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Game Alteration and Programming.


CV Gus
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HELP!

 

 

So far, within the past 1 1/2 weeks, I've finally managed to get the Virtual ColecoVision to work- it plays most games.

 

I downloaded some CV tools, and today managed to finally get the compiler CC13.EXE in the CVDEVKIT_BUILD_20130720 working well enough to compile some of the test programs, but not the "Rebound" program in the CV PROGRAMMING PDF file- maybe copying and pasting it won't work, but at least nothing crashed, all I got was a black screen.

 

But if someone wants to alter a ROM game file, how would one go about it? What do you use to read it? A Hex Editor seems a bit klutzy, how do you find locations for determining what sprites look like, adding a sprite, that sort of thing? Daniel Bienvenu's video helped a little, but I need a place to start.

 

Thanks.

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If you want 'alter' existing game. I don't think the C Devkit will help you a lot.

 

To alter game, you can use an hexadecimal editor . But to know what byte to change it is another issue....

 

You have some tool i think that could help you to detect where are Graphism and sound (to a certain limit). you can do also yourself tool to detect graphick patterns. One tricks that works sometime if just to display the ROm file as an image. (where each bit at 1 is a pixel ) , that way you can sometime see where are the sprites and the pattern (if they are not compressed).

 

then if you want alter behavoir of the game , you have to debug the game with a debugger (like the one included in BlueMSX) to find where is the code you want to change. Then you can change it (after having converted to bytes ) with the Hex Editor.

 

The other way , if you want do big changes , is to dissassamble the rom to have a assembler source file, modify the code and reassemble.

but have have to have assembler skill for that.

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If you want 'alter' existing game. I don't think the C Devkit will help you a lot.

 

To alter game, you can use an hexadecimal editor . But to know what byte to change it is another issue....

 

You have some tool i think that could help you to detect where are Graphism and sound (to a certain limit). you can do also yourself tool to detect graphick patterns. One tricks that works sometime if just to display the ROm file as an image. (where each bit at 1 is a pixel ) , that way you can sometime see where are the sprites and the pattern (if they are not compressed).

 

then if you want alter behavoir of the game , you have to debug the game with a debugger (like the one included in BlueMSX) to find where is the code you want to change. Then you can change it (after having converted to bytes ) with the Hex Editor.

 

The other way , if you want do big changes , is to dissassamble the rom to have a assembler source file, modify the code and reassemble.

but have have to have assembler skill for that.

 

 

How do you use the debugger in BlueMSX? I have to put it in CV mode to get the ROMs to work, and when I try to use the debugger, I'm told that "Disassembly Unavailable."

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Press the "pause" button, and the code will appear, then you can do step by step run.

 

 

 

 

 

Thanks for the reply!

 

I stumbled across that later that night...

 

Right now I have two medical emergencies in the family to deal with, so I cannot be out very often or for any length of time. Therefore if something isn't obvious I have to ask about it when I can and hope an answer (if I haven't figured it out) will be there the next time. My posts may well be "out of sync" for those reasons.

 

The instructions claim you can alter the code directly but although the indentation appears the hexadecimal number always reverts back to the original. How do you deal with that?

 

And is there anywhere one can find any instructions on coding? It is a bit- just a bit- like Javascript, but not nearly enough.

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If you are used to programming in Javascript, then you probably want to go with the C programming route.

 

First: https://archive.org/details/the_c_programming_language_2

That'll get you the best book on the language, written by Ritchie himself.

 

Then go to youtube and look up "NewColeco", it'll give you all his tutorials.

 

I'm assuming you are running Windows and have installed the utilities already.

 

Personally, I'm trying to do this with assembler, and I'm following the youtube videos by "ElectricAdventures". Good stuff.

 

Sorry if this wasn't helpful, I'm finding I miss the point a lot lately ;)

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Although it's mostly guesswork with things like the color code, here is what I've managed so far:

 

(See images)

 

 

None of the literature I've downloaded explains things like where numbers are stored, so I do not even know how to change screen modes, let alone how to get better-looking images for Centipede in Mode 2, which would need more numbers for a given character! Since Centipede is in Mode 0, this is the best I can do so far.

 

And forget at this time adding a sprite to make Mr. Do! or your gun in Centipede multi-colored. But keep in mind I only really started just yesterday, and the problems here are very distracting.

post-11032-0-43137000-1473622844_thumb.png

post-11032-0-47229600-1473622855_thumb.png

post-11032-0-36320500-1473622870_thumb.png

Edited by CV Gus
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