8051 LOGICAL INSTRUCTIONS

Logical Type Instruction

 

ANL Instruction

ANL Performs bit wise AND operation between the specified byte.

When used to modify an output port, the value used as the port data will be read from the output data latch, not the input pins of the port.

format example Opcode/Encoding Flags affected
ANL A, #data ANL A, #3FH
01010100
(54H)
immediate
P
ANL A, @Ri ANL A, @R0 0101011i (57H) P
ANL A, direct ANL A, 4BH
01010101
(55H)
direct
P
ANL A, Rn ANL A, R4 01011nnn (nnn is Rn) P
ANL C, /bit ANL C, /22H
10110000
(B0H)
bit
None
ANL C, bit ANL C,22H
10000010
(82H)
bit
C
ANL direct, #data ANL 30H, #77H
01010011
(53H)
direct immediate
None

SETB Instruction

  • SETB instruction sets the bit operand to a value of 1
  • Can be used to carry flag or any other directly addressable bit
  • No other flags are affected by this instruction.
Format Example/ Operation Opcode/ Encoding Next Opcode Byte Flags affected Byte
SETB bit SETB 63h 11010010 63h C 2
SETB C SETB C

C=1

11010011 C 1

 CPL Instruction

CPL instruction is used to logically complement the value of the specified operand

Example: MOV A, #55h ;                                   A= 01010101

CPL A                  ; Answer will be     A= 10101010 

format Example/

Operation

Opcode/ Encoding Flags affected Byte Cycles
CPL Acc CPL A

A= NOT A

11110100 None 1 1
CPL bit CPL 55h

(bit)= NOT (bit)

10110010 bit
None 2 1
CPL carry CPL C

C= NOT C

10110011 C 1 1

 

CLR Instruction

CLR instruction clears the bit to a value of 0.

Example : MOV A, #34h                           A=00110100

CLR A                           ; will set A=00

Format Example

Operation

Opcode/Encoding Flags affected Byte Cycles
CLR Acc CLR A

A=0

11100100 P 1 1
CLR bit CLR 01h

(bit)=0

11000010 bit
none 2 1
CLR Carry CLR C

C=0

11000011 C 1 1

 

ORL Instruction

ORL instruction performs a bitwise logical OR operation on the specified operands

When used to modify an output port, the value used as the port data will be read from the output data latch, not the input pins of the port.

           
Format example Opcode/ Encoding Flags affected Byte Cycles
ORL A, #data ORL A,#01h

A=A OR #data

01000100, #immediate P 2 1
ORL A, @Ri ORL A, @R0

A=A OR (Ri)

0100011i P 1 1
ORL A, direct ORL A, direct

ORL A, P0

01000101 P 2 1
ORL A, Rn ORL A, R5

A=A or R5

01001nnn P 1 1
ORL C, /bit ORL C, /22h

C=C or (NOT bit)

10100000 C 2 2
ORL C, bit ORL C, 22h

C=C or Bit

01110010 C 2 2
ORL direct, #data ORL P0, #01h

(direct)= (direct) OR #data

01000011, direct, #immediate none 3 2
ORL direct, A ORL P0, A

(direct)= (ditrect) OR A

01000010, direct none 2 1

XRL Instruction

XRL instruction performs a logical exclusive OR operation between the specified operands

When used to modify an output port, the value used as the port data is read from the output data latch, not the pins of the port.

Format Example/ Operation Opcode/Encoding Flags affected Byte Cycles
XRL A, #immd XRL A, #0FFh

A=A XOR #immd

01100100 P 2 1
XRL A, @Ri XRL A, @R0

A=A XOR (Ri)

0110011i P 1 1
XRL A, direct XRL A, 34h

A=A XOR (direct)

01100101, 8-bit direct addr P 2 1
XRL A, Rn XRL A, R7

A=A XOR Rn

01101nnn P 1 1
XRL direct, #immd XRL 34h, #0FFh

(direct)=(direct) XOR #immd

01100011 none 3 2
XRL direct, A XRL 34h, A

(direct) =(direct) XOR A

01100010 none 2 1
Updated: August 3, 2019 — 6:06 pm

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