ZX81 (3.25 MHz Z80 cpu, 1KB of RAM, cassette tape storage). I used it to teach myself Basic when I was 9.
The funniest thing about it was "fast" and "slow" mode. The Z80 was actually used to generate a TV signal, so you had two modes for running programs: In fast mode, the screen went blank, and the cpu just ran your program. In slow mode, the cpu got interrupted regularly to update the screen (which made your program run a lot slower!).
I had the same thing. I also used it to teach myself BASIC... Just because there was no other way to communicate with the computer, really.
My "favorite" part was how long it would take to load a program from the cassette drive. At least 5-6 minutes, during which the screen would go weird colors (with time, you learned to distinguish - white/red means nothing happening, blue/yellow means program is loading) and make really weird sounds...
The funniest thing about it was "fast" and "slow" mode. The Z80 was actually used to generate a TV signal, so you had two modes for running programs: In fast mode, the screen went blank, and the cpu just ran your program. In slow mode, the cpu got interrupted regularly to update the screen (which made your program run a lot slower!).