One of the essential digital logic components of CPUs is the Arithmetic Logic Unit (ALU). It usually performs
- addition
- subtraction
- multiplication
- division as some of the logic and arithmetic operations.
To design an Arithmetic Logic Unit (ALU). It usually performs logical and arithmetic operations. VHDL is used to design and implement an ALU.
- A is forced to 8 Bit input (A is set to = 0000001)
- B is forced to 8 Bit input (A is set to = 0000010)
- alu_sel is forced to choose the arithematic operation
- alu_result will be the output
| Operation | Input A | Input B | Output |
|---|---|---|---|
| Addition | 0000001 | 0000010 | 00000011 |
| Subraction | 0000001 | 0000010 | 11111111 |
| Multiplication | 0000001 | 0000010 | 00000010 |
| Division | 0000001 | 0000010 | 00000000 |
| Logical shift left | 0000001 | 0000010 | 00000010 |
| Logical shift right | 0000001 | 0000010 | 00000000 |
| Rotate left | 0000001 | 0000010 | 00000010 |
| Rotate right | 0000001 | 0000010 | 10000000 |
| AND | 0000001 | 0000010 | 00000000 |
| OR | 0000001 | 0000010 | 00000000 |
| XOR | 0000001 | 0000010 | 00000011 |
| NOR | 0000001 | 0000010 | 11111100 |
| NAND | 0000001 | 0000010 | 11111111 |
| XNOR | 0000001 | 0000010 | 11111100 |
| XNOR | 0000001 | 0000010 | 11111100 |
| A>B | 0000001 | 0000010 | 00000000 |
| A<B | 0000001 | 0000010 | 11111111 |
| A=B | 0000001 | 0000010 | 00000000 |
