My memory on the Sinclairs is their keyboards too, horrible, that was the reason I didn't take them serious as a kid (they felt like a Fisher toy), used a ViC20 in a department store to learn coding and then bought an Amstrad CPC - mostly because of the 80 character screen vs. the C64.
Another department store squatter here along with my brother. It was crazy to think this is how we learned to program, but it made sense at the time. We went for the ZX Spectrum and eventually wrote our first commercial game for it [1] with the rubber keyboard, it never bothered me.
The personnel didn't bother with us, they didn't know why the computers where there. Sometimes we even made a joke, coding a 5 minute delay, then some loud sound, turning sound up, blocking RUNSTOP/RESTORE and then waited behind some clothes until the computers started very loud sounds and the personnel didn't know how to turn them off.
And also an upgrade on the ZX81 which was far more basic. Long time ago but if memory serves it was some sort of membrane to indicate key positions which you had to press fairly hard to get to work.
