--- title: "Introducing Bit Preserve" description: "PDF schematics are great, blut tough to work with. Bit Preserve is a project to capture vintage electronics (computers and video game) schematics in KiCad" canonical: "https://www.baldengineer.com/bit-preserve-vintage-schematics-with-kicad.html" author: "James Lewis" date: "2019-06-12T18:13:01Z" lastmod: "2022-03-31T04:00:15Z" image: "https://www.baldengineer.com/wp-content/uploads/2019/06/Bit-Preserve-Banner-1980px.jpg" categories: ["blog","golden-delicious","kicad","projects"] tags: ["6052","8-bit","bitpreserve","kicad","retro"] --- # Introducing Bit Preserve A project I work on in my spare time is creating a portable Apple II. Like many of my projects, one leads into another. I started out wanting to make a mobile Apple II, and now I'm working on a project called [Bit Preserve](https://github.com/baldengineer/bit-preserve). How did I get from one project to the next? Well, as I looked into how to make a portable Apple II, I realized a significant issue. The original Apple II logic board has almost 80 ICs. Being a design from 1975, they are all through-hole packages. The good news is that except for the ROM chips, they are all off-the-shelf components. But such a size means it might be impossible to turn it into something handheld. I almost abandoned the project. Then, I learned about a chip included in the Apple IIgs. The name of the [ASIC is "MEGA II."](/drawing-apple-mega-ii-breakout-in-kicad.html) (Nothing to do with Arduino.) It is a chip that integrates all of those off-the-shelf chips into an 84 pin package. As I dove deeper into the project, I realized I needed other support chips to make the MEGA II useful. There is a decent book that discusses the technical details of the Apple IIgs, but it does not get into chip or board level design. For that detail, I had to look at the original schematics. While I am ecstatic that someone archived these original documents as PDFs, I quickly became frustrated. Sometimes the scan quality is not very good, and it is nearly impossible to search for symbols across multiple pages. I thought to myself, "There has got to be a better way!" [Bit Preserve on GitHub](https://github.com/baldengineer/bit-preserve) ## What is in the Bit Preserve repository? Instead of relying on these bitmapped documents, I decided to re-create the entire Apple IIgs schematic in KiCad. Why KiCad? Long story short, I settled on KiCad because it is an open source tool and has an accessible file format. Those two qualities make it ideal for preserving a schematic long term. For fun, I started [streaming my efforts on Twitch](https://www.twitch.tv/collections/E2xxU4QlnhW9HQ?filter=collections). What surprised me is that people started contacting me about other computer schematics. A friend and colleague emailed me a ten-megabyte zip file with Commodore 64 schematics he collected over time. So. I created a [GitHub repository called "Bit Preserve."](https://github.com/baldengineer/bit-preserve) The goal is to re-create schematic for vintage electronics using KiCad. Today there are two systems available Bit Preserve. The first is the [Apple IIgs schematic](https://github.com/baldengineer/bit-preserve/tree/master/Apple/Apple%20II/IIgs/ROM3%20Schematic) I am working on. And the second is a pull request I received from an [Altair 8800](https://github.com/baldengineer/bit-preserve/tree/master/MITS/Altair%208800) enthusiast. You'll see other directories, but they only contain readme files. When possible, I am providing links to the original schematics. I have decided that this repository will not store the PDF versions of the original schematics. If you know of schematics for other systems, feel free to send a pull request with an update to the readme files. ### How can you help? If there is an old computer or video game system you think should be preserved, start capturing its schematic! Even if you are not a vintage computer enthusiast, you can still contribute to the project. Think of this as an opportunity to learn how to use KiCad. As my Twitch stream shows, I am learning new things about KiCad myself. Like, how and when to use [labels and busses](https://www.twitch.tv/videos/337704932?collection=E2xxU4QlnhW9HQ)? Or, how to [push and shove lines](https://www.twitch.tv/videos/437395128?collection=E2xxU4QlnhW9HQ) in the schematic. ## Learn More For background on the project, I did a talk at KiCon 2019 called "Preserving History with KiCad." In that talk, I briefly describe my portable Apple II project and get into why I decided to start Bit Preserve. You can also [download the slides here](/slides/preserving-history-with-kicad-kicon-2019). [YouTube video fBaU4JZOVzk](https://www.youtube.com/watch?v=fBaU4JZOVzk) Let me know if you want to help or about other what systems to include.