![](https://www.bitwrangler.uk/wp-content/uploads/2021/07/IMG_20210716_175731-1.jpg)
Diagnostics cards are an essential weapon in the retro fixers toolkit. I have quite a few different diagnostics cards for the ZX Spectrum (having fixed quite a few now), and they have been essential; as well as my oscilloscope – but that’s a different blog.
OpenC64Cart
The first card I built was an ‘OpenC64Cart‘. I bought it from eBay without really checking out any information on the card – it was cheap. It was easy to build and works fine 🙂 It’s a basic card and only supports 8KB cartridge images. I currently have it configured with ‘Dead test’ and ‘Diagnostics’, but there is space for another 6 ROM images on the Winbond W27C512 EEPROM if I want others. The only minor issue I have with the card is the fiddly jumpers that need to be set to switch the ROM types.
Versa64Cart
Next, I decided to order a couple of different PCBs from PCBWay. After some research, I selected the Versa64Cart and the Diag64 cart (a derivative of the first). I ordered 10 of each to combine postage and waited for them to arrive from China.
![](https://www.bitwrangler.uk/wp-content/uploads/2021/07/IMG_20210715_174602-1-596x1024.jpg)
Again, the Versa64Cart was easy to build, although the mini pads on the reverse made soldering a little trickier. The cart has more features, supporting both 8KB and 16KB – and looks good in red 🙂 In use, the dip switches make changing the card type a little easier and the addition of solder bridge pads allows the card to be permanently set up to a specific configuration.
Diag64Cart
The final card was a Diag64Cart. This is a derivative of the Versa64Cart specifically designed to use with diagnostics ROMs; like the Open64Cart this one only supports 8KB ROMs.
![](https://www.bitwrangler.uk/wp-content/uploads/2021/07/IMG_20210715_174622.jpg)
The key feature of this PCB is that it is designed to fit inside a couple of standard cheap cases and is specifically designed to run diagnostics software like like Dead Test Rev. 781220 and Diagnostic Rev. 586220.
Conclusions
So far I have only tried the OpenC64Cart in my broken C64 and it works fine. I have made a Versa64Cart and it looks like it might be my new favorite, but only due to its use of DIP switches for easy configuration (I doubt I will use the 16KB ROM feature – but you never know).
I’ll update this blog when I have tried the other two…….to be continued….