Date : Thu, 19 Jul 2007 04:13:09 -0500
From : julesrichardsonuk@... (Jules Richardson)
Subject: modern BBC remake
Sprow wrote:
> In article <4f0484feedinfo@...>,
> Sprow <info@...> wrote:
>> I've been chewing it over for at least 5 years under the project
>> name "TurboB". But more on that seperately.
>
> Here goes with my thought processes:
>
> Hardware:
> * Motherboard designed to fit as a drop in replacement to a normal B/B+ case
Hmm. Nice idea, certainly has a certain 'coolness' factor. But at the same
time I suspect there's merit in just stuffing the board in any old Maplin
project box - the important thing for a lot of people is in the hardware
itself, not how it's packaged.
> * 1770 floppy controller
> Possibly in programmable logic as I've not got many chips left, though
> there seem to be some with brokers which would save a lot of effort.
Yes, not sure what the best approach there is. It might be possible to narrow
down a specific modern FDC chip that's known to be FM-compatible, but I'm not
sure about product longevity (not operational lifespan) or whether they're
even for sale outside of PC clone manufacturers.
> * Upgrades
> Space for GoMMC upgrade.
> Space for Econet/Ethernet networking (probably in place of cassette port).
See above about casing - by all means provide a header on the board somewhere
or other mechanism to plug adapter modules in if needed, but I wouldn't bust a
gut over making them a core part of the design (and working out how they mount
in a BBC case) as not everyone will want them anyway.
It's just more time / complexity / cost and not within the task of a "modern
BBC micro 100% compatible with the original". (Econet's probably different as
that did exist on the original machine!)
> * System/user VIA
> Possibly no printer port, replaced by a USB PIC and/or PS/2 keyboard port.
Can't a module be made which makes a PS/2 keyboard look like a BBC keyboard as
far as the hardware's concerned, and it'd just plug in via the normal beeb
keyboard socket? Why waste the printer port on this?
I would have thought that people will still want the ability for the printer
port to be a printer port? Again, can't a printer port to USB module be
designed/built at extra cost for those who want USB on their system? It's an
add-on, not a core feature.
> Software:
> * Based on patched B+ OS
> Software writing takes ages, certainly longer than any hardware design, so
> the hardware would necessarily mimic the original machine faithfully with
> any new or enhanced peripherals supported by a paged 'Utils' ROM or small
> patches applied to the existing OS.
Agreed. Minor patching might be required I suppose, but if you can't
essentially drop an original MOS in there and be away then it doesn't bode
well for compatibility!
> Reasons not to do it:
> * The cost of tooling up for a new run of injection moulded cases/power
> supply/keyboards would be ?10,000's, so to get it cased would involve
> sacrificing a working machine's case.
Forget that aspect then; let people who want to put it in an original case do
so. Supply a board that uses a PC keyboard (via the adapter module mentioned
above) and uses 'stock' PSU voltages (so it'll run off a PC power supply or
whatnot). Forget supplying *any* case for the moment.
> * It'd take about 2 years to complete, by which time any likely interest
> may have dwindled (what happened to the Econet <> Ethernet bridge?). If
> I had a completed one now today things might be different...
Your call - I can happily futz around with LS logic but I wouldn't know where
to start with the modern programmable stuff :-) (Might be worth picking Phil
Blundell's brains about this too - he seems to be Mr. "working FPGA stuff in a
nanosecond" ;)
> * Other than the convenience of every known peripheral on one board, it's
> not actually bringing anything new into the world. All of the above can
> be achieved today by one route or another I think.
Absolutely. The OP seemed to be interested for reliability reasons. Personally
I haven't found beebs to be particularly unreliable - yet. Time won't do them
any favours though and ten years down the road things might be different.
> Estimated price:
> A bare PCB, 2 layer of that size is about ?30. Depending on the programmable
> logic device chosen it may need to be 4 to get the traces out, making about
> ?40.
>
> The assembly would take a few hours based on the huge number of components
> (compared with, say, MiniB).
Are we talking acres of surface mount stuff here, or a more traditional DIL
design within the realms of the home constructor? If the latter, it might be
worth offering a price for plans / PCB (and possibly logic programming service
if needed). Obviously some people will want an assembled product, but others
might be able to do that side themselves.
> We'd only be making 10's off I suspect. I estimate ~?300.
That's probably about what a BBC micro cost back in the 80s - that's progress!
;-)
cheers
Jules