Computer Kit / Plans

From: Richard Erlacher <richard_at_idcomm.com>
Date: Mon Sep 18 20:28:45 2000

Though I don't personally like the PIC's, they do represent the ultimate in
accesibility. You can get them from Digikey, in the event you don't have a
better or more convenient source, and Radio Shack.com has them in various
Kit forms, though I wouldn't go on record as advising anyone to buy anything
from RS, even RS.com, which I cautiously patronize from time to time, since
they're local.

The Harvard architecture, however, is not particularly rare, however, being
at the heart of nearly every DSP that there is. Moreover, the 8048 and 8051
and all their scions have separate code and data spaces.

If I were starting today with microcontrollers of any sort, I'd be inclined
to take on the SCENIX SX line. They're small, incredibly fast (100 MIPS)
and available in 18, and 28-pin 0.300"-wide dip packaging, and some rather
more difficult-to-use 44 and 52-pin packages for their larger part. The
architecture is very much like the PIC, though it has somewhat more of a
call stack.

What appeals to me about this part over the much more varied PIC series from
Microchip, is that it can emulate devices I can't buy any more, and, I
suspect, can provide functions from an interrupt driven bus interface in the
style of an 8744 or 8742, that will synchronize with a master processor's
bus, perhaps insterting its own wait-states automatically, and, aside from
the time it actually spends processing bus activity, can provide functions
that I never could buy. It would be quite easy to build an 8253 look-alike
that worked conveniently and was 4 bytes deep rather than a mere two. That
would allow for some very precise timing of quite lengthy intervals. There
are lots of things it might be persuaded to do with a little coaxing from
some cleverly written code.

Another one that's getting a lot of press, and hobbyist attention is the
"Rabbit." A web search is the best way to find out about it, though.

Dick

----- Original Message -----
From: <CLASSICCMP_at_trailing-edge.com>
To: <classiccmp_at_classiccmp.org>
Sent: Monday, September 18, 2000 5:08 PM
Subject: RE: Computer Kit / Plans


> * Anyway, I am currently looking for an unbuilt computer kit or plans.
S100
> * bus would be cool, but I don't really care about that or the processor -
> * z80, 6800, 6502 - I iust want a project. Parts should be easy to find
and
> * relatively cheap. I would prefer a serial interface for I/O.
>
> If expandability isn't a prime goal (and this may be the case seeing, as
> you don't care about the bus) you might try playing with one of the
> microcontrollers on the market. A prime example would be one of the
low-end
> PIC's, which are *very* available and *very* cheap. Do a web search for
> "16C84" or "16F84" for one of the most accessible and fun chips available.
>
> If you're worried about the PIC series being "non-classic", don't :-).
The PIC
> architecture has been around for at least 20 years in many variations, and
it's
> one of the few available "Harvard Architecture" chips (i.e. memory space
> separate from data space, a truly "classic" architecture) I can think of
in
> current production.
>
> Tim.
>
>
Received on Mon Sep 18 2000 - 20:28:45 BST