The “Ultimate” SX-64 Project Part 2: A lot has happened!

Note: this is part 2 of me documenting my project to revive a dead Commodore SX-64 portable using an Ultimate 64 replacement motherboard. The SX-64 was designed around custom boards that comprised a complete C64 that fit in the confines of the SX-64’s case. The Ultimate 64 was made to fit in a standard C64 case, which has a lot more breathing room.

Predictably, I failed at keeping this blog up-to-date with my work on the Ultimate SX-64 project. A lot has happened since the last post, and I’m excited to announce that the computer is, well, usable.

Making it all fit has required a little more tinkering than I planned on. I had to remove the original SX-64 vertical cartridge port and relocate the disk drive controller board to where the CPU board used to be. I built extension cables for the power supply and used brackets to extend the case by 4 inches to accommodate the new motherboard.

But, everything works! The Ultimate 64 motherboard is powered by the original power supply and the “multi-button” which controls the Ultimate 64 is now patched into the drive reset button on the front of the case. I can use the original 5 1/4 inch disk drive, or the virtual drive built into the Ultimate 64. The original SX-64 keyboard is connected. And all the video is routed to the original 5 inch blurry CRT.

Using the remastered Ultima IV to test.

All of these changes are reversible, on the SX-64 side at least. I had to solder some wires to the Ultimate 64 board to make the “multi-button” work.

I thought somebody had spilled something on the original glass pane that goes over the CRT, but after disassembling the front of the case, I realized that the chemical tinting mixed with the original glass just didn’t survive 40 years very well. To be honest, not many of us have. So, I have clear replacement glass on the way.

My SX-64 didn’t have a handle when I bought it, so a replacement is also on the way. It’s not a perfect match for the original, but maybe some spray paint can fix that.

And then there’s the matter of the four inch gap that I introduced by extending the case. My plan there is to bend some aluminum flashing to cover it and reinforce it with a wooden framework. Then I’ll extend out some of the ports on the ultimate 64, such as HDMI, USB, and stereo sound. These are things I’m not going to use quite often so I’m fine having the parts on the top and sides of the machine.

Demonstrating my multi-button hack.

But once I get the glass next week, I’ll be in a good position to put it all back together and begin using this awesome machine. I’d love to bring it to World of Commodore in Toronto this year, but I don’t know if I dare try to bring it through airport security or fit it in an overhead compartment!