29 Nov
2007
29 Nov
'07
9:09 a.m.
Tony Duell wrote:
Oh, sure... it's just going to be a while before I can get one shipped here,
and I wondered how practical it was to find a US-spec one on this side of the
pond. Plus I'm sort of curious; the only one I saw in the UK had been reverted
to UK spec, so it was basically a UK machine with all the extra RF shielding
that the US machines had.
As I've stumbled across pretty much every other Acorn in existence at one time
or another, it'd be nice to see a kosher US beeb :-)
You're right about the PSUs though - plus I think that for small SMPSUs (i.e.
without lots of protection circuitry on the 'hot' side) there's some trick to
making them work from 110V anyway (i.e. the '110V operation' stuff can be
added after the fact if needed).
Yep, it's definitely possible to go 'too simple'. Someone's suggestion of
a
VIC 20 was an interesting one. I only ever had one of those years ago, and
confess to never doing anything with it, so know nothing about them other than
a vague notion of them being a 'simplified C64'. I did wonder about an Acorn
Atom, but - whilst less complex than the BBC but still kluge-free - they're
not the most robust of machines (physically or electronically).
True. I'm not sure how the ones I remember from school worked - you didn't get
to see the ICs, so I wonder if under the hood it was something a bit more
complex to get around the blown component problem :-) By the time I saw those
things I'd already taught myself by taking the blown component route... but I
could still appreciate at the time how they were good tutorial aids. (wish I
knew who made them... I'm pretty sure it wasn't unilab, who were the people
who normally did a lot of the school science kit)
Yep, I saw that other post before I saw yours. That's definitely looking like
a good candidate, assuming the hardware doesn't prove to be too rare. I've
never prodded a 6809 myself (just 6502 and Z80), but I guess I could stand to
learn too :-)
cheers
Jules
OK, I've managed to catch up with the thread now. Nice to see so many replies
(I figured it'd generate a few, but I didn't expect this many :-)
A few individual points:
Re. BBC micro: will definitely have one over here at some point. It'd be nice
to find a US-spec one, but I expect they're a little rare even in the US (I've
There's no real need to get a US-spec one. Any beeb other than th very
early ones will have an SMPSU, and there's a clear link to fit to the PSU
board to make it work on 115V mains. And I am sure you cna find soemthing
that will display one of the Beeb's video outputs (darn it, you've got
composited PAL video or serparate TTL-level RGB signals there). only ever seen
one on the UK side). Main worry about the BBC though is that
it's perhaps overkill for that initial learning step (i.e. focus on
ROM/RAM/CPU and basic I/O) but is a fantastic machine once initial concepts
have been grasped. (C64 perhaps falls into the same category as the BBC - it
might be a bit too daunting initially simply because it can do so much more
than the basic stuff)
But if you think of soemthign simpler, then it's either hard to larn to
use (becuase yyou don't have a high-level language in ROM), or it's full
of kludges (I am thinkin of the ZX80 and Jupiter Ace here) that makes it
very hard for a beginner to understnad because the tricks are _not_ in
the introductory books. Maybe a single-board computer based round one of those
microcontrollers
with Tiny-BASIC (Intel 8052 and successors, for example). Hook up a video
terminal, and you can play about flashing LEDs on the I/O pins, etc. And
the circuit should be easy enough to understnad.
That could work. I'm not sure what the best approach is - whether to go the
'simple computer and also try to tech some basic electronics first' route, or
as you say there, try to combine the two initially.
I'm still
not sure how to approach the low-level electronics side of things.
Way back when in the UK, we had some electronics 'kits' at school which had
basic logic gates mounted on a board and allowed kids to jump wires between
them to make circuits (they contained a few LEDs, an LDR, some switches etc.
too). Blue fronts, with the component legends drawn out in white (you couldn't
actually see the ICs themselves). Did something similar exist in US schools?
That sort of thing might be a good practical introduction...
The problem is that many of the better educational kits are now
collector's items in their own right, and hard to find. There is a review
of some of the currently-available ones in the latest Elektor magazine,
BTW, some of thelm look tolerable with a plugblock type breatboard, real
loose components, and so on.
Actually, wahat I'd doo is get a plugblock, a few simple TTL ICs, LEDs,
series resistors, etc, and teach it that way. Yes, you'll get blown
components, but they're cheap enough to replace. I'd still
like to find a 'simple' machine for him to play on - something on a
par with a 48KB Spectrum; i.e. just ROM/RAM/CPU, keyboard, cassette storage,
and TV output. Extra credit for having a 'common' CPU such as the Z80 or 6502
Tandy CoCo 1 or 2? It's essentially the Motorola application circuit for the
6883 SAM, so it's straightforward. OK, the CPU is a 6809, which is not as
common as the others, but it _is_ a nice, easy, CPU to learn.