Diode (P)ROM wasn't built in a day

A project log for YGREC8

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

Yann Guidon / YGDESYann Guidon / YGDES 08/27/2019 at 21:520 Comments

As I build the instruction assembler and disassember, I must also provide a way to store instructions. This was already covered in #YGREC16 - YG's 16bits Relay Electric Computer in the log PROM boards.

Things have evolved since 2017 and I now have a whole bunch of DIP switches (Log: I hope that's enough this time) and pretty large proto boards... I have just what is required to build boards with 16×4=64 instructions :-)

But let's look at how these boards must be organised. The YGREC8 has 16-bits instructions so a higher density than the 24 bits of the YGREC16. And there are only 256 addressable instructions. That's 256×2=512 DIP switches, I have more than 700 in stock these days :-)

Then the topology must be optimised to reduce the number of relays : how many lines and columns ?

So be it : the PROM cards are organised with 4 columns.

I'll try to build a 8×4 board to get started... because I also need to build the 2 big MUXes for lines and colums. Where are my boxes of SMD diodes ? :-D