Date   : Tue, 06 Jun 2006 17:41:42
From   : "David Hunt" <dm.hunt@...>
Subject: Re: Stacking wedges and multiple TUBE connections (Was:

> 1) offer flat-topped upper portions of the cheese wedge cases
> so that they could be stacked? It seems obvious that people
> could easily end up with more than one, and the things just
> don't stack or spread along the desk well!

I agree, not sure if the ribbon on some things would stretch though.

You could chain them together, but you would need some logic to disable the
other devices.

I could understand the Music 500 being in a metal box, the disc drive was a
common addition so it would be a easy to put the Music 500 on top of your
disc drive. The metal box helps with shielding as well. Personally, I like
having a cheese wedge on each side of the Beeb, they work well as hand
rests.

>
> 2) Design the TUBE interface so it could handle multiple
> devices (connected up
>   and selectable from the beeb - not necessarily switchable
> without a machine restart though, which would be more work).
> I would have thought right from the TUBE's design phase they
> would have at least had 6502 and Z80 copros in mind, and seen
> that some people would won both. The beeb was a rather
> expensive machine as it was - I can't imagine a few more TTL
> gates to do necessary buffering/selection would have put much
> on the cost, surely?

Doesn't the Tube ULA have a DISABLE line, surely it's a matter of setting
that on one board and unsetting on another, thus allowing you to chain
together as many 2nd Procs as you want. You would still need a hard reset
when you switch between them. Additionally, you probably wouldn't want to
power the cards off the Beebs PSU either, one you can get away with, two -
well - not recommended in hot weather!

Dave ;)