Around 1985 I was saving money to buy a Commodore 64, but it was to expensive, and I bought a ZX Spectrum.
So the ZX Spectrum was my first computer I owned.
I tried to program in assembler, but I didn’t understand the difference of memory access and IO access, as the Z80 deals with this it self, while the 6510 does this with special IO chips like the VIA or CIA.
I didn’t do a lot of mods on this computer, only a reset switch.
And a repair of the 7805 power rectifier that died.