Instruction type XCHG in 8085 Microprocessor

Microprocessor8085

In 8085 Instruction set, there is one mnemonic XCHG, which stands for eXCHanGe. This is an instruction to exchange contents of HL register pair with DE register pair. This instruction uses implied addressing mode. As it is1-Byte instruction, so It occupies only 1-Byte in the memory. After execution of this instruction, the content between H and D registers and L and E registers will get swapped respectively.

Mnemonics, Operand Opcode(in HEX) Bytes
XCHG EB 1

Let us suppose, HL and DE register pairs are having ABCDH and 6789H contents respectively. After execution of instruction XCHG the contents of HL and DS register pairs will be 6789H and ABCDH respectively. Here is the content training table for the better understanding.

Before After
(HL) ABCDH 6789H
(DE) 6789H ABCDH

Address Hex Codes Mnemonic Comment
2006 EB XCHG Swapping the contents of DE and HL register pairs

Let us see the timing diagram of this instruction XCHG as below −

XCHG

Summary − So this instruction XCHG requires 1-Byte, 4-Machine Cycles (Opcode Fetch) and 4 T-States for execution as shown in the timing diagram.

raja
Published on 30-Nov-2018 16:42:38
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