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Help me get into this guy's mind: 8086 INC/DEC pairs

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  • Scali
    replied
    Originally posted by Trixter View Post
    It would, considering how you managed to fix the graphics without knowing any assembler!
    Yes, I take it they were not compiled sprites then. Because those would be very hard to modify afterwards.
    The modified version looks really great too!
    Reminds me of Burger Time, perhaps one of the best composite CGA arcade ports made.

    Leave a comment:


  • Trixter
    replied
    Originally posted by el_VR View Post
    I thought the name sounded familiar, and indeed - a Dana How (sans "e") worked on the PC port of EA's Hard Hat Mack, "through TMQ Software, Inc". Maybe the different spelling and the TMQ lead would be helpful there.
    Good catch -- Hard Hat Mack has the same kind of transcoding shenanigans going on:

    Code:
    seg000:1249                 mov     al, 79h
    seg000:124B                 inc     al
    seg000:124D                 dec     al
    seg000:124F                 mov     byte_111EF, al
    (Speaking of which, I wonder if a blog entry about my own silly hack would still be interesting)
    It would, considering how you managed to fix the graphics without knowing any assembler!

    Leave a comment:


  • VileR
    replied
    Originally posted by Trixter View Post
    Steve Hays, who wrote the Apple II version, got in contact with me and told me the person who did the trans-compilation system was Dana Howe. Hopefully I can get in contact with them and can report back.
    I thought the name sounded familiar, and indeed - a Dana How (sans "e") worked on the PC port of EA's Hard Hat Mack, "through TMQ Software, Inc". Maybe the different spelling and the TMQ lead would be helpful there.

    (Speaking of which, I wonder if a blog entry about my own silly hack would still be interesting)

    Leave a comment:


  • per
    replied
    Originally posted by Chuck(G) View Post
    So the INC/DEC on AL when CL is loaded at 5E18 is an error? And the author didn't notice it?
    CL is being loaded with AL, so it's the same value anyways. It's not clean, but it still works as intended.

    Leave a comment:


  • Chuck(G)
    replied
    My guess is that the first version of the transcompiler/macro set didn't do the INC/DEC thing and the game didn't work. The addition of the INC/DEC was done as a shotgun-style "Hail Mary" maneuver and probably with a manager breathing delivery schedules down the neck of the poor programmer.

    Leave a comment:


  • Scali
    replied
    Originally posted by Chuck(G) View Post
    So the INC/DEC on AL when CL is loaded at 5E18 is an error? And the author didn't notice it?
    Could be... The 6502 only has one accumulator, so perhaps they didn't think of that when writing the transcompiler. What is interesting though is that it would actually use cl in that case... So they did think of that
    Weird.

    Leave a comment:


  • Chuck(G)
    replied
    Originally posted by Trixter View Post
    The PC version was transcompiled; what you're seeing is an error in the transcompilation.
    Exactly my point. If it's a transcompilation, the error must have occurred again and again in the process. And apparently with no bad effect.

    Leave a comment:


  • Trixter
    replied
    The PC version was transcompiled; what you're seeing is an error in the transcompilation.

    Leave a comment:


  • Chuck(G)
    replied
    So the INC/DEC on AL when CL is loaded at 5E18 is an error? And the author didn't notice it?

    Leave a comment:


  • Scali
    replied
    Originally posted by per View Post
    And 6502 does indeed set Zero and Sign flags on register load.
    Yes, that might explain it... It seems to emit the inc/dec sequence after every mov reg, mem operation.
    Apparently that code was 'good enough'... even though the translation is probably slower than on a real 6502.
    Otherwise I guess they would have made the translator just a bit more clever, and only emit the sequence when a following instruction actually looks at the flags, rather than just overwrite them.

    Leave a comment:


  • Trixter
    replied
    Steve Hays, who wrote the Apple II version, got in contact with me and told me the person who did the trans-compilation system was Dana Howe. Hopefully I can get in contact with them and can report back.

    Leave a comment:


  • per
    replied
    And 6502 does indeed set Zero and Sign flags on register load.

    Leave a comment:


  • Trixter
    replied
    Originally posted by reenigne View Post
    Hmm... Atari ports of arcade games circa 1983... You could try asking this guy. He worked on 2600 ports rather than PC ports so it's kind of a long shot but he might have some insight or a contact for the next step on the trail.

    Edit: Oh wow, there are even some anecdotes about Robotron on that page, and a comment from the author of Apple II Robotron.
    Holy crap, and this: "I went on to do Ms. Pacman, also for the Apple – and my code for both games was trans-compiled for the PC." I think we have a winner! I'll try to contact him.

    Leave a comment:


  • Trixter
    replied
    Originally posted by Scali View Post
    Not really, notice the nasty inc di after the movsb.
    I would have stored the string with its attribute bytes, personally.

    Even if you do find them, I doubt they'll ever admit to it
    Actually, that attitude is changing. 30+ years onward, people are happy to be interviewed (there are some great interviews done by the Antic podcast with a lot of behind-the-scenes gems) and others are happy to share source code.

    Leave a comment:


  • reenigne
    replied
    Originally posted by Trixter View Post
    I wish there was any indication at all of who ported the game, but there aren't any identifying strings on the disk, and the original packaging/label/manual/warranty/registration card don't have any developer information other than "manufactured by ATARI". This was 32 years ago; I have no idea how to even begin trying to track down who programmed this.
    Hmm... Atari ports of arcade games circa 1983... You could try asking this guy. He worked on 2600 ports rather than PC ports so it's kind of a long shot but he might have some insight or a contact for the next step on the trail.

    Edit: Oh wow, there are even some anecdotes about Robotron on that page, and a comment from the author of Apple II Robotron.
    Last edited by reenigne; June 5, 2015, 03:54 AM.

    Leave a comment:

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