USR lol

[equinox]

At the risk of getting my arse kicked: the Speccy forum has a beautiful thread about "remember when we didn't know how computers worked, and doing USR or OUT was like looking into the mirror crying Bloody Mary".
https://spectrumcomputing.co.uk/forums/ ... 0&start=20

(Was "RANDOMIZE USR" a thing on the Beeb? Maybe not -- I seem to remember a CALL command, which might allow one to hit an asm routine without having to worry about doing something with the return value. On the Speccy, the retval is from Z80's BC register pair, and traditionally we either RANDOMIZE USR [because surely messing with the RNG couldn't matter -- until you wonder why your game is so predictable] or we assign to a variable like LET l=USR x, which is okay but technically displeasing because side-effects. I've bitched about this before, how one can actually get rid of an unwanted value in Speccy BASIC. Maybe BEEP 0*USR x,0.)

On topic (barely): I am going to port the BBC edu games "Podd" and "Dread Dragon Droom" to the Speccy, 80s-style. The first one is satirical, it will only take an afternoon. The second one will take real work. I converted the graphics more than a year ago. I want to do it like it could run in a school. Perhaps on a microdrive even. I haven't measured everything but I think it would at least take two 48K loads -- still, we are a rich school and we have a floppy drive, right? Right.

with love from your Speccy friend, -- equinox

P.S. If you wanted to really mess with the machine, I remember *TV was pretty amazing on the Beeb. Yowww! *TV 144 instant teletext drunkenness. And presumably this was the trick that allowed my favourite Acornsoft "Magic Mushrooms" to make the screen shake if you fell too far.

[tricky]

Good luck with your ports.
*TV takes effect next time you change mode, which clears the screen, but you can do the same thing with "pokes" or VDU statements.
Call doesn't return anything and Usr returns all the registers A,X, Y and the processor's status register

[SteveF]

At the risk of getting my arse kicked: the Speccy forum has a beautiful thread about "remember when we didn't know how computers worked, and doing USR or OUT was like looking into the mirror crying Bloody Mary".
https://spectrumcomputing.co.uk/forums/ ... 0&start=20

I remember this feeling very vividly. I was only a kid and there was no documentation of course; you just had to pick stuff up from the monthly magazines which (perhaps deliberately, perhaps not) always seemed to enjoy the air of mystery even as they were explaining stuff. Even now when I think back there's this weird air of mystery and excitement tied up with my memories of computing back in the 80s.

It's not so iconic but one thing that sticks in my head is a listing in (I assume) Electron User that let you do:

Code: Select all

*LINE This is double height text

to generate double height text. I spent ages trying to figure out why the command was *LINE and how I could change it to *DHEIGHT or something. The word "LINE" did not appear anywhere in the assembly language source code. Nowadays I know *LINE is a special case handled by the OS, but back then it was frustrating witchcraft...