How to design a processor

Advice: Keep it simple
The most reliable part is the part that is not in the design !

Design an instruction set
Design a microarchitecture
  Draw functional blocks 
  Write microsteps
Write a simulator
Write an assembler
Implement the microarchitecture
Implement the control unit
Test and Debug (the most time consuming task)

Try to design a "minimum" instruction set, the set that covers the intended applications.  The number of instruction effects the complexity of the design and the testing, especially the testing.  

Instruction Set
  Examples 
  8-bit  Z80 Z8 6809 2650  AVR
  16-bit S1 PDP-11 CompactRISC (ref)  32016 
  32-bit 32032 S2 ARM
  My collection  CPU3  FRIDAY 
  
Microarchitecture
  S1 FRIDAY  

Control unit
  hardwired
  microprogrammed

Microprogramming

Tools
  Assembler
  Simulator
  Microprogramming

last update 9 Oct 2003
P. Chongstitvatana