Arithmetic and Logic Unit

Tasks:

1. Design ALU components for basic arithmetic and logical operations.

2. Simulate the design using a Simulation Tool.

3. Test ALU for different bit widths (e.g., 4-bit, 8-bit, 16-bit) and various operations.

ALU

An Arithmetic Logic Unit (ALU) is a fundamental component of a computer's central processing unit (CPU). It performs arithmetic operations like addition, subtraction, multiplication, and division, as well as logical operations such as AND, OR, XOR, and NOT. The ALU serves as the computational powerhouse of the processor, processing binary data and executing instructions that are critical for running programs. Its efficiency and design directly impact a computer's overall performance.

4-bit ALU

From the diagram:

The Opcode is a 3-bit input (labeled as S0S1S2).
This 3-bit select line can represent 8 possible combinations (000 to 111).
Each combination corresponds to one of the functional circuits (e.g., ADD, AND, OR, etc.).

Here's a breakdown of the operations based on typical ALU design conventions and the given diagram :

Opcode

Operation Selected

000

Addition (A + B)

001

Subtraction (A - B)

010

Multiplication (A x B)

011

Divider (A / B)

100

Bitwise AND (A AND B)

101

Bitwise OR(A OR B)

110

Bitwise NAND (A NAND B)

111

Bitwise EXOR (A XOR B)

How Selection Works:

The Opcode is decoded and sent to the multiplexer.
The multiplexer chooses one of the inputs (outputs from various operation circuits) to pass to the OUTPUT BITS.

ALU Circuit designed, implemented, and simulated in the laboratory to perform arithmetic and logical operations, demonstrating input (A, B), Opcode control, and output functionality.

8-bit ALU

Learning Outcome:

Understand ALU Functions
- Learn the basic operations an ALU performs, like addition, subtraction, bitwise AND/OR, and shifts.
Designing the ALU
- Design an ALU that supports N-bit operations, ensuring it can handle multiple input sizes.
Implementing Arithmetic Operations
- Implement addition and subtraction algorithms using techniques like binary addition and two’s complement for subtraction.
Bitwise Operations
- Understand and implement bitwise AND/OR operations and their role in logical computations.
Shift Operations
- Learn how to implement logical and arithmetic shifts (left and right) for N-bit inputs.
Control Signals and Multiplexers
- Use control signals to select which operation (addition, subtraction, AND/OR, shifts) the ALU performs.
- Implement multiplexers to switch between different operations.
Testing and Debugging
- Simulate and test the ALU’s functionality to ensure correct behavior for each operation and troubleshoot errors.

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