8051 XCH Instruction

Exchange Accumulator with byte variable

Instruction	XCH A,byte
Function	Exchange Accumulator with byte variable
Description	XCH loads the Accumulator with the contents of the indicated variable, at the same time writing the original Accumulator contents to the indicated variable. The source/destination operand can use register, direct, or register-indirect addressing.
Example	R0 contains the address 20H. The Accumulator holds the value 3FH (0011111lB). Internal RAM location 20H holds the value 75H (01110101B). The following instruction, XCH A,@R0 leaves RAM location 20H holding the values 3FH ( 00111111B) and 75H (01110101B) in the accumulator.
Variants	XCH A, Rn XCH A, direct address XCH A,@Ri

Instruction	XCH A, Rn
Bytes	1
Cycles	1
Encoding	1 1 0 0 1 n n n
Operation	A swap Rn
Flags Affected	C AC F0 RS1 RS0 OV P
Example	XCH A, R6
Bytes: Number of bytes required to encode the instruction. Cycles: Number of instruction cycles required to execute the instruction. Note that there are 12 oscillator cycles to one instruction cycle on a standard 8051. Encoding: Lists the byte encoding for the instruction. Operation: Lists, step-by-step, the operations performed by the instruction. Flags Affected: are highlighted in Bold

Instruction	XCH A, direct address
Bytes	2
Cycles	1
Encoding	1 1 0 0 0 1 0 1 A7...A0
Operation	A swap (direct)
Flags Affected	C AC F0 RS1 RS0 OV P
Example	XCH A, 45h
Bytes: Number of bytes required to encode the instruction. Cycles: Number of instruction cycles required to execute the instruction. Note that there are 12 oscillator cycles to one instruction cycle on a standard 8051. Encoding: Lists the byte encoding for the instruction. Operation: Lists, step-by-step, the operations performed by the instruction. Flags Affected: are highlighted in Bold

Instruction	XCH A,@Ri
Bytes	1
Cycles	1
Encoding	1 1 0 0 0 1 1 i
Operation	A swap (Ri)
Flags Affected	C AC F0 RS1 RS0 OV P
Example	XCH A, @R0
Bytes: Number of bytes required to encode the instruction. Cycles: Number of instruction cycles required to execute the instruction. Note that there are 12 oscillator cycles to one instruction cycle on a standard 8051. Encoding: Lists the byte encoding for the instruction. Operation: Lists, step-by-step, the operations performed by the instruction. Flags Affected: are highlighted in Bold

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Related topics:
8051 Data Transfer Instructions   |   8051 MOV Instruction   |   8051 MOVC Instruction   |   8051 MOVX Instruction   |   8051 PUSH Instruction   |   8051 POP Instruction   |   8051 XCHD Instruction

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List of topics: 8051

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