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how to use a null modem (google is not my friend)

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  • Joe Giliberti
    I want to use a null modem cable to get files onto an HP Omnibook with DOS/Win 3.11 from an Win XP system. I have googled, to no avail. I grew up in the USB
    Message 1 of 9 , Aug 24, 2009
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      I want to use a null modem cable to get files onto an HP Omnibook with DOS/Win 3.11 from an Win XP system. I have googled, to no avail. I grew up in the USB era. Enlighten my ignorance, please
    • Ray Sills
      Hi Joe: A null modem is simply a way to patch or cross over the receive and transmit data lines. So, the RX line at one end goes to the TX line at the
      Message 2 of 9 , Aug 24, 2009
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        Hi Joe:

        A null modem is simply a way to patch or "cross over" the receive and
        transmit data lines. So, the RX line at one end goes to the TX line
        at the other, etc. See: <http://www.diyha.co.uk/electronics/
        comm1.html>. Some apps and some machines don't care about the DTR
        and the CTS lines, so you might only need pin 5 to 5 (ground) and pin
        2 to 3 and pin 3 to 2.

        73 de Ray

        On Aug 24, 2009, at 9:13 PM, Joe Giliberti wrote:

        >
        >
        > I want to use a null modem cable to get files onto an HP Omnibook
        > with DOS/Win 3.11 from an Win XP system. I have googled, to no
        > avail. I grew up in the USB era. Enlighten my ignorance, please
        >
        >
        >
      • B Degnan
        ... I never used a dull modem cable to transfer files in the 3.11 days. I always used a program called Laplink and the associated blue cable that came with it.
        Message 3 of 9 , Aug 24, 2009
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          Joe Giliberti wrote:
          I want to use a null modem cable to get files onto an HP Omnibook with DOS/Win 3.11 from an Win XP system. I have googled, to no avail. I grew up in the USB era. Enlighten my ignorance, please
          _
          I never used a dull modem cable to transfer files in the 3.11 days. I always used a program called Laplink and the associated blue cable that came with it.  Of course you need the Laplink software.  If you can get the software at least, laplink will copy files over a straight serial cable albeit slower (not a null modem cable, the 7/8 pins are crossed. 

          There may have been versions of Laplink that allowed the use of a null modem cable too.  Don't know, never needed to transfer files that way.  If you can find a straight-through cable I can send you Laplink probably.


          Bill
        • Dan Roganti
          Joe Giliberti wrote:
          Message 4 of 9 , Aug 24, 2009
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            Joe Giliberti wrote:
            I want to use a null modem cable to get files onto an HP Omnibook with DOS/Win 3.11 from an Win XP system. I have googled, to no avail. I grew up in the USB era. Enlighten my ignorance, please



            Did you want to know more about Direct Cable Connection ?
            here's a nice little tutorial about Direct Cable Connection
            http://www.windowsnetworking.com/articles_tutorials/dccmain.html

            Did you want to find out more about the null modem serial cable ?
            The easiest way to determine what kind of serial cable is to check pins 2 and 3 with your multimeter set to continuity.
            If pins 2 and 3 on one end are wired directly to 2 and 3 on the other end, it's a modem cable - not what you want.
            If pins 2 and 3 on one end are wired oppositely to 3 and 2 on the other end, it's a null modem cable - this is what you want.
            hope this makes sense--I never bothered to memorize the markings on cables , it was always gibberish.


            BTW, doesn't the floppy drive still work on that laptop ?
            There's always pkzip for this.


            =Dan

          • Joe Giliberti
            The laptop has laplink on it.
            Message 5 of 9 , Aug 24, 2009
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              The laptop has laplink on it.

              On Mon, Aug 24, 2009 at 9:56 PM, B Degnan <billdeg@...> wrote:
               

              Joe Giliberti wrote:

              I want to use a null modem cable to get files onto an HP Omnibook with DOS/Win 3.11 from an Win XP system. I have googled, to no avail. I grew up in the USB era. Enlighten my ignorance, please
              _
              I never used a dull modem cable to transfer files in the 3.11 days. I always used a program called Laplink and the associated blue cable that came with it.  Of course you need the Laplink software.  If you can get the software at least, laplink will copy files over a straight serial cable albeit slower (not a null modem cable, the 7/8 pins are crossed. 

              There may have been versions of Laplink that allowed the use of a null modem cable too.  Don't know, never needed to transfer files that way.  If you can find a straight-through cable I can send you Laplink probably.


              Bill

            • B Degnan
              ... 2 and 3 crossed not 7 and 8, right? I was wrong.
              Message 6 of 9 , Aug 24, 2009
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                B Degnan wrote:
                Joe Giliberti wrote: I want to use a null modem cable to get files onto an HP Omnibook with DOS/Win 3.11 from an Win XP system. I have googled, to no avail. I grew up in the USB era. Enlighten my ignorance, please
                _
                I never used a dull modem cable to transfer files in the 3.11 days. I always used a program called Laplink and the associated blue cable that came with it.  Of course you need the Laplink software.  If you can get the software at least, laplink will copy files over a straight serial cable albeit slower (not a null modem cable, the 7/8 pins are crossed. 

                2 and 3 crossed not 7 and 8, right?  I was wrong.
              • B Degnan
                ... Good. find a straight-through cable (or put on an adapter of some sort to uncross 2 and 3). You need it running on both systems, and you have to id the
                Message 7 of 9 , Aug 24, 2009
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                  Joe Giliberti wrote:
                  The laptop has laplink on it.

                  Good.  find a straight-through cable (or put on an adapter of some sort to uncross 2 and 3).  You need it running on both systems, and you have to id the correct serial port.  One is host the other is the receive.  If you've got it right you'll see both systems' directory structure on a split screen.   You then tag the files to send over.  Remember that long file names will be truncated. 

                  If you can just run backup/restore it might be easier.  How much data are we talking about?

                  Bill
                • Jim Scheef
                  Joe, Serial file transfer cables are plentiful on eBay. A Belkin cable with both DB9 and DB25 plugs on both ends is $4 plus $10 shipping (a bit high). This is
                  Message 8 of 9 , Aug 26, 2009
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                    Joe,

                    Serial file transfer cables are plentiful on eBay. A Belkin cable with
                    both DB9 and DB25 plugs on both ends is $4 plus $10 shipping (a bit high).

                    This is better - a "Laplink" parallel cable:

                    http://cgi.ebay.com/8-Foot-DB25-Male-to-DB25-Male-LapLink-Cable-PCM-2650-08_W0QQitemZ270447655673QQcmdZViewItemQQptZPCA_Cables_Adapters

                    The Omnibook 425 has a DB9 serial and DB25 parallel. All dedicated file
                    transfer programs like LapLink will use either and a parallel cable will
                    be *much* faster. IIRC, the 425 has Laplink built in. I don't have time
                    to fire mine up to check, but you should be able to find it if it's on
                    the ROM card. It may be ll.exe.

                    But the easiest option is to use a flash card to sneakernet files back
                    and forth. While a fullsize PCCard (PCMCIA) memory card will be hard to
                    find, an adapter for a CF card should be easy to find. This one popped
                    up for an overpriced $27 including shipping. You could even use a CF
                    card as a much larger replacement hard drive.

                    http://cgi.ebay.com/Socket-Communications-AC4000-514-PCCARD-ADAPTER-CF-COMP_W0QQitemZ270312018470QQcmdZViewItemQQptZDigital_Camera_Memory_Cards

                    One more option is infrared. There is an IR port on the 425. If you have
                    another laptop with an IR port, it may be possible to transfer files
                    wirelessly, but IR was always difficult to use.

                    As just about everyone has pointed out, you need a similar program on
                    both ends to make any cable actually move bits.

                    Jim


                    Joe Giliberti wrote:
                    >
                    >
                    > I want to use a null modem cable to get files onto an HP Omnibook with
                    > DOS/Win 3.11 from an Win XP system. I have googled, to no avail. I grew
                    > up in the USB era. Enlighten my ignorance, please
                    >
                  • brian_cirulnick
                    ... I usually zip everything I want to xfer into a single big file (or many small files if I don t have the space for a big file), and then load in PROCOMM on
                    Message 9 of 9 , Aug 26, 2009
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                      --- In midatlanticretro@yahoogroups.com, Jim Scheef <scheefj@...> wrote:
                      >
                      > Joe,
                      >
                      > Serial file transfer cables are plentiful on eBay. A Belkin cable with
                      > both DB9 and DB25 plugs on both ends is $4 plus $10 shipping (a bit high).
                      >

                      I usually zip everything I want to xfer into a single big file (or many small files if I don't have the space for a big file), and then load in PROCOMM on both sides, null modem, 9600 N81, and zmodem xfer and walk away 'till it's done.

                      From my days of doing Linux installs over null modem I have lots of adapters for that...

                      http://www.obsolyte.com/sunFAQ/serial/
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