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Thread: Anyone here build a Mark-8

  1. Default

    There is some information floating around somewhere that the most significant problem with the Mark-8 was the backplane wiring. If I was to build one, I'd have to go the manually wired backplane route, just to see how bad it might be.

    There is also at least 1 original SCELBI that has a hand wired backplane.

    Mike Willegal

    Quote Originally Posted by Corey986 View Post
    So I'm going to be assembling a vintage Mark-8 where the boards are complete, but were never wired together. They appear to the the boards made from the magazine article. Everything I have found so far seems to be that I just wire the boards together pin to pin straight though each board and there isn't anything tricky like there is to wiring up a similar Scelbi system.

    Can anyone confirm if this is correct? I just can't believe it's that simple.


  2. #12
    Join Date
    Jun 2014
    Salt Lake City, Utah
    Blog Entries


    Quote Originally Posted by Corey986 View Post
    Sure pics are good.

    Hi Corey,

    Pictures posted here:

    I also have a picture of the TTL video card that I designed for my Mark 8. It displays 16 lines by 32 characters. It is I/O addressable on three ports. One to write characters, which advances the cursor. The other two ports set the x/y cursor position.

    Looking from the top it's hard to tell, but every one of my cards has a different offset and the connections do not line up. When I made my back plane I built the offset in so the cards would line up in the case. Otherwise it would have looked really goofy. I bought the boards from a guy off Ebay 15 or so years ago. They were fine except for the offset.

    If you have more questions about the system, or need more pictures, let me know.


  3. #13


    Not all wires go through all boards! There is a gap between the MPX and the ADDR boards. Radio-Electronics failed to publish the "bus" wiring info that identifies the signals, where the signals originate and where they get used, and where the "gap" exists. Send me an email and I'll scan the diagram for you. Do you need any other info? Bob Suding of the Digital Group made some Mark-8 modifications and I can copy this info and mail it to you. Jon Email:


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