I would like some help in hacking an IR printer adapter made for the HP 350c
printer. This is a tiny pc board with a minimum of components connected via
8 wires to a parallel printer connector. I would like to put this to use as
a serial port to IRDA device if possible. Yes, I know there are probably
simpler ways, but this is a very tiny board, and I'd like to learn from it
anyway.

This board is different from others I have torn into. It has an IRDA
transmitter/receiver encoder/decoder similar to but a bit smaller than the
HSDL7001 but only has the numbers R800 and 016A on the back. This is a
through hole, 9 staggered pin device. This adapter was sold by HP so is
this R800 an HP part? Wish I had a data sheet!

In addition there is a small crystal with the frequency 3.68 mhz but no
processor......but does have 3 transistors, 2 resistors, and 2 capacitors
(all surface mount). I think this is the frequency specified for 16xclk.

On the connector side, the only used pins a

18 +5v
19 gnd
10 low-ack
1 low data strobe
13 high
12 high-paper end
19 gnd

19-31-36 (low) (gnd) are all conncted
11-16 connected (gnd)

The presence of the crystal leads me to believe that the baud rate is taken
care of already, on-board. So how do I go about finding where the rx and tx
connections should be. Or is this even possible? The circuit is obviosly
getting it's power (5v) from the printer.

(Incidently, there is a similar adapter for the HP 450c that uses a HSDL
1000 encode/decode, NO crystal or processor, only a couple transistors and a
few passives, but uses only 5 wires from the printer port connector.)
curious!

Thanks
Jim