Logical Instructions
These instructions perform logical operations on data
stored in registers, memory and status flags.
The logical operations are:
AND
OR
XOR
Rotate
Compare
Complement
2
AND, OR, XOR
Any 8-bit data, or the contents of register, or
memory location can logically have
AND operation
OR operation
XOR operation
with the contents of accumulator.
The result is stored in accumulator.
3
Rotat
e
Each bit in the accumulator
or right to the next position.
can be shifted either left
4
Compare
Any 8-bit data, or the contents of register, or
memory location can be compares for:
Equality
Greater Than
Less Than
with the contents of accumulator.
The result is reflected in status
flags. 5
Complement
The contents of accumulator can be
complemented.
Each 0 is replaced by 1 and each 1 is replaced by 0.
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Logical Instructions
Opcode Operand Description
CMP R Compare register or memory
M with accumulator
The contents of the operand (register or memory)
are compared with the contents of the accumulator.
Both contents are preserved .
The result of the comparison is shown by setting the
flags of the PSW as follows:
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Logical Instructions
Opcode Operand Description
CMP R Compare register or memory
M with accumulator
if (A) < (reg/mem): carry flag is set
if (A) = (reg/mem): zero flag is set
if (A) > (reg/mem): carry and zero flags are
reset.
Example: CMP B or CMP M
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Logical Instructions
Opcode Operand Description
CPI 8-bit data Compare immediate with accumulator
The 8-bit data is compared with the contents of
accumulator.
The values being compared remain
unchanged.
The result of the comparison is shown by setting the
flags of the PSW as follows:
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Logical Instructions
Opcode Operand Description
CPI 8-bit data Compare immediate with accumulator
if (A) < data: carry flag is set
if (A) = data: zero flag is set
if (A) > data: carry and zero flags are
reset
Example: CPI 89H
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Logical Instructions
Opcode Operand Description
ANA R Logical AND register or memory
M with accumulator
The contents of the accumulator are logically ANDed with the
contents
of register or memory.
The result is placed in the accumulator.
If the operand is a memory location, its address is specified by the
contents of H-L pair.
S, Z, P are modified to reflect the result of the operation.
CY is reset and AC is set.
Example: ANA B or ANA M.
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Logical Instructions
Opcode Operand Description
ANI 8-bit data Logical AND immediate with accumulator
The contents of the accumulator are logically ANDed with
the 8-bit data.
The result is placed in the accumulator.
S, Z, P are modified to reflect the result.
CY is reset, AC is set.
Example: ANI
86H.
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Logical Instructions
Opcode Operand Description
ORA R Logical OR register or memory
M with accumulator
The contents of the accumulator are logically ORed with the contents of the register or
memory.
The result is placed in the accumulator.
If the operand is a memory location, its address is specified by the contents of H-L
pair.
S, Z, P are modified to reflect the result.
CY and AC are reset.
Example: ORA B or ORA M.
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Logical Instructions
Opcode Operand Description
ORI 8-bit data Logical OR immediate with accumulator
The contents of the accumulator are logically ORed with
the 8-bit data.
The result is placed in the accumulator.
S, Z, P are modified to reflect the result.
CY and AC are reset.
Example: ORI
86H.
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Logical Instructions
Opcode Operand Description
XRA R Logical XOR register or memory
M with accumulator
The contents of the accumulator are XORed with the contents
of
the register or memory.
The result is placed in the accumulator.
If the operand is a memory location, its address is specified by
the contents of H-L pair.
S, Z, P are modified to reflect the result of the operation.
CY and AC are reset.
Example: XRA B or XRA
M.
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Logical Instructions
Opcode Operand Description
XRI 8-bit data XOR immediate with accumulator
The contents of the accumulator are XORed with the
8-bit data.
The result is placed in the accumulator.
S, Z, P are modified to reflect the result.
CY and AC are reset.
Example: XRI
86H.
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Logical Instructions
Opcode Operand Description
RLC None Rotate accumulator left
Each binary bit of the accumulator is rotated left by
one position.
Bit D7 is placed in the position of D0 as well as in the
Carry flag.
CY is modified according to bit D7.
S, Z, P, AC are not affected.
Example:
RLC.
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Logical Instructions
Opcode Operand Description
RRC None Rotate accumulator right
Each binary bit of the accumulator is rotated right by
one position.
Bit D0 is placed in the position of D7 as well as in the
Carry flag.
CY is modified according to bit D0.
S, Z, P, AC are not affected.
Example:
RRC.
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Logical Instructions
Opcode Operand Description
RAL None Rotate accumulator left through carry
Each binary bit of the accumulator is rotated left by
one position through the Carry flag.
Bit D7 is placed in the Carry flag, and the Carry flag is
placed in the least significant position D0.
CY is modified according to bit D7.
S, Z, P, AC are not affected.
Example: RAL.
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Logical Instructions
Opcode Operand Description
RAR None Rotate accumulator right through carry
Each binary bit of the accumulator is rotated right by
one position through the Carry flag.
Bit D0 is placed in the Carry flag, and the Carry flag is
placed in the most significant position D7.
CY is modified according to bit D0.
S, Z, P, AC are not affected.
Example: RAR.
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Logical Instructions
Opcode Operand Description
CMA None Complement accumulator
The contents of the accumulator are
complemented.
No flags are affected.
Example: CMA.
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Logical Instructions
Opcode Operand Description
CMC None Complement carry
The Carry flag is complemented.
No other flags are affected.
Example: CMC.
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Logical Instructions
Opcode Operand Description
STC None Set carry
The Carry flag is set to 1.
No other flags are affected.
Example: STC.
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