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From: akcs.macrokid@hpcvbbs.UUCP (Kevin Vashi)
Newsgroups: comp.sys.handhelds
Subject: RS-232 Interface ?'s.
Keywords: rs-232, io, infra red.
Message-ID: <27e112ba:2441comp.sys.handhelds@hpcvbbs.UUCP>
Date: 15 Mar 91 18:40:06 GMT
Lines: 20

Hello,
      I have a couple of questions about the I/O interface on the
HP-48SX.
  1)  Is the signal from the HP-48SX a true RS-232 signal.
  From an interface posted by somebody from UK (Can't remember the name)
  it seem like that the HP signal is half of RS-232 signal but it occurs
  twice as many times.
  eq:      ----    --------
      ----|    |--|        |------   <--- RS-232 output.

             --     --   --
      ______|  |___|  |_|  |_____    <--- HP Output.

  2) What is the difference between half duplex (as used on HP) and 
full duplex.

Any relevent information will be greatly appreciated.

Thank You,
KLevin Vashi.   INTERNET:  eaeu147@orion.uci.edu.
Kevin Vashi.