Date   : Fri, 12 Jan 2007 06:53:24 -0600
From   : julesrichardsonuk@... (Jules Richardson)
Subject: Domesday players and modern hardware

Ian Wolstenholme wrote:
> When I was reading chunks of data into the ARM Co-pro at 8MB
> a time, it was taking about 40 minutes to do the reading, I reckon
> that's about 3.5K per second!

Ouch! Isn't SCSI-1 essentially clocked at 5MHz? In other words, a beeb's quite 
possibly a bottleneck and the player might be able to shift data around at a 
higher rate than the beeb's capable of.

Adding a copro quite possibly makes things worse, as presumably the ADFS code 
driving the SCSI bus is still under the beeb's control, but you've got data 
transfers across the TUBE on top of that...

> I think it's worth bearing in mind that more modern Acorn hardware
> can be a handy stepping stone in transferring the contents of
> the Domesday Discs onto a PC.  You don't necessarily have to go
> from BBC Master 8 bit to PC 32 bit in one go.  If you put a 32-bit
> Acorn in the middle of the process then it might make things
> easier.
> 
> For instance you might be able to connect the LV-ROM up to an
> Archimedes or A5000 with SCSI podule and use a sector editor
> to copy the whole lot onto a hard disc.

I'd wondered that too -  the SCSI side of it would quite possibly "just work" :-)

Unfortunately:

   a) The only 32-bit machines I have here with SCSI are the M4 and A680,
      neither of which are able to run anything "useful"
   b) The only 32-bit machine with Ethernet is the SA-RPC, but it needs a
      disk rebuild (and fingers crossed that the drivers for the Ethernet
      portion are in the public domain)

I could probably get a SCSI podule via the museum for the SA-RPC, but all of 
those sorts of spares are currently off-site with someone up north, so it'd be 
a fair few weeks before I could get hold of one. That may well be my best bet, 
though.

> Or you might be able to do something similar to what I did,
> reading sectors instead of actual files if that's what you need,
> and read the data into the Beeb RAM or preferably a big
> co-processor like the ARM co-pro so you could do 16MB at
> a time

You confuzzled me then - but you're talking about Sprow's ARM copro aren't 
you, not the ARM1 eval kit? :-) (I think the latter won't take more than 2MB 
as standard)

> then send it to an Econet file server and pick it off

Hmm, Econet might be a possibility, assuming it's faster than data transfer 
between drive and beeb anyway.

Another possibility might be if VFS can drive more than a single device on the 
SCSI bus (unlike ADFS) - it *might* be possible to put a more modern hard 
drive on the same bus as the player then, and via VFS do a raw copy from the 
player to the hard disk. Then put the hard disk in a modern PC and do a raw 
copy from it...

> There are ways and means of getting it done and it might
> be more successful to use a two-stage copying process than
> trying to get a PC talking to the LV-ROM player directly.

Indeed. It's just irritating that the 'read' aspect of the player's SCSI 
support looks to be standards-compliant, it's just that I can't get far enough 
to use it as everything modern chokes due to the lack of Inquiry :-(

Will ponder this one in the next few days I think!

cheers

Jules