@8ff2c4ef Ha, I also just checked that the enables are grounded 🙂. The schematics seem to indicate that the MSB output bit 7 only gives a signal "SN" (https://github.com/warmech/lisa-hardware/blob/main/CPU%20Card/Schematics/Video.pdf), so I assume this is only used to generate the "magical" Lisa serial number – there are three different versions of the PROM on bitsavers (SN_*.BIN at http://bitsavers.informatik.uni-stuttgart.de/bits/Apple/Lisa/firmware/). 

 @8ff2c4ef Untested – I don't know if the enables for the registered outputs work the way I think (the 6309 also has enables that should tristate the outputs when not active) and I hope I didn't make any typos when transcribing the logic terms – but this source assembles using GALasm and fits a 22V10. Note that I had to swap the Q2 and Q3 output pins.

https://github.com/michaelengel/lisaprom/blob/main/GAL22V10/GAL22V10_Lisa.pld 

 @c76776cc @40275da3 Whow, that's neat 👍. And the printers are not even that expensive. 

 @c76776cc @40275da3 Of course, just wanted to point out the things I noticed 🙂. On the original logos, the letters are only printed onto the surface. I guess that producing the logo as double-shot plastics (similar to higher end keycaps for mechanical keyboards) is pretty much impossible or would have been too expensive even for NeXT... It will be interesting to see what this looks like when 3D printed. 

 @c76776cc @40275da3 That looks pretty good already, whow!

Three small things I noticed:

– the height of your 3D logo is about twice the height of the original
– the letters of the original seem to leave a bit more space to the corners of the "cube" surface they are printed on
– the color for the "T" looks a bit different on my logos here (but this could be due to aging) – the precise colors for print and screen can be found at http://www.nextcomputers.org/NeXTfiles/Docs/ColorReference.jpg