Date   : Thu, 14 Sep 2006 16:56:48 +0100
From   : "Ian Wolstenholme" <BBCMailingList@...>
Subject: Re: Domesday Disaster

This would make sense, as there seems to be a lot more debris/decay on the
"other" side of the disc than I am trying to read.  I'll try giving it a gentle
clean later.

Best wishes,



Ian

----- Original Message -----
From: Jules Richardson
To:  bbc-micro@...
Sent:  Thu, 14 Sep 2006 14:05:34 +0000
Subject: Re: [BBC-Micro] Domesday Disaster

Ian Wolstenholme wrote:
> It had to happen!  During the last chunk of DATA2 on the
> South side of the Community disc I got "Disc error 3 at :0/0F0948"!!
> 
> Hoping against hope here, but could this be something simple like
> a dirty/dusty disc

Quite possibly. Hmm, don't LV discs track from the outside inwards (unlike CDs 
that go from the inside outwards)? Which if you're doing a raw dump probably 
means any fault is likely near the centre given how far through you got...

 > and if so, what would be the best way to clean
> it and which surface is being read when the disc is in the drive?

The laser reads the underside of the disc. Careful use of a non-abrasive cloth 
and some warm soapy water should do fine for cleaning off dust I'd have thought.

At recommendations of others I've used brass polish before to remove scratches 
from CDs - I'd imagine that LV discs are a similar plastic material and it'd 
work just as well for those (I've not tried it on a LV disc, but I'd be 
prepared to risk it, if that helps!). Silver polish should be fine too - just 
don't use anything like Jif (or Cif or whatever it is these days!) as that'd 
be too abrasive.

I've seen Domesday discs rot from the outer edges - it seems like the sealing 
sometimes gives up along the rim and then they corrode. Having said that the 
museum has one disc like that where the corrosion goes in about 1cm, yet it's 
still readable - I guess that there's quite a big gap from the edge before the 
data starts. If I'm right about the discs tracking from the outside in then 
that's not your problem anyway...

If it comes to it I'm sure there's someone local to you that could lend you a 
disc so you can finish reading!

cheers

Jules