To:    Andy Statham
       Island School
Fax:   840 1673

From:  Jonathan Harston
       AFE Computer Services
Fax:   +852 850 4555

Date:  13-May-1993

RE:    1.6Mb disks, LoadCMOS & SaveCMOS

  When I wrote my LoadCMOS and SaveCMOS commands, I based them on the
routine in a program called Desktop Utilities which had an option to save
the configuration.  This saves the CMOS bytes in reverse order, so I made my
commands to the same, thinking that this must be the way CMOS files should
be saved.  It actually turnsa out then the !Configure application in RISC-OS
3 saves the CMOS bytes in forward order!  I have now modified the LoadCMOS
and SaveCMOS commands so they will load a CMOS file saved from !Configure.
The immidiate solution to your problem is to do a Delete-Power On, set the
configuration to what you want, and then save it from the command line with
*SaveCMOS, not with the !Configure application.  LoadCMOS will then load it
ok.  When I next come to Island School, I'll bring the new LoadCMOS and
SaveCMOS commands.  Or you could modify them yourself, you need to change
the following:

In LoadCMOS:
FOR X%=0 TO 240
OSCLI"FX162,"+STR$X%+","+STR$(blk%?X%)
NEXT

In SaveCMOS:
FOR X%=0 TO 240
blk%?X%=(USR &FFF4 AND &FF0000)DIV &10000
NEXT

High Density Disks
==================
  I'm not sure what the problem with you 1.6MB disks are, but maybe the
following might be useful.  You should only format 1.6MB (or 1.44MB) on high
density disks, ones with two little holes in them and an 'HD' label.  You
should only format 800K or smaller on normal double density disks, ones with
one little hole in them - the write protect slot.  On some PCs, DOS will
refuse to format a DD disk if you try to do it HD as it can sense the extra
hole in the disk.  On the Arc, I think this may not be the case.  You can
physically format a DD disk as HD, but it will be unreliable.  Even more
unreliable then formatting a 40 track DFS disk as 80 track.  Even worse is
formatting a HD disk as DD, as the magnetic field is stronger, and it
completely magnetises the disk surface and cannot be re-formatted with the
weaker magnetic field used by HD.

However, it is now almost impossible to get 3.5" disk drives that will NOT
do high density, so the replacement drive should be ok (and I would have
expected MSSC to check it with HD before they returned it to you -
obviously, they didn't, or they only had DD disks to test it with).

Howard Wan is now dealing with the ESF requests, so I've passed on the rest
of the fax to him.


Jonathan