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Fwd: Re: [Altair Computer Club] Re: 88-2SIO Hardware Handshaking Issues

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  • Alan Outhier
    Oops - see below ... Also at each end jumper pins 4-5
    Message 1 of 7 , Jul 3, 2008
      Oops - see below

      Date: Thu, 03 Jul 2008 13:40:27 -0700
      To: altaircomputerclub@yahoogroups.com, altaircomputerclub@yahoogroups.com
      From: Alan Outhier <aouthier@...>
      Subject: Re: [Altair Computer Club] Re: 88-2SIO Hardware Handshaking Issues

      OH! One of my hot buttons, I'll try to keep it short & simple.

      Hopefully, both devices are configured as DTEs (neither is a modem), and both devices are equipped with male db25s (part of being configured as a DTE but some manufactures never understood that).

      Option 1 - buy a commercial null modem cable.

      Option 2 - build your own.
               pin 2 -> pin 3
               pin 3 -> pin 2
               pin 7 -> pin 7

               At each end jumper pins 6-8-20 ('hope I remember this correctly).
               Also at each end jumper pins 4-5

      Don' t try to implement hardware control, it won't buy you anything.

      There's two cents worth for free!

      Al


      At 01:07 PM 7/3/2008, jack99rubin wrote:

      >
      > Mote: My RS-232 book has the following bit of Altair history:
      >
      > "Nothing in the world of microcomputers is more reviled, despised,
      or
      > misunderstood that the RS-232-C interface. Ordinary mild-mannered
      > humans are driven berserk by the experience of connecting their
      > computer equipment. Sometimes this rage gets out of hand:"
      >
      > "A dispute between a customer and a computer store over a $180 bill
      > has ended in tragedy with the fatal shooting of the store's owner.
      >
      > A 42-year-old man, Floyd French of Gladstone, Missouri, was arrested
      > at the scene and later charged with first-degree murder. The victim
      > was the owner of the Altair Computer Center, Henry Phillip Bouldin.
      > According to police, French had bought a computer from Bouldin, then
      > brought in a printer purchased elsewhere and asked that [the store]
      > make the two compatible..."
      > -- Infoworld, June 20, 1983.
      >

      Thanks Tom - I've got nothing to add to that!!
      Have a great holiday weekend, all ye who lurk.

      Jack


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    • Steve
      The preceeding two messages are out of sequence. Al s OOPS message (#1552) is the most recent, which is his modification of his earlier message (#1553).
      Message 2 of 7 , Jul 3, 2008
        The preceeding two messages are out of sequence. Al's "OOPS" message
        (#1552) is the most recent, which is his modification of his earlier
        message (#1553). Because of the order in which I OK'd his messages,
        they got reversed. Message #1552 is the message you should be
        concerned with. Ignore message # 1553.

        This is what happens when you start celebrating July 4 on July 3.

        Steve
        Your confused moderator
        =============================================

        --- In altaircomputerclub@yahoogroups.com, Alan Outhier
        <aouthier@...> wrote:
        >
        > Oops - see below
        >
        > >Date: Thu, 03 Jul 2008 13:40:27 -0700
        > >To: altaircomputerclub@yahoogroups.com,
        altaircomputerclub@yahoogroups.com
        > >From: Alan Outhier <aouthier@...>
        > >Subject: Re: [Altair Computer Club] Re: 88-2SIO Hardware
        Handshaking Issues
        > >
        > >OH! One of my hot buttons, I'll try to keep it short & simple.
        > >
        > >Hopefully, both devices are configured as DTEs (neither is a
        modem),
        > >and both devices are equipped with male db25s (part of being
        > >configured as a DTE but some manufactures never understood that).
        > >
        > >Option 1 - buy a commercial null modem cable.
        > >
        > >Option 2 - build your own.
        > > pin 2 -> pin 3
        > > pin 3 -> pin 2
        > > pin 7 -> pin 7
        > >
        > > At each end jumper pins 6-8-20 ('hope I remember this
        correctly).
        > Also at each end jumper pins 4-5
        >
        > >Don' t try to implement hardware control, it won't buy you
        anything.
        > >
        > >There's two cents worth for free!
        > >
        > >Al
        > >
        > >
        > >At 01:07 PM 7/3/2008, jack99rubin wrote:
        > >
        > >> >
        > >> > Mote: My RS-232 book has the following bit of Altair history:
        > >> >
        > >> > "Nothing in the world of microcomputers is more reviled,
        despised,
        > >>or
        > >> > misunderstood that the RS-232-C interface. Ordinary mild-
        mannered
        > >> > humans are driven berserk by the experience of connecting their
        > >> > computer equipment. Sometimes this rage gets out of hand:"
        > >> >
        > >> > "A dispute between a customer and a computer store over a $180
        bill
        > >> > has ended in tragedy with the fatal shooting of the store's
        owner.
        > >> >
        > >> > A 42-year-old man, Floyd French of Gladstone, Missouri, was
        arrested
        > >> > at the scene and later charged with first-degree murder. The
        victim
        > >> > was the owner of the Altair Computer Center, Henry Phillip
        Bouldin.
        > >> > According to police, French had bought a computer from
        Bouldin, then
        > >> > brought in a printer purchased elsewhere and asked that [the
        store]
        > >> > make the two compatible..."
        > >> > -- Infoworld, June 20, 1983.
        > >> >
        > >>
        > >>Thanks Tom - I've got nothing to add to that!!
        > >>Have a great holiday weekend, all ye who lurk.
        > >>
        > >>Jack
        > >>
        > >>
        > >>------------------------------------
        > >>
        > >>Yahoo! Groups Links
        > >>
        > >>
        > >>
        >
      • Steve
        I have had the opposite experience: Especially at higher Baud rates, software handshaking (XON/XOFF) often failed when hardware handshaking (RTS/CTS) worked
        Message 3 of 7 , Jul 4, 2008
          I have had the opposite experience: Especially at higher Baud rates,
          software handshaking (XON/XOFF) often failed when hardware handshaking
          (RTS/CTS) worked OK. Of course, this was while using equipment 20+
          years ago.

          If all else fails, slow the Baud rate down to 110 or 300, which is slow
          enough that handshaking probably won't be required- the communication
          will be free-running.

          Steve
          ===============================

          --- In altaircomputerclub@yahoogroups.com, Alan Outhier <aouthier@...>
          wrote:
          >
          ...
          > >Don' t try to implement hardware control, it won't buy you anything.
          > >
          ...
        • Tom Sanderson
          I often see handshaking discussed in relation to higher Baud rates. I m never sure about the dividing line between low and high. I think the definition of high
          Message 4 of 7 , Jul 4, 2008
            I often see handshaking discussed in relation to higher Baud rates.
            I'm never sure about the dividing line between low and high. I think
            the definition of high or low depends on the capabilities of the
            devices.

            I think the need for handshaking signals may be a hardware or
            software requirement. My RS-232 book defines RTS and CTS as General
            Purpose. It notes that uses vary widely. In the case of computer to
            computer connection, the need for handshaking signals could depend on
            what software is nunning on each computer.

            My current problem could be a malfunction or mis-configuration of the
            Ethernet Converter. I've been in a Email discussion with technical
            support for weeks. My bigger problem is understanding the
            implementations of 2SIO handshaking signals, especially RTS.

            The 2SIO manual has a chart to indicate the normal interconnections
            to be made if you want to wire your board for RS-232 compatibility.
            The instructions for connecting DTR are not clear. The note that RTS
            also can be used for DTR is not clear.

            I think I mis-read and mis-quoted the the notes about DCD and CTS.
            The signal names have bar drawn over them in the manual notice. Does
            that mean they are inverted?

            Tom





            --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@...>
            wrote:
            >
            > I have had the opposite experience: Especially at higher Baud
            rates,
            > software handshaking (XON/XOFF) often failed when hardware
            handshaking
            > (RTS/CTS) worked OK. Of course, this was while using equipment 20+
            > years ago.
            >
            > If all else fails, slow the Baud rate down to 110 or 300, which is
            slow
            > enough that handshaking probably won't be required- the
            communication
            > will be free-running.
            >
            > Steve
            > ===============================
            >
            > --- In altaircomputerclub@yahoogroups.com, Alan Outhier <aouthier@>
            > wrote:
            > >
            > ...
            > > >Don' t try to implement hardware control, it won't buy you
            anything.
            > > >
            > ...
            >
          • Alan Outhier
            Being a 680 guy, I didn t realize CPM or ??? supported either. Al
            Message 5 of 7 , Jul 7, 2008
              Being a '680 guy, I didn't realize CPM or ??? supported either.

              Al

              At 12:50 AM 7/4/2008, Steve wrote:
              >I have had the opposite experience: Especially at higher Baud rates,
              >software handshaking (XON/XOFF) often failed when hardware handshaking
              >(RTS/CTS) worked OK. Of course, this was while using equipment 20+
              >years ago.
              >
              >If all else fails, slow the Baud rate down to 110 or 300, which is slow
              >enough that handshaking probably won't be required- the communication
              >will be free-running.
              >
              >Steve
              >===============================
              >
              >--- In altaircomputerclub@yahoogroups.com, Alan Outhier <aouthier@...>
              >wrote:
              > >
              >...
              > > >Don' t try to implement hardware control, it won't buy you anything.
              > > >
              >...
              >
              >
              >
              >
              >------------------------------------
              >
              >Yahoo! Groups Links
              >
              >
              >
            • Tom Sanderson
              ... The built in serial port of a MITS/iCOM 680 is wired only for Transmit, Receive. and Ground, so 680 users may miss the fun of handshaking. The 680 UIO
              Message 6 of 7 , Jul 8, 2008
                >
                > Being a '680 guy, I didn't realize CPM or ??? supported either.
                >

                The built in serial port of a MITS/iCOM 680 is wired only for
                Transmit, Receive. and Ground, so 680 users may miss the fun of
                handshaking. The 680 UIO board provides CTS, RTS, and DCD. so it
                would be possible to write software to control these signals.

                Handshaking in BIOS implementations for CP/M serial devices is a good
                question. The ??? programs are another question.

                It should be possible to directly control the Motorola 6850 from a
                user program. That includes ASM programs, CP/M applications,
                and 8080 or 680 BASIC programs. An application could implement
                handshaking using the serial port control register. That assumes the
                signal is available at the connector.

                It looks like the 680 built in port can be wired to control RTS. RTS
                was used for paper tape control.

                Tom

                --- In altaircomputerclub@yahoogroups.com, Alan Outhier
                <aouthier@...> wrote:
                >
                > Being a '680 guy, I didn't realize CPM or ??? supported either.
                >
                > Al
                >
                > At 12:50 AM 7/4/2008, Steve wrote:
                > >I have had the opposite experience: Especially at higher Baud
                rates,
                > >software handshaking (XON/XOFF) often failed when hardware
                handshaking
                > >(RTS/CTS) worked OK. Of course, this was while using equipment 20+
                > >years ago.
                > >
                > >If all else fails, slow the Baud rate down to 110 or 300, which is
                slow
                > >enough that handshaking probably won't be required- the
                communication
                > >will be free-running.
                > >
                > >Steve
                > >===============================
                > >
                > >--- In altaircomputerclub@yahoogroups.com, Alan Outhier <aouthier@>
                > >wrote:
                > > >
                > >...
                > > > >Don' t try to implement hardware control, it won't buy you
                anything.
                > > > >
                > >...
                > >
                > >
                > >
                > >
                > >------------------------------------
                > >
                > >Yahoo! Groups Links
                > >
                > >
                > >
                >
              • Craig Landrum
                ... The serial stuff in CP/M is handled in the customer created (or vendor created) BIOS - the same general area of CP/M that handles the low-level disk I/O
                Message 7 of 7 , Jul 8, 2008
                  On Monday, July 7, 2008 at 1:23 PM, Alan Outhier sent:

                  >Being a '680 guy, I didn't realize CPM or ??? supported either.
                  >
                  >Al

                  The serial stuff in CP/M is handled in the customer created (or
                  vendor created) BIOS - the same general area of CP/M that handles
                  the low-level disk I/O stuff. Most sample BIOS'es don't handle
                  XON/XOFF, (but do seem to handle DEL) and its left as an
                  exercise to the user if they need it. The ones that tend to
                  need it are the ones driving serial-attached printers where
                  it is relatively easy to fill up their input buffers, especially
                  on slower early dot-matrix printers. When full, they would send
                  XOFF to the host computer, and would later send XON to turn the
                  flow of characters back on. Some CP/M example BIOS'es do show
                  handling XON/XOFF for the PRT device.
                  --
                  Craig Landrum
                  Chief Technical Officer
                  mindwrap, inc.
                  Phone: (540) 675-3015 x 229
                  Fax: (540) 675-3130
                  email: craigl@...
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