[BBC-Micro] Disc formats -- DFS/ADFS and the Master Welcome Disc

michael.firth at bt.com michael.firth at bt.com
Fri Jan 22 09:14:58 GMT 2010


> -----Original Message-----
> From: 
> bbc-micro-bounces+michael.firth=bt.com at lists.cloud9.co.uk 
> [mailto:bbc-micro-bounces+michael.firth=bt.com at lists.cloud9.co
> .uk] On Behalf Of Philip Pemberton
> Sent: 22 January 2010 01:35
> To: Jonathan Graham Harston
> Cc: bbc-micro at lists.cloud9.co.uk
> Subject: Re: [BBC-Micro] Disc formats -- DFS/ADFS and the 
> Master Welcome Disc
> 
<snip>
> 
> You mean like this?
> ADFS-L sector addresses --
>    LBA 0 -- t00h0s1
>    LBA 1 -- t00h0s2
>    LBA 2 -- t00h0s3
>    ...
> 
> Other sector addresses --
>    LBA 0 -- t00h0s1
>    LBA 1 -- t00h1s1
>    LBA 2 -- t00h0s2
>    LBA 2 -- t00h1s2
>    ...
> 
No, it works like this (changed to zero based sectors for consistency with other references):

ADFS-L sector addresses:

LBA 00 - t00h0s0
LBA 01 - t00h0s1
LBA 02 - t00h0s2
LBA 03 - t00h0s3
LBA 04 - t00h0s4
LBA 05 - t00h0s5
LBA 06 - t00h0s6
LBA 07 - t00h0s7
LBA 08 - t00h0s8
LBA 09 - t00h0s9
LBA 0A - t00h0sA
LBA 0B - t00h0sB
LBA 0C - t00h0sC
LBA 0D - t00h0sD
LBA 0E - t00h0sE
LBA 0F - t00h0sF
LBA 10 - t01h0s0
LBA 11 - t01h0s1
LBA 12 - t01h0s2

Other sector addresses:

LBA 00 - t00h0s0
LBA 01 - t00h0s1
LBA 02 - t00h0s2
LBA 03 - t00h0s3
LBA 04 - t00h0s4
LBA 05 - t00h0s5
LBA 06 - t00h0s6
LBA 07 - t00h0s7
LBA 08 - t00h0s8
LBA 09 - t00h0s9
LBA 0A - t00h0sA
LBA 0B - t00h0sB
LBA 0C - t00h0sC
LBA 0D - t00h0sD
LBA 0E - t00h0sE
LBA 0F - t00h0sF
LBA 10 - t00h1s0
LBA 11 - t00h1s1
LBA 12 - t00h1s2

i.e. the sectors within a track are always all read together, the difference is whether the addressing is CHS (cylinder then head then sector) or HCS (head then cylinder then sector)

Regards

Michael



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