Category Archives: Commodre Mods

Pi1541: a cycle-exact 1541 emulator for Raspberry Pi

Steve White has developed a wonderful application for a Raspberry Pi 3: Pi1541

Pi1541 is a cycle-exact emulator for the 1541 disk drive. Have a look-see. If you want to try this out, you’ll need some soldering skills to make the cable that attaches the C64 IEC bus to the Pi’s GPIO.

If you’ve already got Gideon’s 1541 Ultimate, there’s not much call for the Pi1541, but a Pi costs you less and you might have fun with the DIY aspect of putting it together. (The 1541 Ultimate still can’t be beat, especially considering the freezer functions you get with it.)

Also, I haven’t tried the Pi1541 yet, but I suspect the SD2IEC output  from GB Organizer would work well with it. Steve’s Pi1541 seems to work much like an SD2IEC on the computer-side.

Here’s one of Steve’s videos on the project:

C64C Gold: uIEC/SD, JiffyDOS, Reset Switch Commodore mod

The C64C was an update to the C64 that brought a more modern look (for its time) to the Commodore 64. After Commodore finished off its stock of motherboards, it also got a new updated “short board” that cost a lot less to produce. By the time the Commodore 64 was discontinued, they were able to make them at about $20 a pop. Pretty good for something that retailed for about $100.

These short boards were not actually 100% compatible with the older version.  Many of the parts were not interchangeable with older boards, and the famous SID chip was actually changed. (If you’re curious, you can test this with a C64C by playing Impossible Mission. If you can’t hear “stay awhile…. staaaaay forever!” then you have the updated SID chip.) Compatibility with the older C64 approached 100% but didn’t quite get there.

Anyway, this particular model has one great advantage: lots of empty space under the keyboard for modifications! So below is what I did with mine, in video and in higher resolution pictures.

  • Added a reset switch.
  • Replaced the KERNAL ROM with JiffyDOS. (My board did not have socketed chips, so I had to remove the old ROM and install a socket.)
  • Internally mounted a uIEC/SD — a great sd2iec-based device for mass storage from Retro Innovations. Easily the most gratifying part of this project!
  • Installed all four control switches for the uIEC/SD, too, and
  • Gave it a gold paint job with a shiny clear coat.

Video and Pictures follow.

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Commie Red with 1541 Ultimate-I

One of my earliest mod projects is Commie Red.

  • JiffyDOS
  • Reset Switch
  • Sports-car Red Paint Job

Also, this is the C64 that gets the 1541 Ultimate, which you can see in these pictures. My 1541 Ultimate has a specially designed case for earlier units that did not come with a cartridge case.

There are some flaws in my work — I was a bit impatient to complete the painting part of the project and did not take the time to paint the inside of the case first. So if you look for it, you can see the original color in some areas where the case separates.