In terms of transistors I think MCPU by Tim Boscke can be hard to beat - https://github.com/cpldcpu/MCPU https://github.com/cpldcpu/MCPU , however how many tran

In terms of transistors I think MCPU by Tim Boscke can be hard to beat - https://github.com/cpldcpu/MCPU https://github.com/cpldcpu/MCPU , however how many transistors this 8 bit CPU has is not clear.