Compare with Register
The contents of the register are compared with the contents of the accumulator here register may be any one of the A, B, C, D E, H, or L registers. The instruction format is
CMPR (A-R)
Actually the comparison is done by subtracting the contents of the register from the contents of the accumulator. The contents of the register and the accumulator do not change the flags are modified similar to subtraction.
Flags : All flags are modified as they would change in subtract operation. But the contents of both the operand do not change.
Although all flags are modified but the conclusion can be made only by CY and Z flag as shown below
If A> R : CY and Z flags are reset.
IF A= R: Z Flag is set and CY flag is reset.
IF A < R : CY is set and Z flag s reset.