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Re: [midatlanticretro] Re: CP/M CBIOS LST question

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  • Richard Cini
    Thanks Herb. You are right in that the virtual devices like LST can be assigned to other physical devices, but not RDR or PUN (at least from what I read). It s
    Message 1 of 10 , May 26 8:00 PM
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      Thanks Herb. You are right in that the virtual devices like LST can be assigned to other physical devices, but not RDR or PUN (at least from what I read). It's not too big of a deal for me to enable the code and try it out. I guess it would be the same as if I had a switch box on a single serial port and selected what device I used.

      Fun!

      Rich

       



      --- In midatlanticretro@yahoogroups.com, Richard Cini <rich.cini@...> wrote:
      >
      > All --
      >
      > I'm rebuilding my CP/M 2.2 CBIOS and have a question. I have the PUN/RDR
      > devices enabled and pointing to the second port on my console card, and I
      > have the LST device disabled. I never use the PUN/RDR, so I was wondering if
      > there was any reason that I shouldn't change the CBIOS to program the LST
      > device to use the same port. I do have a second port on a second serial card
      > free if I have to use it.
      >
      > Thanks for the advice.
      >
      > Rich
      >

      If I recall, the "IOBYTE" function in later BIOS's permitted reassignment of devices among the LST, PUN, RDR and so on. Check the Digital Research manuals on this, or some of the various "how to write BIOS" CP/M books published. One can also look at BIOS listings in various floppy controller manuals and CP/M implementations, to see some interesting implementations. I think IOBYTE was a feature late to CP/M 2.0 and 2.2.

      Otherwise, you can always poke I/O code into the BIOS memory area on-the-fly, and if you like it modify your BIOS on-disk. Just leave enough space on the disk image of BIOS, to poke it in, and separately of course from the conin/conout/constat code in the BIOS.

      Herb

    • Richard Cini
      All -- I solved the printing problem and now have a working modem and printer for my IMSAI. Everything checked out with the cables and I was able to get CP/M
      Message 2 of 10 , Jun 1, 2013
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        All --

        I solved the printing problem and now have a working modem and printer for my IMSAI. 

        Everything checked out with the cables and I was able to get CP/M to print to another terminal (a laptop). At least the CBIOS code worked.

        I had configured the Interfacer I port for "Terminal/Printer" per the manual which has the effect of NULLing the relevant data/handshaking lines. Once it worked with the laptop, this was the big clue I needed.

        I started playing around with serial cables and adapters and I was ultimately able to get the IBM printer to print through a PPI Microbuffer which I am using to do the serial->parallel conversion, once I connected a NULL modem adapter to the serial input cable. Two NULLs makes, well, no NULL. Straight through is the key, and I needed to change the jumper on the Interfacer.

        I just wanted to get this out on the list to save troubleshooting time for some when using a serial/parallel converter and/or print buffer.

        Now I need something to print! Time to fire up WordStar.

        Rich

        --
        Rich Cini
        Collector of Classic Computers
        Build Master and lead engineer, Altair32 Emulator


      • joshbensadon
        ... Well done Rich! I save a lot of time with RS-232 by using an LED Tester. It has male & female DB connectors and plugs in line to show which lines are
        Message 3 of 10 , Jun 1, 2013
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          --- In midatlanticretro@yahoogroups.com, Richard Cini <rich.cini@...> wrote:
          >
          > All --
          >
          > I solved the printing problem and now have a working modem and printer for
          > my IMSAI.
          >
          > ...
          > NULL modem adapter to the serial input cable. Two NULLs makes, well, no
          > NULL. Straight through is the key, and I needed to change the jumper on the
          > Interfacer.


          Well done Rich!

          I save a lot of time with RS-232 by using an LED Tester. It has male & female DB connectors and plugs in line to show which lines are being driven. Connect it to one side first and observe the TX led is on, then unplug and connect to the other side and observe the RX led is on. If both show TX (or RX) led's on, then you need a NULL (or undo a NULL?).

          I highly recommend you get an 18 LED tester. There are some 9 LED testers that use bi-colour LED's. These suck as you can't see the data pulses unless you have a very keen eye for colour changes (which I don't). The 18 LED tester uses 2 LED's for each line so even at the fastest baud rates, you can easily see a dim glow.

          Here are some links:

          http://www.amazon.com/DB25-Male-Female-Check-Tester-LEDs/dp/B000I96BB0
          $7.65


          http://www.cablesonline.com/rsdbmf18ledm.html
          $6.99

          :)J
        • Richard Cini
          Josh -- Thanks. I m excited to get printing working. ... Agreed. I have one and use it regularly. The other thing I have is an HP Protocol Analyzer 4952A that
          Message 4 of 10 , Jun 1, 2013
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            Josh --

            Thanks. I'm excited to get printing working.

            >>I highly recommend you get an 18 LED tester…

            Agreed. I have one and use it regularly. The other thing I have is an HP Protocol Analyzer 4952A that I got on eBay years ago (look up #300909927435). It does complete line decoding, has tons of test programs and a VT100 terminal. This is usually what I start off with when things don't work the first time. It might be overkill but it allows me to visualize what's going on.

            Rich

            --
            Rich Cini
            Collector of Classic Computers
            Build Master and lead engineer, Altair32 Emulator


          • Dave McGuire
            ... I m sorry but I have to disagree here. 99% of RS232 troubleshooting involves looking at the static states of signals, not looking for fast transitions due
            Message 5 of 10 , Jun 1, 2013
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              On 06/01/2013 09:17 AM, joshbensadon wrote:
              > I save a lot of time with RS-232 by using an LED Tester. It has male
              > & female DB connectors and plugs in line to show which lines are
              > being driven. Connect it to one side first and observe the TX led is
              > on, then unplug and connect to the other side and observe the RX led
              > is on. If both show TX (or RX) led's on, then you need a NULL (or
              > undo a NULL?).
              >
              > I highly recommend you get an 18 LED tester. There are some 9 LED
              > testers that use bi-colour LED's. These suck as you can't see the
              > data pulses unless you have a very keen eye for colour changes (which
              > I don't).

              I'm sorry but I have to disagree here. 99% of RS232 troubleshooting
              involves looking at the static states of signals, not looking for fast
              transitions due to character transfer on the TxD and RxD lines. As long
              as one end is driving TxD and the other end is driving RxD, your data
              lines will be fine. (wiring-wise)

              That said, though, if a different one works better for you, more power
              to you. But my own opinion is that the nine-LED ones are far from
              useless; in fact they're all I use anymore.

              Either way, though, something to indicate the states of the lines is
              indispensable for RS232 interfacing. They're so cheap and so necessary
              that there's really no excuse for not having one.

              -Dave

              --
              Dave McGuire, AK4HZ
              New Kensington, PA
            • Brian Schenkenberger, VAXman-
              ... Wow. Apparently, one can still buy the breakout box model I have had for probably 2 decades or more:
              Message 6 of 10 , Jun 1, 2013
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                Dave McGuire <Mcguire@...> writes:

                >On 06/01/2013 09:17 AM, joshbensadon wrote:
                >> I save a lot of time with RS-232 by using an LED Tester. It has male
                >> & female DB connectors and plugs in line to show which lines are
                >> being driven. Connect it to one side first and observe the TX led is
                >> on, then unplug and connect to the other side and observe the RX led
                >> is on. If both show TX (or RX) led's on, then you need a NULL (or
                >> undo a NULL?).
                >>
                >> I highly recommend you get an 18 LED tester. There are some 9 LED
                >> testers that use bi-colour LED's. These suck as you can't see the
                >> data pulses unless you have a very keen eye for colour changes (which
                >> I don't).
                >
                > I'm sorry but I have to disagree here. 99% of RS232 troubleshooting
                >involves looking at the static states of signals, not looking for fast
                >transitions due to character transfer on the TxD and RxD lines. As long
                >as one end is driving TxD and the other end is driving RxD, your data
                >lines will be fine. (wiring-wise)
                >
                > That said, though, if a different one works better for you, more power
                >to you. But my own opinion is that the nine-LED ones are far from
                >useless; in fact they're all I use anymore.
                >
                > Either way, though, something to indicate the states of the lines is
                >indispensable for RS232 interfacing. They're so cheap and so necessary
                >that there's really no excuse for not having one.

                Wow. Apparently, one can still buy the breakout box model I have had for
                probably 2 decades or more:

                http://www.plccenter.com/en-US/Buy/GC%20ELECTRONICS/43088

                It HAS BEEN indispensable over the years!

                --
                VAXman- A Bored Certified VMS Kernel Mode Hacker VAXman(at)TMESIS(dot)ORG

                Well I speak to machines with the voice of humanity.
              • joshbensadon
                ... In my field, I m connecting to client supplied computers which don t always have the comport(s) configured, so I need to know if the com port is working.
                Message 7 of 10 , Jun 1, 2013
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                  --- In midatlanticretro@yahoogroups.com, Dave McGuire <Mcguire@...> wrote:
                  >
                  > On 06/01/2013 09:17 AM, joshbensadon wrote:
                  > > ...9 LED testers that use bi-colour LED's.... suck as you can't see the
                  > > data pulses unless you have a very keen eye for colour changes (which
                  > > I don't).
                  >
                  > I'm sorry but I have to disagree here. 99% of RS232 troubleshooting
                  > involves looking at the static states of signals, not looking for fast
                  > transitions due to character transfer on the TxD and RxD lines. As long
                  > as one end is driving TxD and the other end is driving RxD, your data
                  > lines will be fine. (wiring-wise)

                  In my field, I'm connecting to client supplied computers which don't always have the comport(s) configured, so I need to know if the com port is working. Static states are enough for just the cabling, but when software doesn't talk to hardware, I need to trace activity on the line. I've seen PC comports lock up before

                  A big part of the reason I don't like the bi-colour LED's is due to my partial red-green colour blindness. I didn't even know I had any partial colour blindness until a few years ago when a coworker noticed I couldn't see certain red LED's when they were lite.

                  But I agree with your remark, "if it works for you...".

                  :)J
                • s100doctor
                  ... I m guessing you got an Epson-produced IBM-branded dot-matrix printer. Entirely reasonable....but since you started another thread on what printer for an
                  Message 8 of 10 , Jun 2, 2013
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                    --- In midatlanticretro@yahoogroups.com, Richard Cini <rich.cini@...> wrote:
                    >
                    > All --
                    >
                    > I solved the printing problem and now have a working modem and printer for
                    > my IMSAI. .... able to get the IBM printer to print through a PPI Microbuffer
                    > which I am using to do the serial->parallel conversion....

                    I'm guessing you got an Epson-produced IBM-branded dot-matrix printer. Entirely reasonable....but since you started another thread on "what printer for an IMSAI", how about revealing the hardware details?

                    Herb Johnson
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