Comment by zabzonk
1 day ago
Yes, it was definitely a thing. The patching code had to be in Z80/8080 machine code. I wrote higher performance keyboard and display routines for my copy of Wordstar using this feature.
1 day ago
Yes, it was definitely a thing. The patching code had to be in Z80/8080 machine code. I wrote higher performance keyboard and display routines for my copy of Wordstar using this feature.
Stuff like that is also cool (reminds me a bit of modding some games), patching machine code to improve performance of a compiled app? Very cool! (My dad might have done that, he has an old ZX81)
But I thought specifically patching something to configure it is such a weird concept that I never would have thought of.
The line between "configuration" and "modding" is pretty thin.
One could say that the difference is whether the developers intended the changes you're making to be possible or not, but what about programs with dedicated modding APIs?
At the time (early to mid 1980s) I think we would say "patching". The Wordstar devs certainly did mean you to do this - the memory locations available were fully documented, and I seem to remember they supplied a small patch utility to incorporate your code into the Wordstar executable.
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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 Then it was very rapidly superseded by the more capable ZX Spectrum machine.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_...
² https://en.wikipedia.org/wiki/Multiface
³ https://en.wikipedia.org/wiki/Romantic_Robot
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.
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