This project presents the design and implementation of an 8-bit Arithmetic Logic Unit using 74LS283 4-bit binary adders and 74LS86 XOR gates. The ALU performs addition and subtraction on two 8-bit binary numbers, selected through DIP switches, and displays results via LEDs. Subtraction is implemented using the two’s complement method, where the B input is inverted through XOR gates and a carry in is introduced.
- 74LS283 – Two 4-bit full adders (to build 8-bit adder/subtractor).
- 74LS86 – XOR gates (to invert B input during subtraction).
- DIP Switches – User inputs for binary values.
- LEDs – Result output display.
- Addition Mode:
Result = A + B - Subtraction Mode:
Result = A + (~B) + 1
- 8-bit ALU Schematic
Date: 21/09/2025