Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!zazen!uwvax!uwslh!lishka
From: lishka@uwslh.slh.wisc.edu (a.k.a. Chri)
Newsgroups: comp.sys.handhelds
Subject: Re: Using HP-48 with modem
Message-ID: <1991Apr12.152924.11046@uwslh.slh.wisc.edu>
Date: 12 Apr 91 15:29:24 GMT
References: <21978@shlump.nac.dec.com>
Organization: Wisconsin State Laboratory of Hygiene
Lines: 31

edp@jareth.enet.dec.com (Eric Postpischil (Always mount a scratch monkey.)) writes:

>Has anybody used the HP-48 with a modem?  The 48 controls the Transmit
>Data line but apparently leaves the Ready To Send and Data Terminal
>Ready lines unchanged.  

I don't see how the hp48sx could ever deal with RTS and DTR because it
only has send, transmit, and ground lines.  Of course, hardware mods
might be able to get it to work, but that seems silly.

>And it seems the modem expects Ready To Send and
>Data Terminal Ready to be asserted -- and their polarity is different
>from that for Transmit Data, which makes me think asserting RTS and DTR
>can't be done just with a couple of jumpers.  Are there any solutions?

"We have ways of making modems talk!"  Some modems allow for DTR and
RTS to be ignored.  There are also ways to jumper RS232 lines together
to "fool" the modem into thinking it received the DTR signal.  I
believe some terminals and/or PC's use only send/transmit/ground to
talk to peripherals with success.

Find a good RS232 guru.  Unfortunately, I am not a hardware type and
it has been too long since I tricked my old Teleray terminal into
thinking DTR was connected to the modem when it wasn't. 

							.oO Chris Oo.
-- 
Christopher Lishka 608-262-4485     It is not safe out here.  It is wonderous,
Wisconsin State Lab. of Hygiene     with treasures to satiate desires both
   lishka@uwslh.slh.wisc.edu        subtle and gross.  But it is not for the
   uunet!uwvax!uwslh!lishka         timid. -- Q