My memories also include a Color Computer 3 (TRS-80 equivalent), which I still have. I also still have all the floppies, cassettes, and cartridges for it. Poltergeist is one of them. I remember the game vividly, too. I was always confused about what to do. It never made any sense to me so I never played it. I still don't know what the graphics are supposed to represent to this day.
We had a Color Computer 1 from the early '80s until we finally got our first PC Clone in 1989. Sadly, we sold it and all of the accessories (printer, disk drive, cassette drive, ROM packs) to someone my dad worked with.
They had some great "knock-off" arcade games for that machine, especially one for Donkey Kong. The game came on cassette, so to make < ahem > a "back-up" copy, you put it in a dual-cassette deck and recorded the audio data "screeches" to a new cassette.
My uncle had an original Color Computer with 4k of RAM... I remember he was so happy when he got a new chip to upgrade it to 16k RAM -- he had to de-solder and remove the old chip, then solder in the new one.