TommyPROM/docs/_docs/design-300-pcb.md
2024-04-13 15:52:26 -04:00

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---
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)