TTL logic? I see 10K and 470 ohm resistors in the pix, or the color codes are messed up by the camera, and 5V supplies and not a diode in sight and the layout

TTL logic? I see 10K and 470 ohm resistors in the pix, or the color codes are messed up by the camera, and 5V supplies and not a diode in sight and the layout doesn't look RTL to me. This makes the project interesting because "most" retro builders do DTL. So that's cool. Takes a thundering lot more transistors (admittedly no diodes) and the noise budget and fanout aren't as easy but it'll work... I suppose from a parts minimization standpoint you could use the inherent diode in a bipolar transistor to build DTL using only transistors. AFAIK (and I've studied this for awhile) no one has built anything substantial at the transistor level using CMOS architecture. Virtually everyone does DTL, there's plenty of relay based work, this guy is the only discrete TTL family I'm aware of, and I've seen a little RTL logic family out there. That would be interesting. I always thought the totem output stage of a TTL gate would be "too hard" compared to the other logic families so I got to hand it to this guy, impressive. A better "vital statistics" comparison would be the DTL logic straight-8 original DEC PDP8 which would vaguely fit on a desk and used about 1500 transistors, 10K or so diodes. It looks like this: http://www.pdp8.net/straight8/functional_restore.shtml http://www.pdp8.net/straight8/functional_restore.shtml In my infinite spare time I'm going to build a straight-8 using all SMD components (so my cards will be half business card sized rather than half a sheet of paper sized). I'm sure I'll get to that right about 2080 or so at this rate. The advantage of cloning an existing architecture is vast piles of software ready to use. The disadvantage of using modern high beta, high Ft transistors instead of 60s era transistors is I'm likely to build some great VHF/UHF oscillators instead of logic gates. OP seems to have gotten past this problem, or hasn't run into it yet. WRT moving parts and "make it like a book" comments, the last thing you want with 50K or so wire jumpers is movement, even if every bend only breaks 0.01% of wires per "fold" that going to multiply up into pain if you swing 10K wires open and closed 1K times. Ribbon cable and standard connectors could help.