(C) Copyright 1993, 1994 By Harald Feldmann Revision 04, Nov 3rd 1994.
Mnemonic: AAA
Bug in : Different implementation in 88 and 86 versus 286+
Function:
Mnemonic: AAD
Bug in : Is an opcode variant on Intel's 88,86,286,386,486
Function:
Mnemonic: AAM
Bug in : Is an opcode variant on Intel's 88,86,286,386,486
Function:
Mnemonic: AAS
Bug in : Intel's documentation
Function:
Mnemonic: ADD4S
Bug in : Rarely documented, except in NEC manuals
Function:
Mnemonic: BOUND reg,mem
Bug in : NEC V20 handles it differently from Intel 286+. But apparently,
Function:
Mnemonic: N/A
Bug in : some 386, some 486
Function:
Mnemonic: BRKEM imm
Bug in : Rarely documented, except in NEC manuals
Function:
Mnemonic: BSF op1,op2
Bug in : Intel's documentation
Function:
Mnemonic: BSWAP reg32
Bug in : 486
Function:
Mnemonic: BT
Bug in : No bug, avoid use on ports in 386, 486
Function:
Mnemonic: BTC op1,op2
Bug in : No bug, avoid use on ports in 386, 486
Function:
Mnemonic: BTR op1,op2
Bug in : No bug, avoid use on ports in 386, 486
Function:
Mnemonic: BTS
Bug in : No bug, avoid use on ports in 386, 486
Function:
Mnemonic: CLEAR1 reg/mem,CL/immediate
Bug in : Rarely documented, except in NEC manuals
Function:
See Also: NECINS, EXT, TEST1, NOT1, SET1
Mnemonic: CMP4S
Bug in : Rarely documented, except in NEC manuals
Function:
ES:DI, but does not store the result. The length of the string, in BCD
See Also: ADD4S, SUB4S, ROL4, ROR4
Mnemonic: CMPS
Bug in : Early 286 in protected mode
Function:
Mnemonic: CMPXCHG
Bug in : pre-B step 486
Function:
Mnemonic: CPUID
Bug in : Is undocumented for 486, seems not to work on tested AMD 486s
Function:
Input: EAX = 0000 0000 : Check CPU 486+ installed
Output: after CPUID:
Input: EAX = 0000 0001 : Obtain model specific information
Output: after CPUID:
Note: the Mode Flag is supported only on the NEC V20/30,
Mnemonic: EXT reg8,reg8 / EXT reg8,imm4
Bug in : Rarely documented, except in NEC manuals
Function:
zero. DS:SI specify the first memory location to read, and the low 4-bits
See Also: NECINS, TEST1, NOT1, CLEAR1, SET1
Mnemonic: FPO2 fp-op / FPO2 fp-op,mem
Bug in : Rarely documented, except in NEC manuals
Function:
Mnemonic: HLT
Bug in : No bug, handy use of instruction described below
Function:
Mnemonic: IBTS op1,op2
Bug in : 386, 486 conflicting instruction opcode.
Function:
Mnemonic: IMUL op
Opcode : F6w [mod:101:r/m] disp
Function:
Mnemonic: INS, INSB, INSW, INSD
Bug in : early 286, some 386, early 486, NEC conflicting mnemonic: INS
Function:
Mnemonic: INS reg8,reg8 / INS reg8,imm4
Bug in : Rarely documented, except in NEC manuals
Function:
See Also: EXT, TEST1, NOT1, CLEAR1, SET1
Mnemonic: INVD
Bug in : some 486
Function:
here:
Mnemonic: JMP dest
Bug in : A to C0 step of 486
Function:
Mnemonic: LAR reg1,reg/mem
Bug in : some 386
Function:
Mnemonic: LOADALL
Bug in : Is an undocumented opcode on 286,some 386,some early 486 ?
Function:
Mnemonic: LSL reg1,reg/mem
Bug : some 386
Function:
Mnemonic: MOV involving CRx, DRx or TRx, MOV to SS, CS
Bug in : some 88,some 86,some 386,all 386,A to C0 step of 486
Function:
fetcher:
label:
Mnemonic: MOVSB / MOVSW / MOVSD
Bug in : early 286 in PM, some 386
Function:
Example:
Mnemonic: MUL reg
Bug in : 386
Function:
EAX: 'A':'B' EAX: 'A':'B'
EDX: 'E':'F' EDX: 'E':'F'
Mnemonic: NOT1 reg/mem,CL/immediate
Bug in : Rarely documented, except in NEC manuals
Function:
See Also: NECINS, EXT, TEST1, CLEAR1, SET1
Mnemonic: POP
Bug in : POP CS is a valid opcode for 88, 86, invalid opcode for 186
Function:
Mnemonic: POPA / POPAD
Bug in : some 386
Function:
Legend:
Mnemonic: PUSH reg / PUSH mem
Bug in : PUSH (E)SP different operation on 286+, PUSH mem on some 286 in PM
Function:
(or SS:ESP on 386+), after which (E)SP is decremented by a word or dword.
Mnemonic: RDTSC
Bug in : Poorly documented for Pentium Processor
Function:
Mnemonic: REPC / REPNC
Bug in : Rarely documented except in NEC manuals, invalid on Intel CPUs
Function:
Mnemonic: ROL4 reg8/mem8
Bug in : Rarely documented, except in NEC manuals
Function:
See Also: ADD4S, SUB4S, CMP4S, ROR4
Mnemonic: ROR4 reg8/mem8
Bug in : Rarely documented, except in NEC manuals
Function:
See Also: ADD4S, SUB4S, CMP4S, ROL4
Mnemonic: SET1 reg/mem,CL/immediate
Bug in : Rarely documented, except in NEC manuals
Function:
See Also: NECINS, EXT, TEST1, NOT1, CLEAR1
Mnemonic: SETALC
Bug in : Is an undocumented opcode on 88,86,286,386,486
Function:
Mnemonic: SHL, SAL, SHR, SAR, ROL, RCL, ROR, RCR, and all xxxD variants
Bug in : 186+ will AND the shift- or rotate count with 1f before execution
Function:
Mnemonic: SUB4S
Bug in : Rarely documented, except in NEC manuals, is conflicting opcode
Function:
ES:DI. The length of the string, in BCD digits, is specified in CL. Unlike
See Also: ADD4S, CMP4S, ROL4, ROR4
Mnemonic: TEST1 reg/mem,CL/immediate
Bug in : Rarely documented, except in NEC manuals, opcodes 0f 10 and
Function:
See Also: NECINS, EXT, NOT1, CLEAR1, SET1
Mnemonic: UNKNOWN
Bug in : Is an unknown opcode on 286
Function:
Mnemonic: VERR op / VERW op
Bug in : some 386
Function:
Mnemonic: WBINVD
Bug in : some 486
Function:
here:
Mnemonic: WRMSR / RDMSR
Bug in : Are minimally documented opcodes for Pentium+ compatible CPUs
Function:
A: supports the CPUID instruction and
Mnemonic: N/A
Bug in : some 486 / 487
Function:
Note: lesser precision does not significantly reduce execution time.
Mnemonic: FSBP0, FSBP1, FSBP2, FSBP3
Bug in : Are IIT 2c87+ instructions
Function:
Mnemonic: FSIN / FCOS
Bug in : Undocumented instructions on IIT 2c87 math chips
Function:
Mnemonic: FDIV / FDIVP
Bug in : some 486
Function:
Mnemonic: FDIVR / FDIVRP
Bug in : some 486
Function:
Mnemonic: FLDENV
Bug in : some 387
Function:
Mnemonic: FMUL4X4 or F4X4
Bug in : Is an IIT special instruction
Function:
Mnemonic: FENI / FNENI / FDISI / FNDISI
Bug in : Opcodes have no meaning on 287+ (are ignored there)
Function:
Mnemonic: FPREM
Bug in : all 87 and 287
Function:
Mnemonic: FPTAN
Bug in : some 486 / 487, difference between pre-287xls and 287xl+
Function:
Mnemonic: FRSTOR
Bug in : some 387
Function:
Mnemonic: FSAVE / FNSAVE
Bug in : some 387, some 386
Function:
Mnemonic: FSETPM
Bug in : no bug, it only works on 287 and 287xl. ignored on 386+
Function:
Mnemonic: FRSTPM
Bug in : no bug, it only works on 287 and 287xl. ignored on 386+
Function:
Mnemonic: FSCALE
Bug in : some 486
Function:
Mnemonic: FSINCOS
Bug in : some 486, invalid on pre-287xl and IIT
Function:
Mnemonic: FSTENV
Bug in : some 386
Function: