XCHG

Syntax:  XCHG Rhp

Where Rhp is higher order register  the pair. ( BC or DE)

Byte: 1byte

Addressing Mode: Register Addressing

Working: for execution of this instruction, microprocessor will allocate first byte for opcode and the operand is register which don't need allocation.

After execution of this instruction content of register pair given as operand will get swapped with content of HL register pair.

Example: XCHG B

where [C]= 50H & [B] = 20 H,

[H]= 80H & [L]= 60H

(i.e. BC = 2050H and HL = 8060H)

After execution of  XCHG B

[H]= 20 H   &    [L]= 50H

[B]= 80H  &   [C]= 60H

Program: Write ALP  to swap content of BC with DE where [DE] = 4455H and

 [BC] = 1122H. 

Solution: Assume HL = 0000H

Start:  XCHG B    ;BC= 0000H & HL = 1122H

           XCHG D ; HL= 4455H& DE= 1122H

           XCHG B ; HL = 0000H & BC = 4455H

           HLT

Output: [DE] = 1122H and [BC]= 4455H