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Re: [midatlanticretro] 4K BASIC Running on Altair 8800b

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  • Dan Roganti
    http://www.vintagecomputer.net/ragooman/ B Degnan wrote: While we re on the subject of Altairs, tonight I finally got 4K BASIC running on my Altair 8800b. I
    Message 1 of 3 , May 11, 2010

      http://www.vintagecomputer.net/ragooman/
      


      B Degnan wrote:
      While we're on the subject of Altairs, tonight I finally got 4K BASIC 
      running on my Altair 8800b.  I have been working on this for a few 
      weeks.  Dan suggested that there was a grounding problem with the serial 
      cable because I was getting inconsistent results, he also thought it 
      might be the CPU card.
      
      I hung the cable over the chassis rather than through a port in the back 
      of the chassis, and it worked a lot better.  

      The RS232 is often susceptible to noise. You'll have to run the cable thru the back panel still if you want the Altair cover back on. The ground problem might be caused if the chassis ground [pin.1] on the DB25 connector isn't connected internally to the chassis frame of the system--this is where the noise problem that I mentioned might be coming from. Also have to check again if the internal cable shield is properly connected to the signal ground on the connector [pin.7]


      I also found in the Altair BASIC manual a better explanation of the bootstrap loader (Appendix page 
      99), which helped give me more confidence that I was toggling in the 
      correct instructions before downloading the "papertape" from my laptop.  
      You have to be sure that you have your 2SIO card wired correctly.  The 
      other thing to remember, should anyone here try the same thing is that 
      you have to remember to change the terminal from 8N1 to 7N1 after you 
      download a program.  If I change the jumpers on my 2SIO from 8n1 to 7n1 
      then I can bypass having to change the terminal each time I load a program.
      
        


      On the 2SIO , you can change the bits setting in the code, the baudrate is changed with the jumpers. On the SIO, you can change all of this with jumpers.

      Now we have to try it with the 8K Basic download :)

      =Dan
    • B Degnan
      ... I will check the cable over carefully. I know it s wired correctly, but I did not check the overall grounding or shielding. It s a bare connector at this
      Message 2 of 3 , May 12, 2010
        >> I hung the cable over the chassis rather than through a port in the back
        >> of the chassis, and it worked a lot better.
        >
        > The RS232 is often susceptible to noise. You'll have to run the cable
        > thru the back panel still if you want the Altair cover back on. The
        > ground problem might be caused if the chassis ground [pin.1] on the
        > DB25 connector isn't connected internally to the chassis frame of the
        > system--this is where the noise problem that I mentioned might be
        > coming from. Also have to check again if the internal cable shield is
        > properly connected to the signal ground on the connector [pin.7]
        >
        >
        I will check the cable over carefully. I know it's wired correctly, but
        I did not check the overall grounding or shielding. It's a bare
        connector at this point.

        >> <snip>
        >> change the terminal from 8N1 to 7N1 after you
        >> download a program. If I change the jumpers on my 2SIO from 8n1 to 7n1
        >> then I can bypass having to change the terminal each time I load a program.
        >>
        >>
        > On the 2SIO , you can change the bits setting in the code, the
        > baudrate is changed with the jumpers. On the SIO, you can change all
        > of this with jumpers.
        >
        I will probably do that when I get the chance, but I have a serial
        switch box that I can use as well. One slot for the laptop at 8n1 and
        one slot for a real terminal at 7n1.

        > Now we have to try it with the 8K Basic download :)
        >
        I have already downloaded the image and will try that tonight or asap.
        The directions on the Altiar yahoo group that are stored with the 8K
        BASIC are not very good. I also learned how to change the bootstrap
        code to handle 8K BASIC, the bootstrap loader on solivant.com is set for
        4K BASIC. To kill all birds with one stone, I will scan in the
        appropriate sections of the BASIC Altair manual and annotate them for
        future reference.

        Big Billy Degnopolis
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