1 ECE243 CPU Modification Lab

2 You will add new insts to a CPU A CPU that implements mini ISA exists –you can compile it, load it onto DE2, run programs Your job: add support for new instructions –just like examples we did “on paper” in class –but harder cuz you have to do it for real Kewlness factor: –a taste of real processor design

3 Outline of What to Do 1) download/read documents/tutorials!! 2) decide steps (cycles) for each new inst 3) decide additions to datapath (and draw them) 4) decide new control states –and what ctrl signals (outputs) will be 5) implement your design You should already know how to do (1)-(4) The challenge is learning how to do (5)

4 5) Implementing Your Design modify the control first: modify verilog file 'FSM.v' –add any new control signals to the list of outputs –make the state register wider if out of bits for new states –add new state transitions (easy) –add list of control signal values for each new state modify the datapath--two different ways to do it: –modify verilog file (change code in 'multicycle.v') –OR modify schematic (mouse/GUI)

5 Programming Your New CPU You must write new mini-ISA programs –to exercise the new insts you added to the CPU You have to modify the mini-ISA assembler –to support these new insts

6 Don’t Panic! Lots of info to read –lab web page, tutorials Several new tools to learn –very basic verilog –Quartus/schematic –mini-ISA assembler Not too bad if you carefully follow the documentation