I guess I'd be the first computer I've used: A Super-80 (2MHz Z-80) complete with 48k RAM, 300 baud cassette interface and connected to a valve-powered black and white TV (yes, the white dot in the middle of the screen was the last 'pixel' visible after turning it off!)
A bit of background on the Super-80... It was a kit computer sold at Dick Smith stores (Australia & NZ) in the early 80's. My father built it and I programmed it most of the time (BASIC and assembly language). It was designed by the developer of the Microbee computer (also Z-80 based, but not a kit computer). One nifty thing about the Super-80 was that by changing 1 byte in the scratch area of RAM, you could get up to 255-digit precision in mathematical operations. It seemed to work well, albeit slowly as the number of digits increased.
Those were the good old days where you'd be lucky not to have the computer crash at least once in a session. Things are a bit better nowadays...
I may seem old with that blurb, but in my defence, I have never used a teletype or anything to do with card readers :)
Code is untested unless explicitly stated