The arithmetic logic unit (ALU) part of a CPU is usually capable of performing various arithmetic, bitwise, and comparison operations on binary numbers. In our simple breadboard CPU, the ALU is just able to add and subtract. It’s connected to the A and B registers and outputs either the sum of A+B or the difference of A-B.

## Videos

- Learn how computers add numbers and build a 4 bit adder circuit
- Twos complement: Negative numbers in binary
- ALU Design
- Building the ALU
- Troubleshooting the ALU
- Testing the computer’s ALU

## Schematic

(coming soon!)

## Parts list

Quantity | Description |
---|---|

1 | Breadboard |

2 | 74LS86 (Quad XOR gate) |

1 | 74LS245 (Octal bus transceiver) |

2 | 74LS283 (4-bit binary full adder) |

8 | Red LED |