Date   : Sun, 28 Dec 2008 12:06:31 +0000
From   : zeem.uk@... (Alex Taylor)
Subject: Using stack page for temp vars

2008/12/28 Jonathan Graham Harston <jgh@...>:

> I am **FED** **UP** with calling *commands from View, Diagram, ViewSheet,
> Exmon, Art, any non-BASIC language, and things being corrupted because it's
> trampled over space that BASIC doesn't use, thinking that nothing uses it.

This is really interesting, because I think I may have been guilty of
this (even though I was in my teens at the time). I'm not sure if this
counts though, it was a tiny piece of machine code called from a BASIC
program - is that the same, or does that not count because it's called
from within BASIC?

The program was the only bit of 6502 code I've ever written, in about
1993 or so. It took Mode 0 sprite files from the Archimedes and slowly
copied them to the BBC screen. It was originally all in BASIC, but I
found I had to swap the order of the bits in each byte (I did the
whole thing by trial-and-error), so I rewrote just that part in
machine code, which was much faster. I must still have it on a disk
somewhere. I used it to grab screenshots of video from a digitiser at
school, format them with ChangeFSI, then view them on the Electron,
which at the time was amazing!


-- 
Alex Taylor