Forum Rules and Etiquette

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I can't make John's serial board with His Z-80 Board

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    Hi All;

    I have made some progress, I wrote a very small program, and used the Altair 8800 CPU card and Entered the code by the Front panel..
    The code with the appropiate changes where needed is
    00 3E Mvi A,
    01 00,
    02 DB IN,
    03 A0
    04 3c Inc A,
    05 c3 Jmp,
    06 02
    07 00..

    The changes are to A0 to A1, etc and DB to D3 for in and for out..
    The correct led's light up on the Serial Card, which at least says that the Switches are OK for Addressing..
    So, it looks like it's the Z-80 CPU Card..

    THANK YOU Marty


      How have you got the links set on the serial board for P60 to P63?

      Have you got RTS looped back to CTS and DTR looped back to DCD or not?

      RTS and DTR are outputs from the serial card, whilst CTS and DCD are inputs to the serial card.



        Hi All;

        Dave, Thank You for the Information..

        I will check everything again.. It was working fine just a few days ago or so. and I had been using it to communicate with the Monitor code I had been working with..
        I switched to the program Eprom from Your code, and it still didn't work..
        I got John's System Monitor Board Yesterday, and I have it all built, I hope it can help me find the problem..
        I also am going to refind my code that is just like Your code and modify it to run at 300 Baud, that way I can see the infor5mation go by with the Led's on the RS-232 Indicator module that I have, and see if with that I can spot the Problem..
        I also could be that something in my Serial Card, doesn't like the High speed of 38.4 K Baud, and I need to slow it down a bit..

        THANK YOU Marty
        Last edited by Marty; May 15, 2020, 07:02 AM.


          Hi All;

          I got everything to work again.. I put down on Paper the signals for P60 and P62, and rejumpered the Serial card..

          I got it to work, I then re-made the Monitor to run at 9600 Baud and it now works.. Which is fine for me at the present..

          So, I am back where I was a few days ago..

          THANK YOU Marty


            Hi All;

            I have some Good news, I have two of John's Serial Boards Running on my Altair, at two different Addresses, one is the normal A0-Ax and the other one is 00-0x..

            Now to make the EEprom in the ZFDC Board talk with the Serial Board at '00 Addresses..

            THANK YOU Marty