Tuesday, May 14, 2019

Backplane "Mapper" (DG Nova, DCC D-116 & Entrex 480/Nixdorf 620)

This is a crazy project that I'm just muddling my way through with sheer ignorance and determination.

I want to test every connection in every slot of the backplane of Dominique's Entrex 480/Nixdorf 620, since it is the only known surviving system of its kind in existence, and then reverse engineer the thing from the center outward.

So, here's the backplane "adapter board" design (version 2)
Click to download the Gerber files version 3 by Alberto Medrano

Order this at 1.2mm thickness, NOT 1.6mm default.  I did my first round at 1.6mm default, and the board was too thick to fit into the backplane card edge connectors.

And here's my concept schematic on how I'm going to use an Arduino (I know...can't I do better??!!!) to test each and every connection in each slot I plug the set into.

Yes, there are so many things wrong with it...I know...

Here's the Gerber files of my latest version by Alberto Medrano

And for the first time, I'm going to try to order these from JLCPBC

This is what I'm comparing against, and these are the only backplane schematics/charts that I have for any Entrex 480/Nixdorf620, DSS-116 or Data General NOVA system.  Can anyone else find more on bitsavers, or elsewhere?

Wednesday, May 8, 2019

Digital Computer Controls - D-116 16-Bit Computer Handbook - 1972

Well, since the Entrex 480 / Nixdorf 620 system clearly has a D-116 as it's processor, it seems that acquiring this manual was a priority...so we did!

Vintage Digital Computer controls - D-116 16-Bit Computer Handbook - 1972

For comparison, Dominique's Nixdorf 620 processor label