A Diode (P)ROM was (almost) built in a day

A project log for YGREC8

A byte-wide stripped-down version of the YGREC16 architecture

Yann Guidon / YGDESYann Guidon / YGDES 09/03/2019 at 12:350 Comments

So I tried to build a prototype and it was almost finished in a day :-)

32 instructions, 64 DIP-switches with 16 pins each, that's already 1024 soldering joints.

Then 512 diodes (LL4148), linked in 8 rows, make another kilojoints :

but it's not as hard as it sounds.

What is still missing is the 64 column wires and the connectors. I'll also add one LED per line.

Of course a dedicated PCB would ease assembly but this

  1. would be very costly
  2. I have more important other expenses
  3. I already have these parts in stock
  4. I don't want to waste money with a flawed PCB design that a prototype could solve.

Anyway with 32 instructions I'll have enough room to test interesting things and it's not as hard as it looks.

I want to make the board design modular, each board can be relocated physically on a backplane to change the address. There are 2 decoders, large MUXes for the lines and columns, that will not need changes, while the data boards can be of any type (DIP switches, solder joints or anything else I come up with).