Date   : Mon, 27 Apr 2009 11:19:46 +0100
From   : bbcmailinglist@... (Ian Wolstenholme)
Subject: ADFS Drive Numbers

There aren't any jumpers on the host adapter boards I have, and I
don't want to go messing about cutting anything on them!  It seems like
the host adapter will only listen to a controller board with ID 0 and the
controller board will only listen to discs with IDs of 0 or 1.  It looks like
I can't plug a second Winchester disc into the back of the first one, even
changing the drive ID of one of them, presumably because both host
adapters are trying to be mapped into the same area of RAM.

I would have thought this would have been possible, though.  Presumably
it wasn't beyond the bounds of possibility when the Acorn Winchester Discs
came out that some installations (like large Econets) might have two
Winchesters connected to the same BBC server?

Having said that, I remember occasionally at School trying to log on in the
computer room and receiving "User not known" and the teacher remembering
that the Girls' Winchester was plugged in, and going to the M128 and
unplugging it and connecting the Boys' Winchester!  (Which was bigger by
the way!)

Could I perhaps connect two controllers to the same host adapter board
with a 50-way cable with two headers?

I've successfully connected two Winchesters to the same Adaptec controller
previously. I was going to do this yesterday to take a backup of the Technomatic
(probably not the most logical thing to do given the hardware problems, but
by far the most straightforward!)

However, like all best laid plans, I found that I only have two "loose" Winchesters
here.  All the other ones have gone into storage, and the two here were formatted
on an ACB4000, so I can't read them on the Technomatic's ACB4070 to see if
there's anything on them before I overwrite them!

Best wishes,



Ian

----- Original Message -----
From: Andrew Benham [mailto:adsb@...]
To: bbcmailinglist@...
Cc: bbc-micro@...
Sent: Sun, 26 Apr 2009 23:01:31 +0100
Subject: Re: [BBC-Micro] ADFS Drive Numbers

Ian Wolstenholme wrote:
> Is there a version of ADFS which can access drives numbered 2&3
> or 6&7, or is there a hardware limitation preventing this?

I've never heard of an ADFS version supporting this.  On the Master
circuit diagram, a third floppy drive select signal is shown, but
the components to achieve this aren't fitted.

> I've just been jiggering about with the Technomatic and if I set the actual
> disc to anything other than 0 or 1, the controller won't recognise it, and if
> I set the controller to anything other than 0, ADFS won't access it (although
> in this case the "Not found" error does go away if I try *MOUNT 2).
> 
> If I were to happen to connect up two separate Winchester units, daisy
> chaining them together (eg. to make a backup of the Technomatic!!)
> what would I need to do to the drive and controller IDs?  I just had two
> Winchesters on the Technomatic Adaptec controller, both set to 0 and
> that gave some very funny results! It worked OK with one drive as 0 and
> the other as 1, but I don't know what would happen if I put another
> Adaptec controller on the 1MHz bus, since changing the Technomatic's
> Adaptec ID doesn't seem to let me access it.

One host adaptor can drive one Adaptec bridge board, and the bridge
board can drive two ST506 hard drives (daisy chain the 34-way control
connection, use unique 20-way data connection per drive).  I've backed
up my BBC Winchester like this in the past.

If you wanted to connect two separate BBC hard disk units, you'd need
to change the address block that one of the host adaptors used on the
1MHz bus.  On the host adaptor circuit diagram I have, a jumper is shown
that allows a different address block on the 1MHz bus.  However the host
adaptor I use doesn't have such a jumper - it would be a case of cutting
a track and wiring to a different point.
Having done this, you'd need an ADFS that could cope with two host
adaptors on different address blocks - and I don't believe such a beast
exists.

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

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