Commodore 8010 IEEE-488 Acoustic Modem ?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Oct 20 20:38:35 2004

>
> On Wed, Oct 20, 2004 at 07:46:27PM -0400, Dave Dunfield wrote:
> > Hi Ethan,
> > It's got a regulator, and some logic - a 6402 UART, and another
> > completely unmarked 40-pin chip - I'm guessing it's an PET-IEEE
> > controller of some sort.
>
> OK... the 6402 UART is one of the ones that I think can be interfaced
> to simple logic - i.e., it doesn't _require_ a microprocessor to read

Correct. It's got separate transmit and receive (parallel) data pins,
baud rate clock inputs, word lenght/parity/stop bit configuration pins,
and so on. It's quite easy to connect to random logic.

> or write to it. I think there's one in an IEEE-serial box I have from
> TNW. I know there's no uP in there.

There was a relatively common PET->RS232 interface in the UK called the
B200. It contained a 6402-like UART, a baud rate generator ckip, a couple
of 2708s (one as a PETSCII<->ASCII converter and address decoder, the
other as the handshake state machine logic) and not a lot else. I
hesitate to called it an IEEE488-> RS232 interface, since the handshake
timing was way off, and while it works with PETs, it fails to work with
many other IEEE488 controllers.

>
> As for the 40-pin chip, unless it's something like a 6500/1 (a micro-
> controller-like relative of the 6502, as found in the 1520 plotter),

Unless there's some EPROM/ROM in there, it's unlikely to be a
microprocessor. It might even be a gate array.

> > Other apparent power sources from the connector head off into a maze
> > of op-amps and other analog circuitry, even with schematics it would
> > take a bit of work to figure out what supplies it was designed for...
>
> Hmm... that makes it hard.

Hard, but not impossible. It should be possible to trace the 5 pins of
that DIN socket. I'll bet one of them is ground (which you must be able
to find). You mention a regulator. Where does the output of that go
(+5V line to the lgoic). And does the input come from a pin on the DIN
socket (that should give you a good guess as to what goes in there). Now
look at the power pins to the op-amps. Maybe they go straing to the DIN
socket (in which case I'll go for +/-12V there). Maybe more regulators
(if so, do the inputs come from the DIN sockets). And so on. I suspect it
would be possible to come up with a supply that works.

-tony
Received on Wed Oct 20 2004 - 20:38:35 BST