Cody the Computer and Its Keyboard.

A few months ago, I presented Frederick John Milens' initiative to build a small computer in the purest style of the 80s, closely resembling the Commodore 64.

https://www.codycomputer.org/

Since then, the new version of the Commodore 64, the Commodore 64 Ultimate, has been delivered by the brand new entity Commodore.net.

What differentiates Frederick's version is that his creation uses 'real' physical components, even though the video and sound functions, among others, are handled by a Propeller processor. His concept, although not advertised as C64 compatible, nevertheless remains exactly the same style of computer as the original C64.

The version created by the new Commodore entity, for its part, is based on an FPGA design. It is not my intention to prefer one version over the other. Both are interesting. I received the latest C64 and also built a copy of the Cody.

https://www.commodore.net/

Beyond the hardware work, Frederick has done a significant amount of documentation. In fact, the book available in PDF on his website makes it possible to understand absolutely all the hardware aspects of his machine. Additionally, his GitHub repository provides absolutely all the information necessary to build the machine yourself.

As far as I'm concerned, I have only one small criticism of his approach. It concerns the keyboard. I don't see anything interesting about building a keyboard yourself. Unless, of course, it's a very special keyboard like a processor board with a hex keypad. Otherwise, I prefer to use a standard USB keyboard, and besides, it costs less. However, the USB output of the keyboard obviously needs to be adapted. I've already built this type of interface in the past for an MSX machine. On the other hand, I'm not a fan of interfacing with the original input/output port. There can sometimes be synchronization issues.

So what to do for Cody? Well, since all the resources are available on Frederick's GitHub page (Github), I decided to try a different approach, which is to directly provide the received keyboard code onto the processor's data bus. 

For this, I created a small adapter printed circuit board that I will place on the I/O interface circuit socket. It will contain the interface circuit plus the connection to a small external board designed to provide a serial output corresponding to the key codes typed on the USB keyboard.

There's also the video output, which is a bit too 'retro' for my taste, but there are inexpensive converters for this type of video output to VGA. So, I'll maybe look into that later. Since I have put together VHDL resources for creating a relatively universal frame-buffer, I might be able to use these resources as part of the Cody project.