(Topic ID: 169522)

WPC EPROM & ROM File sizes

By ForceFlow

7 years ago


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  • 30 posts
  • 12 Pinsiders participating
  • Latest reply 5 years ago by barakandl
  • Topic is favorited by 8 Pinsiders

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    #3 7 years ago

    Standard practice is to double it up so the entire ROM is filled with data and nothing random. This would eliminate any potential floating data/address lines from jumping to portions of code with garbage in them.

    #5 7 years ago
    Quoted from Brtlkat:

    A 27c080 is an 8MB chip.

    8 megabits is 1 megabyte. A 128KB file will fit into that chip 8 times.

    #8 7 years ago

    Oops I didn't mean to post this. Anyways let me know if you have any further questions.

    #14 7 years ago
    Quoted from ForceFlow:

    Yeah, I wasn't able to find anything explicitly written about it for WPC, which is why I'm asking.

    If you aren't sure if it's required for a particular board (WPC in this case) it should always work by doubling or copying the image as needed to fill the EPROM. Some boards may have the unused lines tied (to either ground or +5V, I forget which) and then wouldn't need the image copied over. Some boards leave these unused lines floating and that's when you really need the additional rom space filled so it doesn't float to a garbage block, it just floats to another region with the exact same data and thus sees no change.

    In short, it never hurts and you will always be safe by filling up the EPROM.

    #20 7 years ago
    Quoted from zacaj:

    As long as it's a size that's used by that board is any game, shouldn't it be fine without doubling up?

    Yes. Doulbing or quadrupling, etc. only applies when using a larger than necessary eprom that shares the same pinout as the intended smaller size eprom.

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