Date   : Tue, 06 Jul 2004 10:09:53 +0000
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re: Acorn Winchester unit

On Mon, 2004-07-05 at 18:22, Pete Turnbull wrote:
> On Jul 5, 10:06, Jules Richardson wrote:
> > I think the ACW always used an Adaptec board (ACB400 if I remember
> > right), and I have a feeling that's what's in the Winchester unit I
> > found too.
> 
> IIRC stacking filestores may have had SCSI drives but ordinary
> filestores, all Acorn Winchesters, and all ACWs used Adaptec ACB4000s.

Ahh yes, 4000, not 400. I was close :-)

> Xebecs do as well, though if you don't initialise them they default to
> something like an ST506.

For the benefit of those who don't know... ST506 is an interface
standard as well as the model number of the original Seagate drive which
used this interface - just to make things nice and confusing! :-)
 
>   The biggest difference between the Adaptec
> and the Xebec in that regard is that the Adaptec controllers store the
> config information for the drive (heads, cylinders, etc) on the drive
> itself when they format it, and can read it back; the Xebec's have to
> be told by the host every time they are reset (not just once for
> programming).

I seem to remember something in the Omti spec about storing the drive
config on the drive too. 

> > Anyway, my point is that your formatting utilities may be making an
> > assumption that they're talking to an Adaptec bridge board on the
> SCSI
> > bus, not a SCSI hard drive. That may well cause trouble and require
> you
> > to actually format your SCSI drive on a different (non-BBC) machine
> > (e.g. use dd on a Unix system).
> 
> dd won't change the sector size, though.

Nope, but you could use it in place of a native formatter on the BBC to
set up a drive (albeit with 512 byte sectors) with the appropriate data
structures such that you could then drop it straight into a BBC and -
assuming a bodged ADFS that discarded the latter 256 bytes per block on
a read - expect it to work. Saves having to write a new formatter on the
BBC side of things at least.

cheers,

Jules