Datapath: R-type

1. Fetch instruction and increment PC

Fig. 5.21

2. Obtain operands from register file, based on source register numbers

3. Perform ALU operation, using ALU control to select, ALUSrc = 0

4. Select output from ALU using MemtoReg = 0

5. Write back to destination register (RegWrite = 1, RegDst = 1 for $rd)

Note that this entire path is combinational, but the values are generated in the order shown.