Date   : Fri, 17 Aug 2007 18:56:50 +0100
From   : info@... (Sprow)
Subject: Acquired Beeb with symptoms...

In article <46C5657A.7060606@...>,
   Jules Richardson <julesrichardsonuk@...> wrote:
> Robert Schmidt-Cisternas wrote:
> > To make it easier to test the speed changes, I used a simple FOR-loop
> > (FOR I%=1 to 10000:NEXT):
>
> Yep, 5 seconds here on a model B with everything in place, with the FDC 
> removed, with the ADC removed, with both FDC and ADC removed - i.e. it 
> seems 
> to make no difference. (Which is interesting in light of Peter's comments 
> about S9)

It will be random whether the NAND gate input floats high or low.

> > - Beeb with ADC out: 4 seconds (Repton is also correspondingly faster,
> > but still unplayable)

> See, that is strange. I'm not quite sure why removing the ADC would 
> partially fix it, as the ADC doesn't appear to generate interrupts anyway

Yes it does, the End-Of-Conversion is wired into one of the CB pins on the
system via. This further suggests something fishy near the system via,
Sprow.