Date   : Tue, 26 Jul 2005 16:52:50 +0100
From   : Rob <robert@...>
Subject: Re: ARM copros, speech cartridges, real

At 13:34 26/07/2005, Johan Heuseveldt wrote:

>Hi Rob,
>
>[snip my posr re software claiming the tube]
>
>
>This has nothing to do with a selection of a particular CoPro machine.
>It's intended for software protocols not getting mixed up in each other,
>on /that/ particular Tube ULA.
>
>If two protocols would like control over the Tube to do something, they
>would interfere which each other, as the TUBE protocols can't cope with
>more than a single client protocol. So one client protocol has to finish,
>before another one can continue/start.
[snip]

ah, many thanks, that clears that up.  I was assuming it was also used as a 
negotiation with the host as to readiness, whereas it sounds a lot more 
local than that..

> > The doc implies you're unlikely to be refused unless an interrupt routine
> > claimed it first, but I guess this mechanism could also provide a means
> > for multiple processors to cooperate on communications with the host too,
> > assuming the tube code on the host can accommodate it ...
>
>Not only the Tube code can't, but as the Tube code has no knowledge
>about CoPro specifics in the rest of the Beeb, this not possible,
>unless you write a lot yourself.

 From the sounds of it, any use of multiple co-processors is going to 
require some new software support; if only so there's actually a USE for 
having them!

Rob