Tandy TRS-80 Model 4P

Specifications

I received this computer in mid-December 2022 around the time of my birthday after purchasing it from eBay. It was a bit of a tough time as the surviving dog of the two that came into my life with my then-girlfriend was diagnosed with bone cancer and was due to cross the rainbow bridge in days. In some weird way the computer served as a temporary distraction from the sadness I felt afterwards although the motivation was rather short lived. Music has a tendency to return you to a time and place but I never would have thought a computer would make me think of poor Bailey during his last days every time I powered it on.

The TRS-80 Model 4P is almost the last in line of the Z80 based Tandy computers descended from the original TRS-80, retroactively named Model 1, that was followed by the Model 3 and 4. I was keen on the 4P as it packed a Model 4 in a "luggable" form factor that could easily be set up and put away in minutes. It also had 25 lines of 80 column text, which is lovely, and could run CP/M. Plus it was backwards compatible with the eariler models, meaning it could run a fuckload of games.

My machine is the later "gate array" version that uses custom IC's that replaces a bunch of 74-series TTL, lowering the chip count. It also as a green phosphor monochrome CRT, which I prefer, instead of white and is fully loaded with 128k of RAM. The two Chinon single sided floppy drives in it are non-original and were most likely put in because, by all accounts I read, the original Tandon drives were absolutely shithouse. I can't say that the replacements are too crash hot as I've had to re-lubricate them several times to make them reliable.

The biggest surprise in my machine is the power supply. I have no idea of its history but I'm assuming that the power supply had died at some point as it was replaced with a homemade one. It was built in a large aluminium jiffy box using a toroidal transformer, large bridge rectifier, capacitors and inductors, plus some L296 switching regulators mounted on the lid of the box as a heatsink. Whoever made it knew what they were doing and did a pretty neat job.

I really like this machine a lot. I have a real weakness for green monochrome displays and the chunky graphics characters give games a real charm. For such a primitive machine with no real graphics harware or sprites, the games are surprisingly good. It's also nice using operating systems like LDOS, LS-DOS, and later versions of TRS-DOS which have good features and utilities on par with CP/M which can also run on it.