Comment by dcminter
1 day ago
The ZX81 didn't have so much software around for it - what there was mostly came on tape, or was typed in¹ on the ghastly membrane keyboard, and what there was was very limited in capability (the default RAM size was one kilobyte (yes, just 1024 bytes, though typically you'd buy a "ram pack" upgrade to 16k). Then it was very rapidly superseded by the more capable ZX Spectrum machine. So odds are your Dad didn't patch software on the ZX81 because it was usually already highly optimised to squeeze it into the tiny space available.
What was very common on those devices was using the "poke" command in BASIC to change a handful of values, but while it was possible to change code in this way it was much more common to be changing the value of variables - things corresponding to "number of lives left" and the like. Not all that different.
Fairly quickly, though, the games were entirely in machine code and used fancy loaders (still from tape mostly) so you didn't get access to BASIC. This created a market for devices that let you get at a monitor program - the "Multiface" series of addons². They had at least three generations of that device, but the company slightly weirdly evolved into a music production company³ after that, which is kind of cool.
Er, ok, I'll stop now while I still can...
Edit: PS - you should ask him about it. Tell him another former ZX81 owner says "Hi" and that my fingers still ache from that keyboard. Although I sneer a bit at its capabilities, it kicked off an interest in computing that's still paying the bills 40 something years later...
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¹ https://spectrumcomputing.co.uk/entry/2000265/Book/Not_Only_...
Cool, yeah, he had the 16 kb extension and his own software written on a cassette/tape.
He says hi back, for him it was purely a work machine (PhD in Chemistry, never did anything with computers as in CompSci), he doesn’t remember too much from back then but he said he loved the architecture of it.
He's likely a good bit older than me then - I was about 9 when we got ours. I think "fancy calculator" was probably one of the best ways to use them given their limitations.
Their success was largely down to their very low price point (clever cost-shaving engineering) at a time when there was a huge untapped public interest in computers.