I’m a big advocate for open source. I’ve been using Linux for close on 30 years – yes, Kernel compiling the Slackware Kernel on a 486 with 4M RAM was a nightmare! Linux has been my primary desktop OS for about 20 years. In the past few years, the open source community has matured to the point that the quality of open source software rivals and sometimes exceeds commercial closed-source software.

In the spirit of that great heritage, I had always intended to offer this project fully open sourced, both the software and hardware. The time has come to share some of the inner secrets of the CPC2.

Now that I’ve fully tested and proven the hardware, I proudly present the schematics for the CPC2 and the bill of materials for the project. You can also order the PCB from OSH Park by clicking the lovely OSH Park logo below. Unfortunately, OSH Stencils doesn’t appear to have a project share facility, but if you want to order stencils to replicate this project, leave me a comment below.

One final hardware resource for the project is a shared project on Mouser electronics, also linked below. Note that this is a partial shopping list, and excludes some common electronic spares, such as 100nF caps. Cross check with the bill of materials for a complete list. Sadly components are EOLd (end-of-life) all the time, so you may need to replace some of the components on the list with the contemporary replacements.

With the hardware sorted, you’ll need the FPGA core and firmware to load onto the board and this has been shared on GitHub. At the time of writing, I haven’t issued a push for some time, but I’ll post the code at some point over the next couple of months as the project reaches a conclusion. With many changes between board revisions, it needs a fair bit of clean up before I post the code.

I hope you’ll find this content both interesting, and possibly useful*. If, like me, you enjoy pouring over schematics to understand how something is put together, I hope you’ll enjoy reviewing these files. If you have any questions on the schematics, please post your questions in the comments and I’ll do my best to respond.

Over the next few months, I’ll finish the supervisor code, tackle the last few irritating timing issues with the FPGA core and develop a 3D printed case. I hope to post some CPC464 and CPC2 comparison photos when the case is completed along with some video of the CPC2 in operation!

Last Post <====> Next Post

* YMMV Disclaimer: This project is provided purely for entertainment purposes and in good faith. If you choose to replicate this project, you are responsible for your own project outcome.

Doesn’t time fly? It’s been 6 months since my last post! My only excuse is that I started a new job and learning a new culture and processes is pretty exhausting. I have tended to work on this project during the evening, but kids being what they are, rarely co-operate when you need some project time. Time to work on the CPC2 has been limited indeed.

There’s been a fair bit of activity though, so let’s take you though what has been done.

Continue reading →

Following the last post, I connected the USB packet information to the faked keyboard in the FPGA and managed to get this.

There’s a timing issue that I suspect is interrupt related. The key repeat is extremely slow, and this is mainly driven from the 50Hz interrupt line. I faked this signal, so there’s obviously some work to do there! Stay tuned!

Previous Post <—-> Next Post