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6800 to 6809 adapter needed

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    6800 to 6809 adapter needed

    Hello,

    I own a Eurocom-1 computer equipped with a 6802 CPU. A Dutch book mentions a small adapter with a 6809 on it that you plug in the place of the 6802.
    My questions:
    - Does anybody know where I could get such an adapter?
    - Does anybody know a schematic so I could build one myself?

    Many thanks in advance!
    With kind regards / met vriendelijke groet, Ruud Baltissen

    www.baltissen.org

    #2
    Originally posted by Ruud View Post
    Hello,

    I own a Eurocom-1 computer equipped with a 6802 CPU. A Dutch book mentions a small adapter with a 6809 on it that you plug in the place of the 6802.
    My questions:
    - Does anybody know where I could get such an adapter?
    - Does anybody know a schematic so I could build one myself?

    Many thanks in advance!
    I have one, I'm not selling it but let me see if I can reverse engineer it and post schematics

    Comment


      #3
      I have one of those boards for a MEK6802D5 board I have. I don't have it running but the boards contains a 6809, a 74163, 74LS08, a 74175, a 74LS00, a 74LS04, 74LS74. I'll need to reverse engineer the board and post the schematic. It's a single sided board with about 10 jumper wires. The board is from about 1985.

      Comment


        #4
        Originally posted by ncherry View Post
        I have one of those boards for a MEK6802D5 board I have. I don't have it running but the boards contains a 6809, a 74163, 74LS08, a 74175, a 74LS00, a 74LS04, 74LS74. I'll need to reverse engineer the board and post the schematic. It's a single sided board with about 10 jumper wires. The board is from about 1985.
        Just out of curiosity, I had a look at the MC6802 datasheet. It has some built-in RAM (128 bytes if I'm not mistaken), I thought it would be easy to come out with an adapter schematic if it was really impossible to find an original one. It seems to me anyway that a general purpose replacement board should contain at least that small amount of RAM. The chips you mentioned are only general purpose logic, so it might work in a place where the internal 6802 RAM is not used. However, I might be mistaken of course.
        Best regards
        Frank IZ8DWF

        Comment


          #5
          Frank you are correct, if the board for the 6802 has no ram then the 6809 will have some trouble running (it's possible to write code that doesn't use ram but I won't do it ).

          I've got pictures of the board and I'll upload them to my site and provide a link here. The pictures are large and I doubt I have permissions to post links yet (new user, less than 10 posts).

          Comment


            #6
            Hi Ruud, not a schematic yet but huge pictures:

            Component side:
            http://ushomeautomation.com/Projects...604_115916.jpg

            Copper side:
            http://ushomeautomation.com/Projects...604_115828.jpg

            This board dates back to the 80's and it's still clean, wow.

            Comment


              #7
              Originally posted by ncherry View Post
              Frank you are correct, if the board for the 6802 has no ram then the 6809 will have some trouble running (it's possible to write code that doesn't use ram but I won't do it ).

              I've got pictures of the board and I'll upload them to my site and provide a link here. The pictures are large and I doubt I have permissions to post links yet (new user, less than 10 posts).
              I just had a look at the Euro 1 and I now see how Frank comments relate. He is correct the 6809 has no RAM internally. So you'll need to add RAM and the decoding for it. Also the 6802 ROM code won't run on the 6809. So it's not a drop in replacement.

              Comment


                #8
                This would be something I am interested in as well. Is anyone going to look at knocking out a designing based on above screenshots and putting it on somewhere like oshpark? Or is this something I will have to look at doing when I have a free slot in my todo list (somewhere in the next 10 years).

                Comment


                  #9
                  Oh, sorry forgot to add this. I seem to recall this design coming from an EE magazine. I recall seeing the article. I am finding it really odd the I can find that information in a search of the internet.

                  Comment


                    #10
                    Hallo ncherry,

                    I'm looking forward to the schematic!
                    With kind regards / met vriendelijke groet, Ruud Baltissen

                    www.baltissen.org

                    Comment


                      #11
                      Originally posted by ncherry View Post
                      I just had a look at the Euro 1 and I now see how Frank comments relate. He is correct the 6809 has no RAM internally. So you'll need to add RAM and the decoding for it. Also the 6802 ROM code won't run on the 6809. So it's not a drop in replacement.
                      But the Eurocom has 1 KB RAM of its own starting from $0000. The lower RAM isn't used because the 6802 will use its internal RAM. The PCB on the picture in the book is very small. IMHO it is just a 6809 plus maybe two IC under it, certainly no extra RAM.
                      With kind regards / met vriendelijke groet, Ruud Baltissen

                      www.baltissen.org

                      Comment


                        #12
                        I used to have a Motorola D2 kit. It used a 6800 processor. I eventually modified it to use a 6809 processor and rewrote the monitor software to work with the 6809 and handle the extra registers it has. The board I designed and built to allow a 6809 to plug-in to the 6800 socket used only 2 diodes, 2 resistors, and a transistor. I no longer have my D2 kit but I remembered the diodes were an OR gate and the transistor was an inverter. I went over the datasheets for the 6800 and 6809 and have worked out what I had done before. I've drawn up a(n untested) schematic for it. I also looked at how to plug a 6809 in to a 6802 socket and worked up schematic for it as well. The only catch is that the simple 6802 to 6809 mod doesn't include memory. If any one is still interested in using a 6809 in place of either a 6800 or 6802 I could made the schematics available.

                        Comment


                          #13
                          Originally posted by Kevin C. View Post
                          If any one is still interested in using a 6809 in place of either a 6800 or 6802 I could made the schematics available.
                          I am interested!
                          With kind regards / met vriendelijke groet, Ruud Baltissen

                          www.baltissen.org

                          Comment


                            #14
                            I have posted my 6800 and 6802 to 6809 adapter circuits to my website. The URL for the page with links to schematics is 680x to 6809 adapters.

                            Comment


                              #15
                              Thank you very much!
                              With kind regards / met vriendelijke groet, Ruud Baltissen

                              www.baltissen.org

                              Comment

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