Date   : Wed, 16 May 2012 10:02:09 +0100
From   : jim@... (Jim Hearne)
Subject: Torch discs.

Thanks Phil,
I'll try that.

Jim

-----Original Message----- 
From: Phill Harvey-Smith
Sent: Wednesday, May 16, 2012 9:35 AM
To: bbc-micro@...
Subject: Re: [BBC-Micro] Torch discs.

On 16/05/2012 08:53, Jim Hearne wrote:
> It happily reads the disks when set to 40 or 80 tracks, the drive has a
> switch for 40 or 80 track (not labelled) but i think it's in the 80 track
> position or when i tried to read 80 tracks it would hit the endstop on the
> drive.
> How can i be sure if they are 40 or 80 track discs ?
> Would a 40 track disc read as 80 tracks have duplicated data for every 
> other
> track or would it come up with read errors ?

Grab yourself a copy of Sydex's Anadisk, the old DOS version, such as :
http://sta.c64.org/dosprg/anad207.zip

Anadisk can analize the disk and will tell you if there is data on all
the tracks, generally a 40 track disk in an 80 track drive would come
read as good tracks interleaved with unreadable or unformatted tracks.

Something like :

Track 0
bad
track 1
bad
track 2
bad

etc

The one exception to this however would be if the disk was initially
formatted as 80 track and then re-formatted as 40. However in this case
the track numbers in the sector headers would be out of sequence so
you'd get :

Track 0 <40
Track 1 <80
Track 1 <40
Track 3 <80
Track 2 <40
Track 5 <80

etc...

Cheers.

Phill.

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