Date   : Sat, 25 Jun 2005 00:55:08 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Watford Electronics DFS

J.G.Harston wrote:
> Yep. 16 sectors per track, 320K per side - which neccessitated
> Watford extending the catalogue information to have a DFS disk
> structure larger than 256K.
> 
> Acorn DFS uses 18-bit addresses, so the largest addressable unit
> is 256*2^18-1 bytes -> 256K-1. Watford uses 'spare' bits scattered
> around the catalogue to get 19-bit addresses and access up to
> 512K. I've got the documents somewhere - I need to find them and
> type them up.
 
I've found it: http://mdfs.net/Docs/Comp/Disk/Format/DFS
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
RISC OS Choices System - http://mdfs.net/Software/RISCOS
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