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Arithmetic Logic Unit (ALU) Notes

Last Updated on 2021-10-20 by Clay

Arithmetic Logic Unit (ALU) is an electronic component that performs arithmetic and bit operations on binary integers.

An ALU component has 3 Buses:

  • Operation Integer A
  • Operation Integer B
  • Operation Result Y

These values are all binary integer signals, and the bus widths of A, B and Y are also the same.

The Opcode is to pass the operand to be executed.

The status of ALU is divided into input and output.

  • Input: Status input allows ALU component to receive other information, such as the carry information from the last ALU.
  • Output: Output the ALU operation result.
    • Carry-out: "carry" of addition, "borrow" of subtraction, and overflow
    • Zero: Indicates that all bits of the operation result are logic zero
    • Negative: The result of the operation is negative
    • Overflow: The result of the operation overflows and exceeds the value range of Y
    • Parity: Indicates the parity check result of the output number Y, indicating the parity of the number of logical 1s in Y

The above introduction is refer to https://en.wikipedia.org/wiki/Arithmetic_logic_unit


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