Multiplexers
Three 2x1 and one 4x1 multiplexers are used in the design. Depending on the select signal, the multiplexer will output the corresponding value.
| Type of MUX | Inputs from | Select signal | Output to | |
|---|---|---|---|---|
| Selecting the address source for PC register | 2x1 MUX | PC+4,Address computer by the ALU | PC_SELECT control signal | PC register |
| Selecting the operand 1 for the ALU | 2x1 MUX | DATA1 from register file, PC value | OP1_SEL | DATA1 input ofthe ALU |
| Selecting the operand 2 for the ALU | 2x1 MUX | DATA2 from register file, PC value | OP2_SEL | DATA1 input ofthe ALU |
| Selecting the operand 1 for the ALU | 2x1 MUX | DATA1 from register file, PC value | OP1_SEL | DATA2 input ofthe ALU |
| Selecting the writeback source | 4x1 MUX | ALU result, PC + 4 value, Immediate value, Read data from data memory | WB_SEL | Write data input of the register file |