Megaprocessor
I hadn't realised people would be so interested ! I'll try and answer some of the questions that have been asked.<p>I just use a single type of MOSFET, the 2N7000.
I did look at BJTs (in fact the whole thing started because I wanted to teach myself about "proper" transistors) but working out what resistor values to use to cope with varying fanouts/ins etc was too scary for me. One of the fundamental drivers when making design choices was that I really really want it to work when its built, it'll be heartbreaking if/when it doesn't, so I try to favour robustness.<p>The single MOSFET is also, I'm currently guessing, the cause of the slow speed. If you look at how the professionals (chip makers) do gates they tend to have two versions of the logic, one driving the positive case and the other driving the negative using both P and N MOSFETS. So the output is actively driven either way. My circuits only actively drive in one direction and rely on a pullup resistor (the 10ks) to generate a 1 output. Halves the number of transistors I need, but cripples the speed. I need to do some experiments to prove/disprove that.<p>I am planning on putting the design files on the website.<p>And I'm in Cambridge UK as opposed to Cambridge MA.