---
title: Printed Circuit Boards
permalink: /docs/pcb
exerpt: "Printed Circuit Boards"
---

Although TommyPROM was originally designed as a one-off programmer to be used on a breadboard, there are now some PCB versions.  The original TommyPROM PCB for 28C256 chips is described here, and the [TommyPROM32 PCB](tommyprom32-pcb), for handling a variety of chips, has its own page.

[![TommyPROM PCB](images/TommyPROM-pcb-500.jpg)](images/TommyPROM-pcb.jpg)[![TommyPROM PCB](images/TommyPROM32-SST39SF-500.jpg)](images/TommyPROM32-SST39SF.jpg)


## 28C256 PCB

A PCB version for the 28C256 and 28C64 chips was built to support a SAP-1 TTL breadboard
computer.  This project required a lot of burns for its  microcode and the PCB version
with the ZIF socket was much quicker than prying the chips out of a breadboard without
disturbing any of the wires.

The [KiCad design files](https://github.com/TomNisbet/TommyPROM/tree/master/schematics)
are in the project repo.

[![TommyPROM PCB](images/TommyPROM-pcb-with-microcode-500.jpg)](images/TommyPROM-pcb-with-microcode.jpg)

[![TommyPROM schematic](images/TommyPROM-nano-sch.png)](images/TommyPROM-nano-sch.png)