F6 /0 ib TEST eb,ib AND immediate byte into EA byte for flags only
84 /r TEST eb,rb AND byte register into EA byte for flags only
F7 /0 iw TEST ew,iw AND immediate word into EA word for flags only
85 /r TEST ew,rw AND word register into EA word for flags only
84 /r TEST rb,eb AND EA byte into byte register for flags only
85 /r TEST rw,ew AND EA word into word register for flags only
0F 10/0 #TESTBIT eb,CL Test bit CL of eb, set Z flag
0F 11/0 #TESTBIT ew,CL Test bit CL of ew, set Z flag
0F 18/0 ib #TESTBIT eb,ib Test bit ib of eb, set Z flag
0F 19/0 ib #TESTBIT ew,ib Test bit ib of ew, set Z flag
9B WAIT Wait until BUSY pin is inactive (HIGH)
0F 00 /4 *VERR ew Set ZF=1 if segment can be read, selector ew
0F 00 /5 *VERW ew Set ZF=1 if segment can be written to, selector ew
9r XCHG AX,rw Exchange word register with AX
86 /r XCHG eb,rb Exchange byte register with EA byte
87 /r XCHG ew,rw Exchange word register with EA word
86 /r XCHG rb,eb Exchange EA byte with byte register
9r XCHG rw,AX Exchange with word register
87 /r XCHG rw,ew Exchange EA word with word register
D7 XLAT mb Set AL to memory byte [BX + unsigned AL]
D7 XLATB Set AL to memory byte DS:[BX + unsigned AL]
34 ib XOR AL,ib Exclusive-OR immediate byte into AL
35 iw XOR AX,iw Exclusive-OR immediate word into AX
80 /6 ib XOR eb,ib Exclusive-OR immediate byte into EA byte
30 /r XOR eb,rb Exclusive-OR byte register into EA byte
83 /6 ib XOR ew,ib Exclusive-OR immediate byte into EA word
81 /6 iw XOR ew,iw Exclusive-OR immediate word into EA word
31 /r XOR ew,rw Exclusive-OR word register into EA word
32 /r XOR rb,eb Exclusive-OR EA byte into byte register
33 /r XOR rw,ew Exclusive-OR EA word into word register
* Starred forms will not execute on 8086/8088! See note at top of chart.
# These instructions work only on NEC chips! See note at top of chart.