DIY 1702a Programmer

I've resumed working on the PAiA 8700 computer. It uses some very old, and hard to program EPROMs: 1702As. They require +37V, +47V, +59V and ground to program.

I've come up with a relatively easy to build DIY programmer. It doesn't require a parallel port, or dozens of transistors. It's Arduino based, and uses mostly common parts.
Here's what it looks like:


And here's a schematic:


A boost converter daughter board is used to generate a high voltage, over 60V. It then gets regulated down to the various voltages needed. IC1 (TL783) has to be calibrated to +47V, then the other voltages will fall into place.
An Arduino nano is able to manipulate the high voltages through three ULN2003 transistor arrays, and one IRF520 MOSFET.

Right now the code is very crude, but functional. It's on pastebin here. The binary for the 1702A is included in the Arduino program. On power up/reset the programming sequence begins. It's finished when the pin 13 led stops flashing.

I've now added the Eagle CAD files to my github here.

PAiA 8700 Schematic Redraw

The PAiA 8700 computer is an optional part for the PAiA 4700 modular system. It gives you the ability to run software like a "pink music" generator.

I took interest in it because it combines my favorite CPU, the 6502 (6503 here), and analog synthesis. It's pretty hard to find one these days, but PAiA published the schematics and they're still available. I needed them in Eagle CAD format to be able to work on them, so I redrew them here. In the process, I like to think I've improved the clarity and layout of the schematic.
The board is as close a reproduction as I could manage.

I've also typed out the original assembly source file and assembled binary.

Files available on my github




Also, a memory map. Why not?


I was able to find some NOS and begin assembling a brand new 8700 reproduction. More to come.