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Thread: Color Computer EPROM problem

  1. #1
    Join Date
    May 2006
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    Hamilton, Ontario, Canada
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    Default Color Computer EPROM problem

    Hi,

    I'm having a problem with burning a diagnostic EPROM (2.0) from a .ccc that perhaps someone could help me with.
    I have the file and I converted it to a .bin file using Joe Strosnider's CCC-TO-BIN program.
    When I load it into the TL-866CS buffer, it looks good and I can see the ASCII parts of the menu and it burns to a 2732A EPROM without any apparent problem.
    I put it into a cartridge containing one of NF6X's CoCoEPROMPak boards, in the 24 pin socket section, put on the auto-start jumper and plug it into a Color Computer.
    What I get is a green screen with black lettering on the first line as below;

    R Diagnostics ROR (with the word centered in the top line, the single R on the left of the line and the ROR about 6 spaces to the right of the word).

    That's it.
    I'm guessing that it's, possibly, trying to make me aware of an error.
    I have tried several ROMs in a color basic CoCo 1 and two Extended color basic CoCo 2s (I haven't tried in in a CoCo 3 because I don't even know if it would work in it).
    Can anyone spot what I might be doing wrong or offer some guidance?

    TIA
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  2. #2
    Join Date
    May 2006
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    Default

    I forgot to mention that the program is only 2K in length.
    Would I have to join two copies together and burn it or set start and end addresses?
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  3. #3

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    I suspect it is because you are using the wrong part. Looking at the schematic, you are suppose to use a 24 pin 8Kx8 part. Without an adapter you are not even matching the address pins. Also, if this is to be a boot, I believe it needs to load in the high part of the EPROM, not at address 0.
    Ops, I see you have some type of adapter.
    I guess the question is what address do you expect it to run at?
    Dwight

  4. #4

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    My guess is that you have to put the code at the higher half of the EPROM.
    Dwight

  5. #5
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    Default

    Thank you Dwight.
    Yes, I am using a board designed by NF6X on the forums here for use with more current EPROMs in the Color Computer.
    I will have to read up on where the computer expects the cartridge ROM to be located.
    This is not really my forte, so I'll have to figure it out.
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  6. #6
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    Default

    Thanks to NF6X, we were able to figure out the problem and the cartridge works.
    On the down-side, it will only test 16K of memory...Sigh.
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  7. #7

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    Quote Originally Posted by Druid6900 View Post
    Thanks to NF6X, we were able to figure out the problem and the cartridge works.
    On the down-side, it will only test 16K of memory...Sigh.
    I'm having the exact same problem with the CoCoEPROMpak I built today. In fact, of the 20 to 30 .ccc files I've converted and .bin files I've downloaded, only two of them work properly. The rest either display garbage, or only partially work. I get the same "R Diagnostics ROR" that you were before. Can you share what the solution you found to the problem was? I've spent hours burning and testing today and haven't gotten very far!

  8. #8
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    IIRC, the conversion programs were adding some code at the beginning of the .BIN file that was causing the problem(s).
    I also seem to recall that the reason for this was so it would work with emulators.
    You would have to talk to NF6X about it as he was the software Whiz in this operation.
    Me, I'm just an ol' country electronic brain surgeon..
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  9. #9

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    Quote Originally Posted by Druid6900 View Post
    IIRC, the conversion programs were adding some code at the beginning of the .BIN file that was causing the problem(s).
    I also seem to recall that the reason for this was so it would work with emulators.
    You would have to talk to NF6X about it as he was the software Whiz in this operation.
    Me, I'm just an ol' country electronic brain surgeon..
    Thanks for your quick reply! Believe it or not, that's all I needed to get things working! For anyone else who runs into this in the future, here is the one-line change to make to the ccc-to-bin script so it emits .bin files that work when written to eeprom:

    < $final = $preamble + $source + $postamble

    > $final = $source

    Thanks again!

  10. #10
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    Default

    My Pleasure.
    What converter were you using?
    BTW, it turns out that the CoCo Diagnostic V2 WILL test up to 64K of RAM in the 1 and 2.
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

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