Date   : Thu, 14 Sep 2006 15:41:36 +0100
From   : Richard Kilpatrick <oldcomputers@...>
Subject: Re: Domesday Disaster

On 14 Sep 2006, at 15:05, Jules Richardson wrote:

> 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...

I'm trying to remember what the routine to get my system running was,  
but I'm sure it started at the inside from my experiments. This is  
from memory, though, and memory is never that hot.

> 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...

It's a common problem on Laserdiscs. The glue seems to attack the  
aluminium layer in the worst cases.

Richard

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