(This was originally posted to Twitter on February 3, 2015.)
February 3, 2015
Today, I’m going to tackle this new-to-me Commodore SX-64 computer. I bought it cheaply from a seller that said it wasn’t working. It has a few faults that we’ll take a look, including the keyboard which has a few unresponsive keys.
(This was originally a Twitter thread on September 23, 2018)
September 23, 2018
On the bench today is a Commodore 64 picked up from @Recta_Pete at Atari Party East 2018. This revision is the cost reduced long board because of the sparse components around the VIC-II. I already spot several problems.
I’ve had this cartridge expander for a few years and always assumed it was commonly known about and that the ROM inside had been dumped. It seems that may not be the case, so this page is to provide the information I have about it.
You’ve just unpacked your new Commodore 1520. It was most likely sold as untested, as-is or condition unknown. You plug in the cable, turn it on, and it buzzes and grinds for a couple of seconds then the red LED on top flashes. Silence. You might be lucky and get a little movement on the print head.
The Commodore 64 CP/M cartridge was released sometime in the early 1980’s, shortly after the introduction of the C64 itself. The cartridge contained the necessary Z80 chip inside to run CP/M software natively. While a novel idea, it was a bit too late with the popularity of CP/M waning which itself had been released almost a decade earlier. To make matters worse, it seems to only work on very early revisions of the Commodore 64. I personally am only able to get it to work reliably on a Rev A motherboard (1982, with no s-video output).
The latest acquisition is the JE520 by Jameco. This external voice synthesizer came in two variants: the JE520-CM for Commodore and JE520-AP for Apple II. The only difference was the interface connection to the computer. The Commodore version, the one I have, connects to the user port while the Apple II version connects via an interface slot card. Otherwise, I believe the rest of the hardware to be the same. I found an advertisement for it in RUN issue 7 1984— it retailed for $115-$150.
I’ve put together a quick program that can convert an .SVG file into data statements that can be used to plot it on a Commodore 1520 Printer/Plotter. The program doesn’t run on the Commodore 64 (yet) but instead runs in the browser. It’s not ready to release yet as it’s fair picky about the types of .SVG files you feed it.
To whet your appetite, I’ve prepared a .D64 disk image that has four BASIC programs that will plot four different Commodore logos.