Question

Explain the following instruction of 8085 Micro-processor:

RAR (Consider cy = 0)

Answer 1

RAR: [ROTATE ACCUMULATOR RIGHT THROUGH CARRY]

Format: [A_n] ← [A_n+1], [A₇] ← [Cy], [Cy] ← [A₀]

Addressing: Implied addressing

Group: Logical group

Bytes: 1 byte

Flag: Cy

Comment: The contents of the accumulator are rotated one bit to the right through the carry flag. Since CY = 0 is assumed initially, the carry flag value (0) is moved to bit A7 of the accumulator, and bit A0 of the accumulator is transferred to the carry flag. Only the carry flag is affected.

The function of RAR is shown in the following figure.

Thus [A] = 1D H
         [Cy] = 0