Would Appreciate A Tutorial on HexEdit

  • Bill Strohm

    Bill Strohm - 2009-08-27

    I have tried using HexEdit in pursuit of a problem with an old video game (LucasArt's "The Dig") that sometimes runs properly and sometimes does not, under Classic supplied with Mac OS X 10.4.11 on my PPC G5. Looking at the main program's DATA and RSRC screens in HexEdit, I can find groups of text, which act like commands, and large areas of nonsense, which presumably are not nonsense. I am not a programmer (except once long ago in Basic and APL), just a user. After making various duplicates of the program and playing with them, I have concluded that the program is (usually) failing to "Capture the display" (as Apple puts it). Opening the program runs the audio portion and affects the colors of my monitor, varying by scene, but the display is of the OS X DeskPicture instead of the game graphics. I am also making a wild guess that the "DrawSprocket" extension in the Classic System Folder is somehow not always able to connect properly to Mac OS X to display the program screen, although sometimes it does.

    Sorry to ramble, but I thought if I understood what I was looking at in the "Disassemble PPC Code" screens of HexEdit, I might be able to make some progress. Unfortunately those displays, both DATA and RSRC, make even less sense to me than the standard screens. I cannot find any references to a tutorial or any links to an explanation of the meanings of HexEdit's displays. I do understand that on the standard screens the left side columns are the ASCII equivalent of the right column's text, and have seen how changing the text changes the commands, but that's about it.

    Any help for an old guy who would like to play an old Classic game consistently? I have already reinstalled the game, OS X, OS Classic, tried other sources for Classic extensions, run all my Apple and 3rd-party OS X utilities, etc. Everything comes back "passed."

    But mainly I want to understand where those commands in the HexEdit DATA file actually go!

  • Lane Roathe

    Lane Roathe - 2009-09-15

    The DATA and RSRC displays are showing you the raw data of the data and
    resource forks of the file, respectively.

    The information they display will only make as much sense as the data in those
    forks, in this case it will be pretty much meaningless.

    So, when you are looking at the DATA view, you are not actually looking at
    commands, you are viewing information in the data resource of whichever file
    you have open. These may look like commands, but they are not. (Thus the lack
    of documentation, because what you see will vary based on the file you choose
    to open, it's different every time.)

    Editing a program in this fashion is an extremely advanced topic, and requires
    a very good understanding of PowerPC assembly language and machine code.

  • Bill Strohm

    Bill Strohm - 2009-09-15

    Thanks for your response. I later discovered a trick to make the program work,
    without involving HexEdit. I do appreciate your reply; it looks like I will
    never be qualified to use HexEdit... no problem now, though.


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