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Improvements on existing games?


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#1 vprette OFFLINE  

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Posted Mon Sep 26, 2011 6:53 AM

Hello

my question here is:
is it possible to take on existing original roms, doing debugging / deassembling and modify little code to improve existing games?

like adding a level..
or changing colors or sprite size in space armada to become space invaders?

#2 catsfolly OFFLINE  

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Posted Mon Sep 26, 2011 7:26 AM

In theory it is possible. Joe Zbiciak's jzintv tools include programs that can disassemble existing roms. The disassembled programs can theoretically be modified and reassembled.

The difficulties are:
1. Existing programs use the Intellivision Exec - a program framework built into the Intellivision. The documentation for the exec is not publicly available, so this makes it more difficult to understand and modify existing programs.
2. Decoding and modifying disassembled programs requires different skills than writing new game programs. It is more like detective work.
I don't know if there are people in the Intellivision community who have the interest and skills to do this.

What kind of modifications would you be most interested in?

David

#3 vprette OFFLINE  

vprette

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Posted Mon Sep 26, 2011 7:44 AM

In theory it is possible. Joe Zbiciak's jzintv tools include programs that can disassemble existing roms. The disassembled programs can theoretically be modified and reassembled.

The difficulties are:
1. Existing programs use the Intellivision Exec - a program framework built into the Intellivision. The documentation for the exec is not publicly available, so this makes it more difficult to understand and modify existing programs.
2. Decoding and modifying disassembled programs requires different skills than writing new game programs. It is more like detective work.
I don't know if there are people in the Intellivision community who have the interest and skills to do this.

What kind of modifications would you be most interested in?

David


sorry for my question being trivial:
-what do you obtain after deassembling? is this assembly code o machine language?
-the Exec documentation is property of Intellivision Productions? or it is just lost?

modification would be like new enemies or adding music or change maze maps...
convert pac man to ms. pac man
or centipede to millipede...

or Utopia 2 :-)

Edited by vprette, Mon Sep 26, 2011 8:13 AM.


#4 intvnut OFFLINE  

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Posted Mon Sep 26, 2011 8:51 AM

The EXEC documentation is property of Intellivision Productions. If you look hard enough, you can probably find a copy of "Your Friend the EXEC" out there, but no guarantees. Even if you did find a copy, it may not be all that helpful, because it assumes you've got Mattel's coding environment, header files, etc.

The disassembler gives you a form of assembly code, but it's not significantly better than machine code. The disassembler won't tell you the names or purposes of variables, or give you comments on why the code does what it does. So, as David says above, there's a lot of detective work involved to actually understand the code you're reading.

Certain kinds of modifications are easier than others. Arnauld, for example, has written a program to let you edit Burgertime levels. Other modifications, such as tweaking colors or graphic shapes may be easy in many games. Want to play Baseball with Football player graphics? Go for it! That's likely a hack you could pull off in an afternoon.

More complex or fundamental modifications aren't likely to be easy at all. For example, changing the size of ships in Space Armada: Unlikely to be doable without just rewriting it. A rewrite would be easier. The size of the ships is pretty well baked into how it displays the graphics. You *could* draw smaller pictures for the ships, but they'd still be filling the same grid with the same spacing. I doubt it's the effect you're after.

If someone's truly motivated, they could take apart one of the games and work it to become another game. We've seen this in the Atari 2600 world many times. It *is* a slightly different skill set than just writing a new game from scratch, though. And given that Intellivision Productions is still actively maintaining the copyrights for the original titles, I'm not sure they'd be all that excited to have others hacking their ROMs and distributing the hacks.

#5 DZ-Jay OFFLINE  

DZ-Jay

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Posted Tue Sep 27, 2011 2:47 AM

And not to mention that it is worlds more fun and exciting to re-make a classic game on your own, from scratch.

I can tell you that figuring out how to implement Pac-Man on an Intellivision with just careful observations of the arcade game to me was a lot more satisfying than poring over pages of disassembled code to see how the original programmers did it.

Joe and David are right, it is a different skill set and a different interest altogether. The motivation is curiosity much more than creativity.

-dZ.




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