Subj : Magic smoke update
To   : Spectre
From : Bob Worm
Date : Sat Oct 14 2023 12:57:06

  Re: Magic smoke update
  By: Spectre to Bob Worm on Sat Oct 14 2023 06:27:00

Hi, Spec.

 > That was about 30 years ago... they're not very common here.  I'm
 > unsure I've seen an actual Acorn here at all.

Yeah, to be fair I think Beebs are a *lot* more common. There are tonnes of people on YouTube with Beebs and only a few with Acorn videos, quite honestly I'd never used an Acorn of that vintage until this one, 20 years after I saved it from a skip. I'm not sure I even remember seeing one in context at the time they would have been current.

I used a lot of BBCs in school, though, and thoroughly hated them. "My dad says PCs are much better", etc. Also I can still, in my mid 40s, hear ultrasound like those damn mosquito boxes meant to repel teenagers from shopping areas. The very loud flyback on the ubiquitous CUB monitors used on Beebs was not even close to the top of my hearing when I was a young whippersnapper and so being stuck in a room with 20 of those was chuffing miserable for me.

 > I used to aspire to assembly, but never really got my head around it. Just
 > had to make do with BASIC.  Just remember functionality is 95%, and the
 > other IBM idiom... it might be slow, but it sure is hard to use :)

To be fair BASIC doesn't make much sense to me :) The very first time I went back to BASIC (PRINT "Bob Worm rules" - OK, that works, next job raw disk access...) I got flummoxed by a stupid simple bug in my code.

It turns out with BBC BASIC (and probably many others) that:

"IF a% AND 2 = 0"

....doesn't actually check whether the "2" bit of integer a% is a 1 or a 0. It just goes left to right and effectively does:

"IF a% AND (2 = 0)"

.... since "false" is represented by 0 that becomes:

"IF a% AND 0", so effectively "IF 0", which is "IF false". A long winded way of saying "REM".

I've given up trying to second guess precedence now and just bracket the pants off everything.

BobW
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