From: smithj@jacobs.CS.ORST.EDU (Jeremy Smith)
Newsgroups: comp.sys.handhelds
Subject: Re: HP-48SX comms
Date: 14 Mar 90 08:04:31 GMT
Reply-To: smithj@jacobs.CS.ORST.EDU.UUCP (Jeremy Smith)
Organization: Oregon State University - CS - Corvallis Oregon

>From: pete%slack.uucp@cs.utah.edu (Pete Ashdown)
> 
> Rick Sterling was kind enough to post the pin-outs for the 48's serial
> connector recently.  However, he did not specify what was needed to actually
> make the connector.  Does anyone know the TRaSh-Shack equivalent to plug into
> that hole?  Also, which pin is #1?

&

> From: wscott@EN.ECN.PURDUE.EDU (Wayne H Scott)
> 
> Hello everyone,
> 
> I have a 48sx and am planning on hooking it up to my computer but I just can't
> see spending $35 on a cable I could build myself.
> 
> Is the serial port anything close to a standard connector?  What have other
> people used to jerry rig a connector?


+---------------------------+      HP 48sx   Description    RS232
|     +------+              |      Pin                      equivalent
|     | 1234 |              |      1         Chassis Ground      1
|      \____/               |      2         Transmit data       2
|                           |      3         Receive data        3
+---------------------------+      4         Signal Ground       7

Looking directly into port.

     The above is info received from Rick Sterling.  I made a connector
with it and, together with a null modem cable (crossing lines two and
three), it works like a charm.  I have uploaded and downloaded programs
from my PC to the Charlie.

     I enclose the following warning/disclaimer so that it is freely
distributable:

     [WARNING: The following Rube Goldberg/Heath Robinson/Micky
Mouse/String&sellotape/chewing gum&paperclip procedure is not
recommended, may void HP's warranty, might damage your HP 48sx, and
might even work.  Follow entirely at your own risk.  Any resultant
damage is no fault of the source of this procedure.]
_____
     \
(hp)  |
48sx  |                          ___
      |connector   null modem   / PC
      |                         | RS-232
    4 |---------7 7-----------7 | db 9
    3 |---------3 3-----, ----3 | or
    2 |---------2 2---- `-----2 | db 25
    1 |---------1 1-----------1 | plug
      |                         `---
_____/

     For the connection to the 48's pins: on a regular db 25 connector
there are sockets on the female, and pins on the male.  The sockets are
readily available in packets of 10 in either solder or crimp types (even
from radio schack!).  I think you could find connectors that fit on the
48's pins better, but might have to hunt more.

> From: a309@mindlink.UUCP (George Lin)
>
> Also, for the HP serial plug, I scavanged the connector from a broken floppy
> drive.  And, if I remember correctly, pin #1 is closer to the "F" key.
> (pin #4 is closer to the "A" key)

The sockets have two long 'lips' forming a tube.  I squeezed these together 
slightly with a pair of pliers.
           /  \             / 
          |    |           |  \          end on view
           \  /             \  |         of socket
                              / 
         before           after

     I crimped (in my case, rather than soldered) the four sockets to
four wires, and insulated each connector.  (I just happened to have some
very thin 'ptfe' tubing perfect for the job, but anything to insulate
them from each other will do).  I then placed them on a piece of tape
exactly 2mm apart (which is the distance of the pins from each other, as
close as I could eyeball with a ruler), and then wrapped the tape
around.  The other ends of the wires were connected to the regular db25
serial connector.  Bingo!

            ________________________ 
           //      /      /      /  \
          ||  \   |  \   |  \   |  \ |
          | \  |   \  |   \  |   \  ||
           \__/______/______/______//
   tape-----^
             |      |      |      |
             +------+------+------+
                2mm    2mm    2mm

Yer luvin' Uncle Bert |-)


-- 
Stephen Okay  sokay@mitre.org

"You see, I'm kind of this control freak who likes to create his own
personal hells before the real one can get to him. I like to beat hell
Newsgroups: comp.sys.palmtops