Date   : Sat, 21 Jan 2006 18:14:14 +0000
From   : Andrew Benham <adsb@...>
Subject: Re: eBay What is this?

Ian Wolstenholme wrote:

> Can anyone suggest another way of reading the disc or is it safe to
> assume that there is no data on it?

Lots of OSWORD &72 calls perhaps ??

> It seems that Winchester drives cannot be used interchangeably with
> different controller boards.  A Seagate ST225 formatted on the Adaptec
> board works properly but with the Xebec board just gives a disc error
> and refuses the mount the disc.

The Adaptec ACB4000 stores the geometry of the drive on (I believe)
(part of) physical track 0, and so the sectors reported by the
controller to the host are not the same as on the disk.
The Xebec controller doesn't do this.  So you're right, you can't
move a disk between different controllers and have it just work.

I used a Xebec board for some time on my BBC, until I managed to
find an Adaptec board.
The Xebec board has the drive geometry hard-coded in the EPROM -
I believe it's for a 5MB Shugart drive.  I changed the drive geometry
in the EPROM to match my disk's parameters.  Or you could run a tiny
program to issue the appropriate SASI/SCSI command to set the geometry -
if the program is on the hard disk, it'll need to be at the very start
of the disk so it can be found even though the controller has the
wrong geometry.

> Superform doesn't work with the
> Xebec board, giving "Error 20 in ModeSel".  Is there a formatter for
> use with the Xebec board?

Superform assumes that one is using an Adaptec controller (as indeed
does Acorn's ADFS *VERIFY).  Other controllers don't support the SASI/
SCSI commands needed by SuperForm.
A group in Leicester provided a lot of Winchester utilities (Mike
Tubby is the name I remember) - they should be available on some
of the usual sites.  I've got them - *somewhere*.


Incidently, the URL
    http://www.bitsavers.org/pdf/adaptec/400003-00A_ACB4000UM_Oct85.pdf
gives a better copy of the Adaptec ACB4000 User's Manual than I've
seen before.

And   http://www.bitsavers.org/pdf/xebec/   might be worth a visit too.

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"