Date   : Fri, 17 Aug 2007 09:11:56 +0200
From   : robert@... (Robert Schmidt-Cisternas)
Subject: Acquired Beeb with symptoms...

Sprow wrote:
>It's the 6850 ACIA. You can also yank out the ADC (u7002), any speech
chips
>(TMS5220/TMS6100), the disc controller (8271), econet (68B54), and
still
>have something that'll boot. Note, not all these parts may be present
since
>some were offered as upgrades,

To make it easier to test the speed changes, I used a simple FOR-loop
(FOR I%=1 to 10000:NEXT):

- BeebEm: 2 seconds (I'd appreciate a rough measurement from a real
working Beeb, anyone?)
- Beeb with no changes and 8271 out: 7 seconds
- Beeb with ADC out: 4 seconds (Repton is also correspondingly faster,
but still unplayable)

The machine appears to be vanilla - no speech or econet.  

I should also mention that with the ADC out, testing Repton, I plugged
the speaker back in (kids sleeping next door).  Repton's music was
unrecognizable; instead I heard white noise in slow motion, if you know
what I mean - seemingly random notes in a great tempo.

Curious, I plugged the ADC back in (power off, in case you wondered
:-)), reverting the game from unplayable to *really* unplayable.  The
noise from the speaker was the same.  

I tried simple SOUND/ENVELOPEs after a reset, and they worked fine, so
Repton might be doing something funky.

I've noticed that the joystick port is very worn - maybe something
connected that fried the ADC (and more).


Cheers,
Rob

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