Date   : Wed, 11 Jan 2006 11:28:18 +0000
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re: eBay What is this?

Pete Turnbull wrote:
> On Jan 11 2006,  0:11, Jules Richardson wrote:
> 
>> The 'controller board' is a Xebec SCSI-ST506 bridge board, designed
> to allow
>> ST506 interface drives to hook up to systems with a SCSI (or SASI)
> bus. It's
>> *not* an Acorn SCSI/Winchester controller (incidentally, if I
> remember right,
>> Acorn used an Adaptec bridge board along with their SCSI interface)
> 
> Yes, Acorn used an Adaptec, an ACB4000, to be precise.  Are you sure
> that's a Xebec board, though?  It doesn't look like the ones I have.

Hmm, it looks like the ones I have here *I think*. I remember the four 40 pin 
IC's in that configuration on the Xebec boards, and that looks like a Xebec 
logo at the top.

I'm not convinced that I remember the boards having an edge connector like 
that though - I'm fairly sure they used an IDC header for both data and 
control cables on the ST506 side. Possibly this is an earlier model.

>  Xebec did SASI, not SCSI, though there's not much practical difference
> on boards that old.

Yes, you're right - been a while since I'd looked at the manual!

>> The hard disk is the interesting bit. Cumana made a second processor
> for the
>> BBC with a 68008 CPU on board, capable of running OS-9 - it sounds
> like this
>> is what this drive came from. Possibly one of the rarest second
> processors
>> made for the BBC.
> 
> Oops, I'd forgotten about that.  Never seen one, but it's been
> mentioned on this list before, so I should have remembered. 

I've got one in the cupboard here... it's a big board that fills the BBC's 
case, plugging into the 6502 socket with the 6502 then plugging into the 
Cumana board. Local memory, plus SASI, floppy and expansion interfaces on board.

Luckily I have the boot floppy so can boot OS-9 on the beeb from that. The 
hard drive for mine is unresponsive though - but as the Cumana board has a 
battery on it I wonder if it stores hard disk params in NVRAM and these have 
long gone. Unfortunately I haven't yet been able to work out if that is the 
case and how the NVRAM's accessed (possibly with a utilities floppy which I 
don't have!)

If anyone ever sees the docs for the board, shout!

cheers

Jules