Partitions 3.08
===============

* Now supports more than drive 0
* Stupid bug fixed that was breaking rmtidy.

Replacement (and compatible) scsifs for acorn scsi interface
* multiple partitions on any drive
* access to more than 512MB
* backgrounding (read ahead/ write behind) - set *Configure SCSIFSBUFFERS non-zero.
* speed improvement on saving files.
* Source supplied - example of backgrounding with filecore
* (this is a new interface to filecore, that is more flexable than acorns one)

These instructions are fairly terse, but I hope sufficient.

Please note that by necessity scsifs and partform are NOWHERE near fully
tested, and I CANNOT be responsible for loss of data! Having said that they
work for me, and I use scsifs all the time. I have an Acorn SCSI interface
with software containing SCSIDriver 1.01 (26 Oct 1989).

Scsifs is a replacement Acorn scsifs that mounts several partitions on scsi
devices as different drives scsi::4..scsi::7. This allows riscos to access
more than 512MB on a drive - untested - but calculations are in sectors, not
bytes. It also gains over Acorn's version in that it supports
backgrounding, and works around the bug that slows down saving files of a
length not an even multiple of the sector size. ( Saving a 1 byte file used
to take 0.3 sec vs 0.03 sec for 512 bytes on my drive )

It is restricted in that it currently only understands 512 byte blocks (is
anything else ever used?)

Scsifs finds its partitions by using the riscix partition map that is put on
a drive by the SCSIDM partition command, and offering to riscos any
partitions with names starting "RiscOs:" - note that case IS significant.
PARTFORM takes the initial partition title from after the :, so put
something sensible there.

The order of discs is such that base paritions on all existing drives remain
at the same drive numbers, and any extra partitions found are added
afterward. Unfortunately, scsifs is restricted to a total of only 4
drives/partitions by FileCore - though rumour has it this will be fixed.

To put a disc map and empty catalogue on a partition, use the PARTFORM
program, which is a hacked up version of acorn's HFORM. It is *extremely*
minimally tested - but has worked several times for me.
P.S. I currently believe that it may muck up on small (<5MB) partitions, and
produce illegal map bits numbers, which result in FileCore crashing.

Note that the scsifiler module (wot puts up picies of drives on icon bar)
will only notice extra drives if the replacement scsifs is present when the
desktop is entered. It will also give up entirely if there is an error (such
as occurs if its not yet initialised with a catalogue) on any drive, which
is sad.

To put an RMLoad of a new scsifs in a boot file is slightly irritating since
the file will get closed with the departure of the old scsifs. I use:
       set alias$sys Run Boot:ext.scsifs|mObey Boot:Sys
       sys
in one file, and my boot up continues in the file Boot:Sys

Scsifs is compatible in its cmos ram usage with acorn's one, reading the
scsifsdiscs and scsifsdircache values, and using a spare byte that is
obviously there for the purpose of storeing scsifsbuffers. (Its between
scsifsdiscs and scsifsdircache) It ignores scsifsdrive, and also the disc
map sizes that acorn scsifs caches in cmos ram, however, letting filecore
work it out anew each time. This causes no harm. You will have to go back to
acorn scsifs to reconfigure scsifsdrive.

Debugging scsifs (set DEBUG to TRUE near start) needs the buftrace module,
which provides a set of swis callable from nasty contexts which buffer
output until you type *DUMPTRACE. This debug info should survive a soft
reset, but sometimes riscos doesn't :-(

Hope this is useful - please don't hesitate to contact me if there are any
problems, and please email me if you use it successfully so I can collect
evidence that it works!

Thanks must go to Jon Roach of Acorn for help during this project.

Distribution:

This software may be freely redistributed, so long as only a reasonable
copying or media charge is made, and all files I distribute are included. I
retain copyright to the code. Commercial (including magazine) distribution,
or distributing modified versions of this please contact me - I am normally
happy for it to be reused in other free software, but like to avoid deviant
versions of mine causing trouble.

I am not asking for money, but if you like and use it I would be surprised
and amazed by any contributions, and you will receive a disc with latest
versions on. (>2, say)

Me:

Brian.Brunswick@cl.cam.ac.uk
+44 0223 334419

Brian Brunswick
Trinity College
Cambridge
CB2 1TQ
UK

Brian Brunswick
Fairview
Avenue des Hirondelles
Pool-in-WharfeDale
Leeds
LS21 1EY
UK
