Instruction type CMC in 8085 Microprocessor

In 8085 Instruction set, CMC stands for “CoMplement the Carry flag”. It performs complement operation on the cy flag, and the result is stored back in the cy flag.

Mnemonics, Operand Opcode(in HEX) Bytes
CMC 3F 1

The result of execution of this instruction has been depicted in the following tracing table −

Before After


1 0

Address Hex Codes Mnemonic Comment
2001 3F CMC Complement of Cy when Cy=1

The timing diagram against this instruction CMC execution is as follows −


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

karthikeya Boyini
karthikeya Boyini

I love programming (: That's all I know