In the context of the 8085 microprocessor instruction set, specifically under logical instructions, CMA stands for Complement the Accumulator. This instruction inverts each bit within the Accumulator.
Understanding CMA
The CMA instruction flips each bit of the Accumulator. This means that all 0s become 1s, and all 1s become 0s. It essentially calculates the one's complement of the value stored in the Accumulator.
Example
Let's say the Accumulator contains the binary value 01010101. After executing the CMA instruction, the Accumulator will contain 10101010.
Purpose
The CMA instruction is useful for various logical operations and calculations, particularly when dealing with negative numbers or performing bitwise inversions.
Details of CMA Instruction (8085)
- Mnemonic: CMA
- Description: Complements the contents of the Accumulator.
- Operation: The contents of the Accumulator are replaced by their one's complement.
- Addressing Mode: Implicit.
- Flags Affected: No flags are affected by this instruction.
- Instruction Length: 1 byte
- Machine Cycles: 1 (T states: 4)
Summary
CMA, or "Complement the Accumulator," is a fundamental instruction in the 8085 microprocessor that performs a bitwise inversion on the contents of the Accumulator. It is a single-byte instruction that doesn't affect any flags.
