Multi-cycle datapath: control signals

What else is needed?  Branches and jumps

Possible sources for PC value:

Fig. 5.33

(PC + 4) directly from ALU

ALUout: result of branch calculation

Result of concatenation of left-shifted 26 bits with upper 4 bits of PC (jump)

Note that the PC is updated both unconditionally and conditionally,

so 2 control signals are needed

PCWriteCond: ANDed with ALU Zero to control PC update for branch

This result is ORed with PCWrite

PCSource: controls MUX to select input to PC

0: ALU result

1: ALUOut

2: Jump address

Why do we need both 0 and 1 inputs?

Control signals are listed in Fig. 5.34