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Logical Group Instructions (Part-III) - XRA and XRI

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XRA R: 
  • This instruction logically EX-OR the contents of the specified register with the contents of the accumulator.
  • Register R can be any 8-bit general purpose register like A, B, C, D, E, H and L.
  • The result is stored in the accumulator.
  • S (Sign flag), Z (Zero flag), P (Parity flag) are modified.
  • CY (Carry flag) and AC (Auxiliary Carry flag) are reset.
  • It is a one byte instruction.
  • Register addressing mode is used.
Example:
If A = 1010 1011 = ABH and D = 0001 0010 = 12H
XRA D ; This instruction will logically EX-OR the contents of A (ABH) with the contents of D (12H) and the result (B9H) is stored in A.

XRA M:

  • This instruction logically EX-OR the contents of the memory location pointed by HL register pair with the contents of the accumulator.
  • The result is stored in the accumulator.
  • S (Sign flag), Z (Zero flag), P (Parity flag) are modified.
  • CY (Carry flag) and AC (Auxiliary Carry flag) are reset.
  • It is a one byte instruction.
  • Register indirect addressing mode is used.
Example:
If HL = 2000H, (2000H) = 0100 0110 = 46H and A = 0011 0000 = 30H
XRA M ; This instruction will logically EX-OR the contents of A (30H) with the contents of location 2000H i.e. 46H and the result (76H) is stored in A.

XRI 8-bit data:
  • This instruction logically EX-OR the 8-bit data given in the instruction itself with the contents of the accumulator.
  • The result is stored in the accumulator.
  • S (Sign flag), Z (Zero flag), P (Parity flag) are modified.
  • CY (Carry flag) and AC (Auxiliary Carry flag) are reset.
  • It is a two byte instruction.
  • Immediate addressing mode is used.
Example:
If A = 1010 1100 = ACH
XRI 2CH ; This instruction will logically EX-OR the contents of A (ACH) with 2CH and the result (10H) is stored in A.

NOTE: XOR instruction is used to invert or complement some bits of a binary number.

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