From: sweet@ug.cs.dal.ca (garth r sweet)
Newsgroups: comp.sys.hp48
Subject: Re: Wiring
Date: 30 Sep 92 23:54:59 GMT
Organization: Math, Stats & CS, Dalhousie University, Halifax, NS, Canada


	With regard to making your own serial cables, I have had some
real good luck with just parts from RADIO SHAFT. What I buy is:

	Part			   Cost
DB-25 Kit (No hood) (Female)	Approx $3.00		Total Cost
DP-25 Hood (Optional)		Approx $4.00		$11.00 with
8 pin IC Sockets (DIP style)	$.99 for two		parts to spare!
4 wire phone cable		$2.95 for 25 feet

I Take one 8 pin socket and split it with a hacksaw. This makes a near 
perfect 4 pin connector (right width & spacing ..almost..). I then take
the phone cord and cut about a 12ft chunk from it and solder the four wires
to the 4 pin connector, and then I simply solder the wires on the other end
to four pins from the DB-25 (the correct 4 pins obviously) and assemble the
DB-25 and hood, then I use a glue gun to melt a big glob of glue on the
4 pin connector and voila! a cable. The pin-out I use is from my HP48sx
manual but for those who don't read such things (or don't have it in thiers)
here's the pin out :

              TOP
+------------------------------+ <--Your HP48
+  . . . .                     +
+  1 2 3 4                     +
+			       +
+------------------------------+

 HP Conn		DB-25		Desc
---------	       -------	       ---------------
    1			1		Shield
    2			3		RX (Receive)
    3			2		TX (Transmit)
    4			7		Gnd (Ground)

	The whole process takes maybe 15 minutes (30 at MOST) and costs
peanuts (many people will be able to find these parts at home).

PROBLEMS:
	The IC socket doesn't get a good enough grip and needs to be held
or 'babied' a bit so it doesn't slip off your HP. It's not too bad though
especially if you make sure the 'flared' side of the IC socket is faced 
down. (you will understand when you make one).


  Another Approach: (A better mouse trap?)

	If you have an old Mouse you can live without, your in luck! It's
pratically a cable already. Open the mouse up, most have a 6 pin connector
attaching the mouse cable to the circuit board, this is almost _exactly_
perfect for the HP, simply remove the cable and connector, use a 
file/hacksaw to cut two pins off the 6 pin connector and to touch it up
as required. Find out which wires at the 6 pin connector end go to the
DB-25 pins you need, swap the wires on the 6 pin connector as needed
(I was able to do this without soldering/cutting by pulling the plugs
right out of the 6 pin connector and reinserting them in the right spots) and
Voila! a HP Serial cable. I made one this way in under 10 Minutes!

	BTW I've only had an HP for 3 days now and I've made a cable 
every day (I'm selling them to less 'adventurous' friends!). Let's see
if I sell another 100 cables I'll make back the price of the calculator :-)

+---------------------------+----------------------------------------------+
+ Name : Garth Sweet        + if (you(love(to(C)))) {                      +
+ email: sweet@ug.cs.dal.ca +   honk(loud);                                +
+ phone: 902-865-8987       + }                                            +
+---------------------------+----------------------------------------------+
Newsgroups: comp.sys.hp48