TRS-80 Model 100 with RARE Bubble Memory Expansion - World's First Laptop

Recently I picked up a couple Model 100 laptops, including one with a very strange expansion unit. This is apparently a "SoundSight Bubble Memory" from 1984. It was a somewhat rare add-on that gave the computer an additional 128k of memory (up from a max of 32k).

While I have not been able to find any information on the Bubble memory online, I did figure out how to interface with it! The associated ROM chip needs to be activated by running "CALL 63012" from BASIC. The user then has a "Bubble" program that lets you view different RAM pages and load/save files to and from the Bubble unit.

I was hoping to also use a TPDD Backpack drive (https://www.soigeneris.com/tandy-tpdd..., but ran into issues with the two Tandy 100s I have. One appears to have a bad memory chip, and the other is such an early model that it has the wrong modem resistors on the serial port. Because of this, I also couldn't connect either of them to a modern computer via serial port. That might have to wait for a future video when I have time to re-solder some resistors.

The Tandy Radio Shack (TRS-80) model 100 is considered by some to be the first "true" laptop, although there were a few other contenders like the Epson HX-20. The series was followed by the model 102 and 200, all of which I actually had when I was a kid in the 90s! They were based on the Kyocerea KC-85 from Japan, and there were a few compatible clones like the NEC PC-8201 and Olivetti M-10. Accessories included a tape drive, floppy disk drive, acoustic modem, printers, etc. There were also many aftermarket ROM expansions and custom software for various uses. These were very popular with travelling salesmen, writers, reporters, and others who needed a computer outside of the office.

Big thanks to FreeGeek Twin Cities (https://www.freegeektwincities.org/) for providing one of these laptops and the Bubble RAM!

Backpack how-to video:    • Quick Start: Backpack Drive SD storag...  
More Backpack documentation: https://github.com/Jeff-Birt/Backpack

I found a ton of TRS-80 software on http://www.club100.org/, so if and when I get the serial port working, I can try out all kinds of games, sound and graphics programs, etc!


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