Date   : Fri, 31 Dec 2010 22:39:32 +0000
From   : jgh@... (J.G.Harston)
Subject: Patching a CF card patched ADFS

Mick Champion wrote:
> be clear, I want to hang the CF HD and ST506 HD's on the same cable and
> switch between the ADFS versions to copy files from my one remaining
> good hard disc before it's too late. Drive 0 died just over a week ago.
...
> given an alternate 1Mhz bus PAL (cheers Mark) for the CF hard disc. That
> PAL alters the CF HD bus address to &FE50-&FE57. Would it be a simple

Simplest way is to use SCSItoIDE[1] to dump the data from the SCSI device
over to the IDE device. That needs an IDE interface where you can change
the address such as the v1.05 8-bit card or the one you have from Mark.

[1]http://mdfs.net/Info/Comp/BBC/IDE/ADFS

> First the easy bit.  How do I change the filing system number on the
> patched ADFS from 8 to something else? ...
> Is it just a single byte in the ROM header that needs altering? If so,

No, you'd need to change the ServiceCall 18 (SelectFS) code, the Sevice
&25 (FSInfo) code and the *command code that recognises "*[F]ADFS".

> Secondly the harder bit I guess. The hard disc is fixed at &FE40 - $FE47
> matter to patch CF ADFS to work from the higher address? I'm happy to
> patch the ROM myself if I knew where to peek and what to poke it with. :-)

If you really want to get your hands dirty, the disassembly is at
http://mdfs.net/Info/Comp/BBC/ADFS  I only got as deep into it as
I needed to replace the hardware drivers. You will discover that
the SCSI code accesses the hardware in many strange and wonderous
ways scattered all around the code. ;)

-- 
J.G.Harston - jgh@...