Date   : Fri, 10 Feb 2006 23:12:03 +0000
From   : Andrew Benham <adsb@...>
Subject: Re: Linux user-space DFS and ADFS tools?

David Harper wrote:

> In preparation I did a bit of an examination of ADFS disk structure. The
> results might as well be available for anyone interested, so I have just
> converted the summary into HTML and stuck it on the web at:
>    
> http://uk.geocities.com/curried.onion@btopenworld.com/bbc-computer/adfs.html 

Just for completeness, the Archimedes used octets 247-251 on sector 0
and octets 246-250 on sector 1 (marked as 'reserved' in the Master
Reference Manual Part One) to store the disk 'name'.  That's 10
characters max.
They chose to interleave the characters, one should print them in the order:

Sector 0 octet 247
Sector 1 octet 246
Sector 0 octet 248
Sector 1 octet 247
...
Sector 0 octet 251
Sector 1 octet 250


This is for the 'traditional' ADFS disk format, as used on the BBC
machines.  And, I presume, ADFS floppy disks on all later machines ?
I don't have details any more of the newer ADFS formats used on
Archimedes machines.


And, as a reminder, the 'traditional' ADFS disk format demands that
files and directories are stored in contiguous sectors.  And there's
no means to 'map out' defective sectors - even on hard drives (although
hard drives can be made logically perfect 'underneath' ADFS).

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"