» Radio Shack TRS-80 PC-2 Pocket Computer and Plotter Refurbishment

(This was originally a Twitter thread from November 15, 2019.)

November 15, 2019

Say 10 PRINT “Hello, World!” to my new Radio Shack TRS-80 PC-2 pocket computer with printer cassette docking interface. Has BASIC and “2640-character program and data memory”— so a little over 2.5K of RAM. Many thanks to @FloppyDays, it’s all in tip-top shape!

One surprise is the printer is actually a plotter! It’s by Alps (DPG-1301), the same as the one in the Atari 1020, Commodore 1520, etc. but half the size. Instead of 4” wide paper rolls, it uses 2.25” paper. Smallest plotter ever?

The X/Y stepper gears on the PC-2 also split over time but my replacements fit this tiny plotter too. Get a set of 3 printed at Shapeways. Fits Commodore 1520, Atari 1020, and many more Alps plotters.

There’s also a NiCd battery pack lurking inside the cassette interface. Over time these will leak and damage the board. I got lucky and see no signs of damage. Out it goes.

So, as with any new plotter I get, I want to port Schotter (Georg Nees, 1965) over to it. Here’s my BASIC port for the PC-2 (saved and loaded back from cassette) on 2.25” wide paper. There’s a great book called Getting Started on the PC-2 available from Archive.org.

November 16, 2019

Here’s a video of the Radio Shack TRS-80 PC-2 (with the cover off) plotting Schotter.

If you have a Radio Shack PC-2 with the plotter, you can try loading “Schotter” from this “cassette” using your mobile device as the source. Let me know if you get it to load! [warning, loud audio]

[Warning: Loud audio!] Play this sound into your PC-2 to load Schotter.

November 17, 2019

Some more Radio Shack PC-2 plotter prints with BASIC source code. Added some color and some new paper (“adding machine tape”). Each is 2.25” wide.

November 18, 2019

Yet more Radio Shack PC-2 plotter prints. Having fun revisiting these designs in BASIC at 2.25” at a time. And the most permanent output— a hard copy to paper.