Classic Repair Toolbox (or CRT hence forward) is a utility tool for repairing and diagnosing vintage computers and peripherals.
The project is a direct spin-off from an older project, Commodore Repair Toolbox which now resides in a faint and distant memory only. The new Classic project (compared to Commodore) was realized as a complete rewrite, to be able to support Linux and macOS natively, but also to be able to support more hardware and not focus primarily on Commodore (Amstrad, Spectrum?).
With CRT you can easily view technical schematics, zoom, identify components, view chip pinouts, do manual circuit tracing, study datasheets, view oscilloscope images, ressources and various other information, helping you diagnosing and repairing old vintage hardware.
It is (for now) primarily dedicated to Commodore, and have several built-in profiles for Commodore computers and it has a single Amstrad computer also, but it can support any kind of hardware, as you can add your own data - e.g. other computers, radios, DIY electronics or whatever else you can imagine. It probably works the best, if the hardware is "simple" and have good documentation available, like schematics, and if it is something you need to revisit multiple times - then you can add the needed information yourself, and use it for easy future reference.
- Installation and usage
- Built-in hardware and boards
- Data contributions being worked on currently
- Requirements
- Help wanted
- Contact developer
- Technical topics
- Information automatically collected by CRT
- Commandline parameters
- How to contribute with data to CRT GitHub repository?
- Compiling for Linux
- Development tools used
- Inspiration for building this application
- Screenshots
Download the newest normal (non-NETA) CRT version from Releases, and install it afterwards. The installation folder cannot be set by the user, and is decided by installation system (Avalonia), but in the Configuration tab you can open the folder where it has its configuration and data files located.
If needed then the data-root folder can be changed via a commandline parameter, view Commandline parameters.
Depending on your configuration settings, then CRT will check for newer data at application launch.
When a new version is released, you can update directly from within the application.
- Amstrad CPC 664
- MC0005A
- Commodore VIC-20
- 250403 (CR)
- Would appreciate help with:
- Oscilloscope baseline for PAL and NTSC
- More data
- Would appreciate help with:
- 250403 (CR)
- Commodore 64
- 250407 (long board)
- Covers all components
- Oscilloscope baseline measurements for PAL and NTSC
- 250425 (long board)
- Covers all components
- Oscilloscope baseline measurements for PAL and NTSC
- 250466 (long board)
- Covers all components
- Oscilloscope baseline measurements for PAL and NTSC
- 250469 (short board)
- Covers all components
- Oscilloscope baseline measurements for PAL and NTSC
- 250407 (long board)
- Commodore 128 and 128D
- 310378 (C128 and C128D, plastic cabinet)
- Covers all components
- Oscilloscope baseline measurements for PAL and NTSC
- 250477 (C128DCR, metal cabinet)
- Covers all components
- Would appreciate help with:
- Oscilloscope baseline for NTSC
- 310378 (C128 and C128D, plastic cabinet)
- None to my knowledge - please let me know, if you are cooking up something
- Operating systems supported:
- Windows 7 or newer (32-bit and 64-bit)
- macOS (64-bit)
- Linux (64-bit)
Note that .NET is embedded in application, which means you do not need to have this installed. It also does mean that even if you have .NET installed on your computer, then it will still use the one embedded in application. As .NET6 is the newest version supported on Windows 7, then this is the .NET version included with the Windows 32-bit installer.
Caution
.NET6 has gone End-of-Life in 2024, and has not received any security hotfixes since then!
If possible then you should use the newer CRT 64-bit installer, which embeds the newest available .NET10 LTS (Long-Term-Support) at release date.
I will for sure keep adding and enhancing data, but if this is only me providing data, then it will take many years before this will reach a "premium level" - if ever 😁 So, I really do hope that the community will contribute, so it quickly can become a good source of information.
Data contribution can be almost anything - tiny and trivial updates (spelling mistakes, wrong technical values or alike) or it can be huge new boards, but I really would like to get a massive amount of quality data, for the benefit of everyone using this. The goal is that it should have (most) relevant data in one place, so it would not be required to go and lookup for other data sources, but of course it also needs to be balanced a little, not overwelming with too much data 🤔
You can help specifically with these topics:
- Do you have higher-quality images of the used schematics?
- Do you have (better) datasheets or pinouts for any of the components?
- Do you see missing components in either the component list or as a highlight?
- Can you improve any data or fill in more technical details anywhere?
There are several ways to get in contact with the developer:
- Direct communication via Retro Hardware Discord channel (accept invite on page)
- CRT "Feedback" tab
- GitHub Issues
I want to be transparent here, and inform that I am gathering information about your setup, at every application launch, where the application does a mandatory "check-in":
- IP address
- Ex.
85.184.162.75 - Used for pinning countries on a worldmap
- Ex.
- Operating system version
- Ex.
Microsoft Windows 10.0.19045 - Used for knowing where to put the most effort
- Ex.
- CPU architechture used (32-bit or 64-bit)
- Ex.
64-bit - Used for knowing how wide usage that pesky self-contained .NET6 has
- Ex.
I am allowing myself to gather this data for me to build the CRT Fun facts page, which is some statistics on usage. As a developer, this is a personal motivational point to see countries using my application and of course one always hope for that "upwards trend usage"... which never happens 🤣 I find this limited non-personal data a fair amount to "pay" for using this application, taking in consideration of the effort being put in to this.
CRT supports currently only a single commandline parameter, where you can specify which data folder you want to use. The data folder is where it place all its files that can be fetched from its online source, and as this can be a lot of data, then maybe in some cases it could be useful to save this somewhere else.
If the path does not exists, it will try and create it.
Parameter examples:
--data-root=/mydata/crt--data-root="D:\My Folder With Spaces\"
One possibility to contribute data is by submitting it directly to the GitHub repository, and in this way you will also be seen as a contributor. There are are some basic steps that you can follow, if you want to contribute data to CRT. It is quite easy, but it does require you have a GitHub account.
- Fork the CRT GitHub repository
- Clone the fork to your local computer
- Create a new branch (important!)
- Do your own modifications:
- Change existing files
- Add new files
- Commit changes to your forked repo and the new branch you have created
- Create a
Pull Request- Important - make sure to validate your data before submitting this pull request, as bad data will be declined
- Await review
There are of course more details to this, but please let me know if this does not work for you.
You can view the details in BUILDING.md
CRT has been developed in Visual Studio Community 2026. Where the old Commodore project was primarily self-develpoped, then this new Classic codebase has been developed primarily with GitHub Copilot, which is why I see myself more as a conductor for this project, rather than the pure developer of this application - all credits to the people behind these LLM models 😁 I have primarily used the Gemini 3.1 Pro model, but also Claude Sonnet 4.6 and in some cases GPT-5.3-Codex (these models will of course change for the future).
NuGet packages used:
I have been repairing Commodore 64/128 computers for some years, but I still consider myself as a beginner in this world of hardware, and as you probably can guess (since I did this application) then I am more a software person. I always forget where and what to check, and I struggle to find again all the relevant ressources and schematics to check, not to mention how to find the components in the schematics. I did often refer to the "Mainboards" section of My Old Computer, and I noticed that Jeroen did have a prototype of an application named Repair Help, and it did have the easy layout I was looking for. However, it was never finalized from his side, so I took upon myself to create something similar, and a couple of years later (a lot of hiatus) I did come up with a very similar looking Windows application named Commodore Repair Toolbox (CRT).
After a year with CRT and due to several questions about "is it Windows only", then I investigated if it was realistic for me to do a native porting to other systems. As I in the same time wanted to explore vibe-coding with the new LLM models, then I decided to give it a go... a complete rewrite based on a new platform (Avalonia), giving me a great opportunity to lurk out previous design flaws in the old project, which was almost completely "hand-written". So, here we are now with a completely new project and natively supporting Windows, Linux and macOS - nice.
Main schematics:
Overview where a lot of component information is garthered:
Resources relevant to the hardware and board:
Configuration options:
Doing a few manual traces:
Component information popup:
