Never knew anyone who owned a ZX80, but a friend in high school had a ZX81 - he even had a plug in 1MB memory pack for it (which would wobble and promptly crash everything unexpectedly) - he was my 'wicked smart' friend who went on to study computer science at the local Technical College.

I never got further than playing games on a 16KB Sinclair Spectrum (mum refused to get me the 48KB model saying 16 was quite enough) - Ultimate games were the hottest around at the time, and were tape loaded too - how many hours did i waste playing Trans Am, and Jet Pac, lol.