Abstract


Control SignalPurposeValue
RegDstSelect the destination register, either rd or rt0 for rt

1 for rd
RegWriteEnable the writing back to the register file0, nothing happens

1, WD get written to WR
ALUSrcSelect the 2nd operand for the ALU, either from the register file or the immediate value from the Instruction0 for MIPS R-Type Instruction rt

1 for MIPS I-Type Instruction, but 0 for ALU
ALUcontrolSelect the operation to be performed by the ALU4bits, see MIPS ALU for more information
MemRead/MemWriteEnable reading/writing of data memory, both can’t be enabled at the same time0 is disable

1 is enable
MemToRegSelect the result to be written back to the Register, either result from the MIPS Data Memory or ALU1 for read data from data memory

0 for read data from ALU
PCSrcSelect the next value for the Register0 for PC + 4

1 for PC + 4 + 4 * immed

Important

The MemToReg Multiplexer is the only one with its inputs swapped.