Abstract
| Control Signal | Purpose | Value |
|---|---|---|
RegDst | Select the destination register, either rd or rt | 0 for rt1 for rd |
RegWrite | Enable the writing back to the register file | 0, nothing happens1, WD get written to WR |
ALUSrc | Select the 2nd operand for the ALU, either from the register file or the immediate value from the Instruction | 0 for MIPS R-Type Instruction rt1 for MIPS I-Type Instruction, but 0 for ALU |
ALUcontrol | Select the operation to be performed by the ALU | 4bits, see MIPS ALU for more information |
MemRead/MemWrite | Enable reading/writing of data memory, both can’t be enabled at the same time | 0 is disable1 is enable |
MemToReg | Select the result to be written back to the Register, either result from the MIPS Data Memory or ALU | 1 for read data from data memory0 for read data from ALU |
PCSrc | Select the next value for the Register | 0 for PC + 41 for PC + 4 + 4 * immed |
Important
The
MemToRegMultiplexer is the only one with its inputs swapped.