MIPS Processor Control, control signals

Where are the control signals?

Types of control signals

Control SignalExecution StagePurpose
MIPS RegDstDecode / Operand fetchSelect the destination register number
MIPS RegWriteDecode / Operand fetch / Result WriteEnable writing of MIPS register file
MIPS ALUSrcALUSelect 2nd operand for MIPS Arithmetic-logical unit (ALU) / EX Stage
MIPS ALUControlALUSelect the operation to be performed
MIPS MemRead / MemWriteMemoryEnable READ/WRITE of MIPS data memory
MIPS MemToRegResult WriteSelect the result to be written back to MIPS register file
MIPS PCSrcMemory / Result WriteSelect the next PC value. How does MIPS handle the program counter (PC)?

Generating control signals

Control signals are generated based on instruction to be executed:

Idea

Implementation

Key Idea

Go through each unique set of MIPS opcode , MIPS function code , see what MIPS control signal are generated.

Details

Construct and observe the truth table generated.

Design using logic gates.