Date   : Mon, 17 Aug 2009 09:39:05 +0100
From   : philb@... (Phil Blundell)
Subject: Hardware Woes

On Sun, 2009-08-16 at 14:38 +0100, Rob wrote:
> Phil?  Got a spare bridge/router/gateway/whatever it is?  I was going
> to buy one anyway, eventually ...

Yes, I can send you one of those.  The firmware is still in a bit of a
state of flux so you will need an AVR programming dongle to update it
with.  If you have a PC with a parallel port then the cheapest/easiest
option is to buy one of these:

http://cgi.ebay.co.uk/STK-compatible-ATMEL-AVR-programmer-AVR-Tiny-Mega_W0QQitemZ310159133250QQ

or build the equivalent on a bit of veroboard (it's just one 74HC244 or
suchlike).  If you only have USB then you might need to spend a little
bit more money and buy something like:

http://cgi.ebay.co.uk/USBasp-USB-ATMEL-AVR-ATMEGA-ISP-Programmer-AVRDude_W0QQitemZ290334632677QQ

> Plan C is to use the RISC PC, but that's not got an econet interface
> in it, so I have the opposite problem: none of the Beebs will work
> with it, which rather defeats the whole point...  I'll probably have
> to use it anyway, to copy the data off the A5000's drive, if I can't
> get that back up and running...

I think I do have a spare RiscPC econet interface lying around
somewhere.  Given that I don't have a RiscPC at the moment, this is
fairly useless to me so you are welcome to borrow it if I can find it,

> Plan E, Can I put a hard disc and an ethernet card in an A3000 ?
> What would I need?

Not easily.  The A3000 only supports one full-size podule as standard,
so either the hard disk or the network card would need to go in the
internal minipodule slot.  Both of those were certainly produced as
minipodules but they tend to be rather rarer than the full-size
versions.

Unfortunately the minipodule socket has a cut-down electrical interface
as well (only 8 bits wide rather than 16) so it isn't just a case of
adapting the connectors.

In case of desperation, it would be possible to fit a backplane to the
external podule socket and plug the two podules into it.  I've done this
in the past but I don't quite remember what was involved in making it
work; I imagine it probably required fitting an additional decoder of
some kind.  (The external podule socket isn't fully buffered and,
technically, you aren't supposed to apply more than one podule's worth
of loading to it.  But in practice, if the internal socket is empty then
you can probably get away with fitting two podules externally.)

Alternatively, in case of continued desperation, it also wouldn't be all
that hard to hand-build an 8-bit IDE interface in minipodule form, which
would allow you to have an internal CF card (or an actual disk if you
preferred).  If you were prototyping it out of veroboard and 74-series
TTL then you probably wouldn't want to have a ROM onboard, which would
require you to have another device to boot from (either floppy or
network would do), but apart from that it'd be fairly straightforward.

Of course, the Econet socket on the A3000 is separate so it would be
straightforward to set it up for either Econet plus Ethernet or Econet
plus hard disk, using a single podule in the external socket.  That
latter might allow you to solve your backup problem if nothing else.

p.