DCX

 Syntax: DCX Rhp

Where Rhp is the higher order register of the pair BC or DE or HL.

Byte: 1byte

Addressing Mode: Register Addressing

Working: 

1. 

2. 

3. 

4. Flag

Example: 

1. DCX H

Where [HL]= 1000H....[H]= 10, [L]= 00

After execution of DCX H

 [HL]= 0FFF H

2. DCX B

Where [ BC] = 1055 H

After execution of DCX B

[ BC]= 1054 H