B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 DA DB DC DD DE DF E0 E1 E2 E3 E4 E5 E6 E7
A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 @DPTR, A addr11 @R0, A @R1, A A direct, A @R0, A @R1, A R0, A R1, A R2, A R3, A R4, A R5, A R6, A R7, A
2 2 1 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 1 1 2 1 1 1 1 1 1 1 1 1 1 2 2 2 1 1 3 1 1 2 2 2 2 2 2 2 2 1 2 1 1 1 2 1 1
ACALL CPL CPL CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE CJNE PUSH AJMP CLR CLR SWAP XCH XCH XCH XCH XCH XCH XCH XCH XCH XCH XCH POP ACALL SETB SETB DA DJNZ XCHD XCHD DJNZ DJNZ DJNZ DJNZ DJNZ DJNZ DJNZ DJNZ MOVX AJMP MOVX MOVX CLR MOV MOV MOV
A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 offset addr11 C, bit @A+DPTR A, #immed direct, #immed @R0, #immed @R1, #immed R0, #immed R1, #immed R2, #immed R3, #immed R4, #immed R5, #immed R6, #immed R7, #immed
E8 E9 EA EB EC ED EE EF F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 FA FB FC FD FE FF
1 1 1 1 1 1 1 1 1 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1
MOV MOV MOV MOV MOV MOV MOV MOV MOVX ACALL MOVX MOVX CPL MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV
2 1 1 2 2 1 1 1 1 1 1 1 1 1 1 2 2 2 3 2 2 1 1 1 1 1 1 1 1 1 1 2 2 2 3 2 2 1 1 1 1 1 1 1 1 1 1 2 2 2 3 2 2 1 1
ACALL RETI RLC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC ADDC JC AJMP ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL ORL JNC ACALL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL ANL JZ AJMP XRL XRL XRL XRL XRL XRL

31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F 60 61 62 63 64 65 66 67
68 69 6A 6B 6C 6D 6E 6F 70 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F
1 1 1 1 1 1 1 1 2 2 2 1 2 3 2 2 2 2 2 2 2 2 2 2
XRL XRL XRL XRL XRL XRL XRL XRL JNZ ACALL ORL JMP MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV MOV
addr11 A A, #immed A, direct A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 offset addr11 direct, A direct, #immed A, #immed A, direct A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 offset addr11 direct, A direct, #immed A, #immed A, direct A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 offset addr11 direct, A direct, #immed A, #immed A, direct A, @R0 A, @R1
addr11 bit C A, #immed, offset A, direct, offset @R0, #immed, offset @R1, #immed, offset R0, #immed, offset R1, #immed, offset R2, #immed, offset R3, #immed, offset R4, #immed, offset R5, #immed, offset R6, #immed, offset R7, #immed, offset direct addr11 bit C A A, direct A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 direct addr11 bit C A direct, offset A, @R0 A, @R1 R0, offset R1, offset R2, offset R3, offset R4, offset R5, offset R6, offset R7, offset A, @DPTR addr11 A, @R0 A, @R1 A A, direct A, @R0 A, @R1
Opcodes
The following table lists the 8051 instructions by HEX code. Hex Bytes Mnemonic Code 0 1 NOP 1 2 AJMP 2 3 LJMP 3 1 RR 4 1 INC 5 2 INC 6 1 INC 7 1 INC 8 1 INC 9 1 INC 0A 1 INC 0B 1 INC 0C 1 INC 0D 1 INC 0E 1 INC 0F 1 INC 10 3 JBC 11 2 ACALL 12 3 LCALL 13 1 RRC 14 1 DEC 15 2 DEC 16 1 DEC 17 1 DEC 18 1 DEC 19 1 DEC 1A 1 DEC 1B 1 DEC 1C 1 DEC 1D 1 DEC 1E 1 DEC 1F 1 DEC 20 3 JB 21 2 AJMP 22 1 RET 23 1 RL 24 2 ADD 25 2 ADD 26 1 ADD 27 1 ADD 28 1 ADD 29 1 ADD 2A 1 ADD 2B 1 ADD 2C 1 ADD 2D 1 ADD 2E 1 ADD 2F 1 ADD 30 3 JNB Operands addr11 addr16 A A direct @R0 @R1 R0 R1 R2 R3 R4 R5 R6 R7 bit, offset addr11 addr16 A A direct @R0 @R1 R0 R1 R2 R3 R4 R5 R6 R7 bit, offset addr11 A A, #immed A, direct A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 bit, offset Hex Bytes Mnemonic Code 80 2 SJMP 81 2 AJMP 82 2 ANL 83 1 MOVC 84 1 DIV 85 3 MOV 86 2 MOV 87 2 MOV 88 2 MOV 89 2 MOV 8A 2 MOV 8B 2 MOV 8C 2 MOV 8D 2 MOV 8E 2 MOV 8F 2 MOV 90 3 MOV 91 2 ACALL 92 2 MOV 93 1 MOVC 94 2 SUBB 95 2 SUBB 96 1 SUBB 97 1 SUBB 98 1 SUBB 99 1 SUBB 9A 1 SUBB 9B 1 SUBB 9C 1 SUBB 9D 1 SUBB 9E 1 SUBB 9F 1 SUBB A0 2 ORL A1 2 AJMP A2 2 MOV A3 1 INC A4 1 MUL A5 reserved A6 2 MOV A7 2 MOV A8 2 MOV A9 2 MOV AA 2 MOV AB 2 MOV AC 2 MOV AD 2 MOV AE 2 MOV AF 2 MOV B0 2 ANL Operands offset addr11 C, bit A, @A+PC AB direct, direct direct, @R0 direct, @R1 direct, R0 direct, R1 direct, R2 direct, R3 direct, R4 direct, R5 direct, R6 direct, R7 DPTR, #immed addr11 bit, C A, @A+DPTR A, #immed A, direct A, @R0 A, @R1 A, R0 A, R1 A, R2 A, R3 A, R4 A, R5 A, R6 A, R7 C, /bit addr11 C, bit DPTR AB @R0, direct @R1, direct R0, direct R1, direct R2, direct R3, direct R4, direct R5, direct R6, direct R7, direct C, /bit