Table B-2. 8051 Instruction Set
Description
Instr.
Cycles
Hex
Code
Mnemonic
Byte
Data Transfer
MOV A, Rn
Move register to A
1
2
1
2
1
2
2
2
2
3
2
3
1
2
2
3
1
1
1
1
1
1
2
2
1
2
1
E8-EF
E5
MOV A, direct
MOV A, @Ri
Move direct byte to A
2
Move data memory to A
1
E6-E7
74
MOV A, #data
MOV Rn, A
Move immediate to A
2
Move A to register
1
F8-FF
A8-AF
78-7F
F5
MOV Rn, direct
MOV Rn, #data
MOV direct, A
MOV direct, Rn
MOV direct, direct
MOV direct, @Ri
MOV direct, #data
MOV @Ri, A
Move direct byte to register
Move immediate to register
Move A to direct byte
2
2
2
Move register to direct byte
Move direct byte to direct byte
Move data memory to direct byte
Move immediate to direct byte
MOV A to data memory
2
88-8F
85
3
2
86-87
75
3
1
2
F6-F7
A6-A7
76-77
90
MOV @Ri, direct
MOV @Ri, #data
MOV DPTR, #data
Move direct byte to data memory
Move immediate to data memory
Move immediate to data pointer
2
3
MOVC A, @A+DPTR Move code byte relative DPTR to A
3
93
MOVC A, @A+PC
MOVX A, @Ri
MOVX A, @DPTR
MOVX @Ri, A
MOVX @DPTR, A
PUSH direct
Move code byte relative PC to A
Move external data (A8) to A
Move external data (A16) to A
Move A to external data (A8)
Move A to external data (A16)
Push direct byte onto stack
Pop direct byte from stack
Exchange A and register
3
83
2-9*
2-9*
2-9*
2-9*
2
E2-E3
E0
F2-F3
F0
C0
POP direct
2
D0
XCH A, Rn
1
C8-CF
C5
XCH A, direct
Exchange A and direct byte
2
EZ-USB v1.9
Appendix B: 8051 Architectural Overview
B - 7
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