Cogitare computing

Pi1541 Pi Zero support

If you're just looking for the kernel image and circuit diagram click here
unless you want read my entire rant about the project :-)

Back in the beginning of August 2019, Kevin (of Reset Magazine fame) asked me if I was up to anything C64 game related at the moment and I had to decline. But I really wanted to do something Commodore 64 oriented during August (August is C64 Month on Twitter).

A couple of weeks later I got hold of Pi1541 Hat for the Raspberry Pi 3. As you probably know if you're reading this page, the Pi1541 is a Commodore 1541 disk drive emulator which is 100% compatible with the original drive. I knew from reading the Pi1541 page that it had been one of Steve's goals to get it to work on a Raspberry Pi Zero, but he had unfortunately been unable to reach it.

Pi1541 OFFICIAL PAGE

So I thought... I'd like to have a go at that! :-)
Two weeks later, obsessing over optimizations the result was available for public view on Youtube:

After that it was mainly cleanup work and the annoying fact that everyone was getting better results running my code than I was... Turned out the PiHat I bought was broken in more ways than one and after building my breadboard Pi1541 I could verify that I indeed had succeeded in optimizing the code enough to run 100% on a Pi Zero as long as a small overclock was done as well.

The final optimizations were released to GitHub:

Pi1541 Experimental Raspberry Pi Zero support

and merged into Steve's original code base by the end of September.

The official Pi1541 GitHub repository

By then I was pretty tired of the project and felt I'd reached my goal (and spent a month more on the project that I was supposed to), but there was one more thing I wanted to add:

Simple datasette emulation! I don't own a Tapuino so this was something I really needed to have a go at.

and here's a kernel image that should work with the above on a Raspberry Pi Zero

Here's my final Pi1541 Zero build with datasette support  in its home made acrylic shell:

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