Date   : Mon, 07 Nov 2005 14:36:11 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Switching DFS on Model B

Paul J <peterbilt@...> wrote:
>  How can you switch between different DFS roms installed on a model B ?
 
Most ROMs use b7 and b6 of the ROM workspace pointer at &DF0+r as
enable/disable bits. mdfs.net/Docs/Comp/Econet/Disable shows how
to disable NFS.
 
I don't known if the Solidisk DFS does this. However, you only
want to disable the Acorn DFS and use the newly loaded Solidisk
DFS, so all you need to do is disable the Acorn DFS.
 
If I assume that you have Acorn DFS in rom 15 and Solidisk DFS in
rom 14, you would do the following:
 
*Srload SDFS E        Load the Solidisk DFS to Ram in bank 14
?&DFF=?&DFF OR &40    Disable the DFS in bank 15
<Ctrl-Break>          Reset the computer.
 
Change the &DFF to &DFx where x is the ROM number that DFS is in.
 
You may be able to use Solidisk DFS without disabling Acorn DFS if
the sideways RAM bank is a higher bank than the Acorn DFS. The BBC
will use the highest numbered ROM for anything that appears to be
duplicated. I know this works with Acorn DFS and Watford DFS both
fitted, as this way a requirement with early WDFSs that did not
have the Tube code.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
BBC BASIC for Windows and Internationalisation