Arithmetic and Logic Unit in Detail
You should have heard of an Arithmetic and Logic Unit before, while discussing a Computer CPU or a micro controller. In this tutorial we will look at what an ALU really is?
We will discuss a 4 bit ALU; this would limit many possibilities 16. We would assume that associated registers and instruction set are also 4 bit.
We will discuss a 4 bit ALU; this would limit many possibilities 16. We would assume that associated registers and instruction set are also 4 bit.
The basic Unit: 1 bit ALU
We assume you are familiar with logic gates, and also have come across a 1 bit adder. It simple adds two 1 bit inputs as shown below.
| Inputs | Outputs | ||
|---|---|---|---|
| A | B | S | C |
| 0 | 0 | 0 | 0 |
| 1 | 0 | 1 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 1 | 0 | 1 |