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Colors, colors, colors


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Hi, I need some help for changing colors in RiverRaid and Defender II. Without help I can't do it because disassembling and reassembling is to difficult for me, yet. I want new playfield and sprite colors in RiverRaid and a new ship color in Defender II. Any help???


(RiverRaid graphics are weired coded. It's difficult to change something more than the own plane. What's the trick?)

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IIRC, River Raid uses interlaced graphics...so you would need to study the disassembly to see how those sprites are reconstructed by the program (i.e. the data is not in a straight line). Here's a VERY rough disassembly with a config file. Keep in mind that until jump points are identified, you should refrain from altering the number of bytes used in any area...and if you delete program code, fill up the "hole" it creates by using NOP instructions.


Defender II is an 8k game, so the binary would need to be split in half first by using a filesplitter (like the free programs MasterSplitter or HJsplit)...and THEN disassembled (also using .cfg files to identify where program and data exist).


To change colors, what you would be looking for in the program is values that are saved to the COLUP0 and COLUP1 registers. If these values are coming from another ram address, you need to backtrack and search the program for areas that values are saved to those addresses.


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...and here's Defender II (again, a VERY rough disassembly). This zip includes the .cfg files as well as the split binary. If you want to edit it an re-assemble, you need to do both halves seperately using Dasm, and then join the files together (either by using the aforementioned splitting programs or by using the Dos COPY command including the /b switch...like this...




...that would create the file called D2HACK.BIN from the two halves.


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If I don't dis- and reassemble Defender II why is it broken if I only change one bit in the graphics with hack-o-matic?


And - is anybody able to say, if I could change the ship color without changing the background color (both are red) without reading the disassembly 2 weeks?

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Probably the same reason that other hacks won't run on emulators...the emulator can't identify it to determine what bankswitching scheme is being used after it runs a checksum (changing even one byte would effect the checksum). So you need to use Z26 and "force" the emulator to use a certian scheme. Use -g2 as part of the command line.


Also, keep in mind that the bitmaps shown in the disassemblies are just comments (ignored by the assembler). Just changing the placement of the X's in those lines will have no effect whatsoever.



BTW here's a puzzler...


That page states that DefenderII/Stargate uses 16k, but both the roms here are only 8k :?

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