Date   : Mon, 13 Jun 2005 12:45:43 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: BBC IDE Drive compatibility list

jgh@... (Jonathan Graham Harston) wrote:
> Full information returned by IDE_Identify:
>   http://mdfs.net/Info/Comp/BBC/IDE/DriveData
 
> Some drives tested don't give "sensible" results, and their format
> capacity has been calculated by doing trail seeks for the end of
> the disk.
 
I've worked out that those drives that don't give "sensible" drive
sizes are actually returning the drive sizes with some of the
bytes reversed!
 
Drives should return the "disk size" as, for example:
 
  &38hi &38lo &37hi &37lo
   &00   &02   &84   &00  -- &00028400 -- 40M
 
But some return it as, for example:
 
  &38hi &38lo &37hi &37lo
   &00   &00   &84   &02  -- &00008402 -- 8M
 
IDEDump now checks for this. If &38lo is zero, it swaps &38lo and
&37lo to get the correct figure.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
RISC OS Choices System - http://mdfs.net/Software/RISCOS