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Re: VP620 VIP ASCII Keyboard Interface

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  • ekeefe8051
    Hello, You are welcome. If you need me to check anything on my actual hardware, just ask. ED
    Message 1 of 9 , Feb 12, 2013
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      Hello,

      You are welcome.

      If you need me to check anything on my actual hardware, just ask.

      ED

      --- In rcacosmac@yahoogroups.com, "Bill Dromgoole" wrote:
      >
      > Thank you, thank you, thank you!
      > That is exactly what I needed.
      >
      > I had already read your VIP II write up twice.
      > I appreciate a man on a mission.
      > I couldn't believe how much work you did on that project.
      > I even enlarged some of your photos of the extender boards you made to get the Sullens part numbers of the male connectors.
      > Digi-Key has them in stock. I was planning on making a set for myself.
      >
      > It looks like you have every cosmac manual known to man.
      > Next time I need information I'll know who to ask.
      > I'll keep you informed of my progress on the keyboard.
      >
      > Thanks again,
      > billdrom
      >
      >
      > ----- Original Message -----
      > From: ekeefe8051
      > To: rcacosmac@yahoogroups.com
      > Sent: Tuesday, February 12, 2013 11:20 AM
      > Subject: [rcacosmac] Re: VP620 VIP ASCII Keyboard Interface
      >
      >
      >
      > Hello,
      >
      > That cover is from the gallery on my COSMAC VIP site:
      >
      > www.cosmacvip.com
      >
      > Here are the 4 pages of the keyboard document:
      >
      > http://www.avionline.com/rca_keyboards/VP601-VP611-1.JPG
      > http://www.avionline.com/rca_keyboards/VP601-VP611-2.JPG
      > http://www.avionline.com/rca_keyboards/VP601-VP611-3.JPG
      > http://www.avionline.com/rca_keyboards/VP601-VP611-4.JPG
      >
      > Please let me know how you make out.
      >
      > If you have time, please check out my COSMAC VIP II write-up at: http://www.cosmacvip.com/VIP2/VIP2.php
      >
      > I'm curious what people think about that project.
      >
      > ED
      >
    • Bill Dromgoole
      I have continued working on the VP611 keyboard now that I have the full schematic thanks to Ed. A very similar keyboard scanning circuit is in the CMOS
      Message 2 of 9 , Feb 19, 2013
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        I have continued working on the VP611 keyboard now that I have the full schematic thanks to Ed.
        A very similar keyboard scanning circuit is in the CMOS Cookbook by Don Lancaster.
         
        After disconnecting the three ribbon cables from the membrane keyboard assembly from the scanning electronics circuit board the audio signal stopped.
        First I used a scope to verify the oscillator was running and the 4051 scan outputs were all correct and they were.
        Next I used a short piece of wire to short each row scan to each column scan line with the interface connected to the computer and the Tiny Basic card installed.
        I was able to generate every alphabetic and numeric character on the monitor screen.
        This shows that the input port on the computer is OK and the scanning electronics is working properly.
         
        Next I tried to test each switch on the keyboard with an ohmmeter at the ribbon cable ends.
        The numeric pad on the right side tested ok but all the switches on the rest of the keyboard appear to be shorted. Even the two isolated keys user 1 and 2 .
        I really find it hard to believe that every thing is shorted. There doesn't appear to be much hope of fully repairing the keyboard at this point.
        I don't know if I can remove the membrane from the aluminum back panel or not.
         
        But then again what is there to lose. Although it does look ok for display purposes as it is.
         
        Bill
         
        ----- Original Message -----
        From: billdrom
        Sent: Monday, February 11, 2013 12:38 PM
        Subject: [rcacosmac] VP620 VIP ASCII Keyboard Interface

         

        I am trying to get my VP611 ASCII keyboard working with my VP711 COSMAC and VP700 tiny basic board. So far no luck. When I plug in the keyboard and interface I get the Q light and tone from the VP711 and the tone from the VP611. I do get the Ready prompt on the monitor but none of the keys function. I'm guessing that I have a stuck bit somewhere that is telling the computer there is a key pressed. I can't find any info on line, so I started to analyze the circuit myself.
        Step one was to figure out the connections from the keyboard to the computer. I posted an album in the photos section with the Adapter interface in case anyone wants to build their own.If someone has a scan of the keyboard manual, interface manual or tiny basic manual I would like to look at it. Maybe I am doing something wrong, like missing a jumper.

        billdrom

      • ekeefe8051
        Hello, Did you check to see if any of the scan columns or rows are shorted to the aluminum back plate? Maybe only one character has worn through. Check to see
        Message 3 of 9 , Feb 20, 2013
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          Hello,

          Did you check to see if any of the scan columns or rows are shorted to the aluminum back plate? Maybe only one character has worn through. Check to see if the ribbon cable itself is shorted as it goes through the aluminum plate.

          I tried to repurpose one of the RCA keyboards to use just the case, and I can say from experience that you will destroy the keyboard membrane if you try to pull it off. But as you said, what do you have to lose.

          Have you considered rewiring an old PC keyboard? A lot of cuts and jumps but it can be done.

          ED

          --- In rcacosmac@yahoogroups.com, "Bill Dromgoole" <billy.boyo@...> wrote:
          >
          > I have continued working on the VP611 keyboard now that I have the full schematic thanks to Ed.
          > A very similar keyboard scanning circuit is in the CMOS Cookbook by Don Lancaster.
          >
          > After disconnecting the three ribbon cables from the membrane keyboard assembly from the scanning electronics circuit board the audio signal stopped.
          > First I used a scope to verify the oscillator was running and the 4051 scan outputs were all correct and they were.
          > Next I used a short piece of wire to short each row scan to each column scan line with the interface connected to the computer and the Tiny Basic card installed.
          > I was able to generate every alphabetic and numeric character on the monitor screen.
          > This shows that the input port on the computer is OK and the scanning electronics is working properly.
          >
          > Next I tried to test each switch on the keyboard with an ohmmeter at the ribbon cable ends.
          > The numeric pad on the right side tested ok but all the switches on the rest of the keyboard appear to be shorted. Even the two isolated keys user 1 and 2 .
          > I really find it hard to believe that every thing is shorted. There doesn't appear to be much hope of fully repairing the keyboard at this point.
          > I don't know if I can remove the membrane from the aluminum back panel or not.
          >
          > But then again what is there to lose. Although it does look ok for display purposes as it is.
          >
          > Bill
          >
          > ----- Original Message -----
          > From: billdrom
          > To: rcacosmac@yahoogroups.com
          > Sent: Monday, February 11, 2013 12:38 PM
          > Subject: [rcacosmac] VP620 VIP ASCII Keyboard Interface
          >
          >
          >
          > I am trying to get my VP611 ASCII keyboard working with my VP711 COSMAC and VP700 tiny basic board. So far no luck. When I plug in the keyboard and interface I get the Q light and tone from the VP711 and the tone from the VP611. I do get the Ready prompt on the monitor but none of the keys function. I'm guessing that I have a stuck bit somewhere that is telling the computer there is a key pressed. I can't find any info on line, so I started to analyze the circuit myself.
          > Step one was to figure out the connections from the keyboard to the computer. I posted an album in the photos section with the Adapter interface in case anyone wants to build their own.If someone has a scan of the keyboard manual, interface manual or tiny basic manual I would like to look at it. Maybe I am doing something wrong, like missing a jumper.
          >
          > billdrom
          >
        • Bill Dromgoole
          I have a couple of unencoded keyboards I could use but the ultimate goal was to have an original RCA keyboard to match the computer. I did not check to see if
          Message 4 of 9 , Feb 20, 2013
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            I have a couple of unencoded keyboards I could use but the ultimate goal was to have an original RCA keyboard to match the  computer.
            I did not check to see if anything was shorted to the aluminum plate. I'll do that.
            There is a company that still makes a similar keyboard. Maybe they have parts available.
             
             
            We'll see.
             
            Bill
             
             
             
             
             
             
            ----- Original Message -----
            Sent: Wednesday, February 20, 2013 8:02 AM
            Subject: [rcacosmac] Re: VP620 VIP ASCII Keyboard Interface

             

            Hello,

            Did you check to see if any of the scan columns or rows are shorted to the aluminum back plate? Maybe only one character has worn through. Check to see if the ribbon cable itself is shorted as it goes through the aluminum plate.

            I tried to repurpose one of the RCA keyboards to use just the case, and I can say from experience that you will destroy the keyboard membrane if you try to pull it off. But as you said, what do you have to lose.

            Have you considered rewiring an old PC keyboard? A lot of cuts and jumps but it can be done.

            ED

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