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2SIO Problem

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  • Tom Lake
    I have a 2SIO board with both ports. Port 2 is working with an RS-232 interface at 9600 bps with no problem. Port 1 is set up for 20 mA Current Loop for a
    Message 1 of 6 , Jul 18, 2009
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      I have a 2SIO board with both ports. Port 2 is working with an RS-232 interface at 9600 bps with no problem. Port 1 is set up for 20 mA Current Loop for a Teletype. Right now I can only run VTL-2 from ROM because I believe BASIC requires port 1 to operate (If I'm wrong, please let me know how to load and run BASIC from Port 2!) The Teletype prints the VTL OK prompt but won't accept any input from its keyboard. I can run the Teletype on a PC with the Altair32 emulator and it works fine. This means there's a problem with Port 1 of the 2SIO. Is there some trick to making a Current Loop device work with the 2SIO that wasn't in the Altair manual? If not do you have any suggestions where I could start trobleshooting?

      TIA

      Tom Lake
    • Steve
      Tom, The standard console port for Altair software is octal 020 and 021. Once extended BASIC is loaded, you can use the CONSOLE command to change the main
      Message 2 of 6 , Jul 18, 2009
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        Tom,

        The standard console port for Altair software is octal 020 and 021. Once extended BASIC is loaded, you can use the CONSOLE command to change the main console port to any other serial port. I don't think that has anything to do with your problem, though.

        You may have missed page 1-1 at the beginning of the 2SIO manual, Section 1: Theory of Operation:
        If DATA CARRIER DETECT and CLEAR TO SEND inputs are not connected, they must be jumpered to ground (for TTY and TTL) or to +5V (for RS232).

        I hope this helps.

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

        --- In altaircomputerclub@yahoogroups.com, "Tom Lake" <tlake@...> wrote:
        >
        > I have a 2SIO board with both ports. Port 2 is working with an RS-232 interface at 9600 bps with no problem. Port 1 is set up for 20 mA Current Loop for a Teletype. Right now I can only run VTL-2 from ROM because I believe BASIC requires port 1 to operate (If I'm wrong, please let me know how to load and run BASIC from Port 2!) The Teletype prints the VTL OK prompt but won't accept any input from its keyboard. I can run the Teletype on a PC with the Altair32 emulator and it works fine. This means there's a problem with Port 1 of the 2SIO. Is there some trick to making a Current Loop device work with the 2SIO that wasn't in the Altair manual? If not do you have any suggestions where I could start trobleshooting?
        >
        > TIA
        >
        > Tom Lake
        >
      • Tom Lake
        ... I guess not. How would I load and run BASIC if I can t send from the terminal to the computer? I can t even read in BASIC from port 1 to run it. Is
        Message 3 of 6 , Jul 19, 2009
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          --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@...> wrote:
          >
          > Tom,
          >
          > The standard console port for Altair software is octal 020 and 021. Once extended BASIC is loaded, you can use the CONSOLE command to change the main console port to any other serial port. I don't think that has anything to do with your problem, though.

          I guess not. How would I load and run BASIC if I can't send from the terminal to the computer? I can't even read in BASIC from port 1 to run it. Is there a way to use BASIC if port 1 isn't working? It seems like the MBL ROM is hardcoded for port 1. I can modify the bootloader listed in the manual to use port 2 before I toggle it in but once I get BASIC loaded, how can I tell it to use port 2? I can't use the CONSOLE command if BASIC is expecting all its input from port 1 to begin with.

          >
          > You may have missed page 1-1 at the beginning of the 2SIO manual, Section 1: Theory of Operation:
          > If DATA CARRIER DETECT and CLEAR TO SEND inputs are not connected, they must be jumpered to ground (for TTY and TTL) or to +5V (for RS232).

          Well, thanks, Steve. /DCD and /CTS were connected to Vss rather than ground. Where should they be connected? I tried connecting them to pin 4 of the Molex connector which is listed as Ground but still no luck. The Teletype will print but I can't type on it.

          I double-checked the wiring and it all looks good. Geoff Harrison does very thorough, neat work (he assembled the board for me)
        • Steve
          Tom, That s a good question. Even if you re able to get BASIC to boot, I don t think you can get any further without the main console port being active
          Message 4 of 6 , Jul 19, 2009
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            Tom,

            That's a good question. Even if you're able to get BASIC to boot, I don't think you can get any further without the main console port being active (unless you rewrite BASIC).

            Pin 10 of each Molex connector is hard wired to ground through PCB traces. Pin 4 should also be grounded, but only via a jumper wire from pin 10 to pin 4 on each Molex. Is it possible that the jumper for the port 1 Molex is missing or mis-installed?

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

            --- In altaircomputerclub@yahoogroups.com, "Tom Lake" <tlake@...> wrote:
            >
            > --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@> wrote:
            > >
            > > Tom,
            > >
            > > The standard console port for Altair software is octal 020 and 021. Once extended BASIC is loaded, you can use the CONSOLE command to change the main console port to any other serial port. I don't think that has anything to do with your problem, though.
            >
            > I guess not. How would I load and run BASIC if I can't send from the terminal to the computer? I can't even read in BASIC from port 1 to run it. Is there a way to use BASIC if port 1 isn't working? It seems like the MBL ROM is hardcoded for port 1. I can modify the bootloader listed in the manual to use port 2 before I toggle it in but once I get BASIC loaded, how can I tell it to use port 2? I can't use the CONSOLE command if BASIC is expecting all its input from port 1 to begin with.
            >
            > >
            > > You may have missed page 1-1 at the beginning of the 2SIO manual, Section 1: Theory of Operation:
            > > If DATA CARRIER DETECT and CLEAR TO SEND inputs are not connected, they must be jumpered to ground (for TTY and TTL) or to +5V (for RS232).
            >
            > Well, thanks, Steve. /DCD and /CTS were connected to Vss rather than ground. Where should they be connected? I tried connecting them to pin 4 of the Molex connector which is listed as Ground but still no luck. The Teletype will print but I can't type on it.
            >
            > I double-checked the wiring and it all looks good. Geoff Harrison does very thorough, neat work (he assembled the board for me)
            >
          • Tom Lake
            ... The jumper from pin 10 to pin 4 on port 1 looks the same as the one on port 2 which does work so I d say it s OK.
            Message 5 of 6 , Jul 19, 2009
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              > Pin 10 of each Molex connector is hard wired to ground through PCB traces. Pin 4 should also be grounded, but only via a jumper wire from pin 10 to pin 4 on each Molex. Is it possible that the jumper for the port 1 Molex is missing or mis-installed?

              The jumper from pin 10 to pin 4 on port 1 looks the same as the one on port 2 which does work so I'd say it's OK.
            • Craig Landrum
              Tom; You may want to hunt around for an SIOC card. In the 8800 I sold a while back, I had both the SIO 2 and the SIOC installed. My SIO2 port 1 was attached
              Message 6 of 6 , Jul 20, 2009
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                Tom;

                You may want to hunt around for an SIOC card. In the 8800 I sold
                a while
                back, I had both the SIO 2 and the SIOC installed. My SIO2 port
                1 was
                attached to an RS232 9600 baud Wyse terminal and the SIOC to a 20MA
                Teletype. I was able to specify the colsole at boot time simply by
                flipping the proper front panel switches. That way, if I was doing
                something real, I could boot to the Wyse, and when I wanted to
                show off,
                I could boot to the Teletype. If I recall, this technique
                worked fine
                for BASIC and (I think) Bascomm CP/M, but am not sure about
                Altair DOS.

                I also had a centronics printer attached through Altairs
                centronics board
                and that seemed to work with everything.
                --
                Craig Landrum
                Chief Technical Officer
                mindwrap, inc.
                Phone: (540) 675-3015 x 229
                Fax: (540) 675-3130
                email: craigl@...
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