Practical Electronics CHAMP/Tangerine Microtan 65

From: Brian Chase <vaxzilla_at_jarai.org>
Date: Fri May 23 22:58:01 2003

On Fri, 23 May 2003, Vintage Computer Festival wrote:
> On Fri, 23 May 2003, Brian Chase wrote:

> > I'd really like to design and build a PDP-8 clone, since the real
> > ones command such hefty prices on eBay. I've mostly given up on
> > getting my own 8/F or 8/M.
>
> Great idea!

Heh. The 8/F or 8/M would be my ideal choices. They're newer models
but still have proper consoles. The 8/A has that ugly pushbutton thing.
The older models seem to be so highly sought after by collectors that
they're priced beyond what they'd be worth to me. I've been looking for
a fairly simple setup, maybe with a papertape punch/reader for I/O to
provide the collection with some blinkenlights and whirring mechanical
bits.

> > It's a simple enough architecture that it could be done without
> > too much trouble. And I'd have the benefit of being able to make
> > use of the exisiting library of PDP-8 software. The difficult
> > parts are a) knowing where to even begin, b) finding the time to
> > figure out how to do it, and c) finding the time to actually do it.
>
> I'll assume you're talking about the "straight" 8.
>
> There are enough FlipChip modules around that you could probably get
> 90% of the ones you need to make the processor and I/O sections
> without too much trouble. The difficulty will be in sourcing the
> rarer of the modules (as I have found). [...]

If I were to devise my own, I'd not plan on it being a replica of an
existing PDP-8. I'd just like a functionally equivalent system. And
probably more importantly than having the machine, I'd like to learn how
to build a non-trivial processor from the ground up. Along the way I'd
have to pick up the craft of building and testing electronic devices, so
there are lots of nice side-effects.

The SBC-6120 mentioned earlier in this thread is interesting. It does
have the drawback being that it lacks support for a proper blinkenlight
and toggle switch console. Also, using a microprocessor seems a bit
like cheating, too, but I can certainly understand it from the
standpoint of being practical for the designer's needs. At the moment,
given my various resource constraints, I'm torn between going this
route, settling with a PDP-8/A, or continuing on the no-cost route of
using a software based emulator (until a proper system wanders my way.)

Ah well.

-brian.
Received on Fri May 23 2003 - 22:58:01 BST