Date   : Sun, 03 May 2009 21:17:36 +0100
From   : jumbos.bazzar@... (Mark Haysman)
Subject: ADFS 1.53 patch

----- Original Message ----- 
From: "Michael Firth" <mfirth@...>
> It doesn't seem to be limited like this though. In regular '16 bit' mode,
> the HDInit command does have problems getting the geometry of the drive on
> an 8-bit interface, as you suggest (i.e. the 2nd and 4th bytes are wrong,
> usually 0xFF on the Retroclinic interface). However, press 'TAB' in the
> HDInit program, and the display changes to say that its running in 8-bit
> mode, and the 'get geometry' command now works correctly (i.e. the 2nd and
> 4th bytes have valid values in).
>
> Is there some trick in the code to let it read the data twice, but the
> second time have a 1 byte offset, so that the 'other' bytes of the 16 bit
> values become available, or is it just possible to switch an IDE interface
> into 8 bit mode?
>
> Actually for the 1G CF cards I was using, the size wasn't that close to 
> the
> '0x40000000' theoretical value that you suggest, and having the 2nd byte 
> be
> its correct value, rather than zero (which is the only safe option if it
> isn't known), gave a reasonable amount of additional storage.

Here:

http://www.retroclinic.com/misc/IDE_I.jpg

is readout of "Investigate" from HDInit in both 8 and 16 bit modes on a 1GB 
Sandisk CF card. JGH did say to me that he uses some calculation to get the 
correct sizes from the 8 bit investigate, and you can see the 8 and 16 bit 
values for the size are the same. So the data must be there in 8 bit mode to 
get the right values.

Mark.