How to design a processor

Advice: Keep it simple

The most reliable part is the part that is not in the design !

Instruction set
Microarchitecture
Control unit
Microprogramming
Tools
Reading

This page aims to promote "how to" in processor design. Promoting the National IC Design Contest (hosted by National Electronics and Computer Technology of Thailand) for the digital design part.

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

S1 microprogramming

Tools

Assembler     a3 (for CPU3)    as2 (for S2)
Simulator     CPU3    S1 (see tools section)     S2
Microprogramming     S1 microprogram (see tools section)
S2 processor tools

Reading

My papers on intruction set design

extended virtual machine: Chongstitvatana, P., "Post processing optimization of byte-code instructions by extension of its virtual machine", 20th Electrical Engineering Conference, Thailand, 1997. (pdf)
comparing register and stack: Wongsiriprasert, C. and Chongstitvatana, P., "Performance comparison between two virtual machine interpreters : stack-based vs. register-based", Proc. of 3rd Annual National Symposium on Computational Science and Engineering, Bangkok, 1999, pp. 401-406. (pdf)
instruction compression: Chongstitvatana, P. and Kotrajaras, V., "Instruction compression by nibble coding: war on the old front", IEEE Thailand section: Silver Jubilee Symposium, 15 Nov 2002. ( pdf )
instruction set design: Chongstitvatana, P. "The Art of Instruction Set Design", Invited paper in Proc. of Electrical Engineering Conference, Thailand, 2003. ( pdf )
futuristic architecture: hardware multiplexing: Piromsopa, K., Bavonparadon, P. and Chongstitvatana, P., "Hardware multiplexing: towards a resource efficient reconfigurable processor", 3rd International Symposium on Communications and Information Technologies, 3-5 September 2003, Thailand. ( pdf )

last update 9 Oct 2003
P. Chongstitvatana