Atari - Millipede Disassembly

[DEBRO]

Hi there,

 

As the title says this is the Atari version of Millipede reverse-engineered. The masterpiece done by Dave Staugas and the one we got on cart in 1984. Hopefully I got this some what correct. There is A LOT going on in this 16K ROM.

 

I left the graphics data in the code just as the ROM would need it. Sorry to the graphic hackers, but I didn't take the time to make it "easy" to hack the graphics.

 

If you are interested in changing the graphics then know they are interleaved. They are separated in the code by their scanline or zone similar to how 7800 graphics are defined. You can find the appropriate graphic number by using the ID_ constants. For example, the second and third graphic data items in their corresponding zone would represent the 2 animations for the Bee, the 4th through the 7th graphic data items in their corresponding zone would represent the 3 animations for the Earwig, and so on.

 

There is a scoring bug in the code. When hitting a Millipede segment with the DDT cloud you score 3X the "head points" and when a Millipede head is hit with a DDT cloud you receive 3X the "body segment points". You can see this in the CheckCloudCollisionWithMillipede routine. Dave mistakenly uses D7 high of the segment state to think that meant a Millipede head segment. Instead, having the state value high means the item is a Millipede body segment.

 

I've including switches to build NTSC, PAL50, and PAL60 versions. There is also a switch to easily build a trainer or cheat ROM that removes all deadly touches (i.e. play forever).

 

Hopefully, I'll get back on the GCC prototype version one day. I was making great progress on it with this and Centipede done.

 

It is interesting how bit masks for the Atari Millipede are similar to the GCC version. From an interview done by Into The Vertical Blank: Lost Credits (HD): The Secret Atari Heroes of GCC (full version) GCC says they would have started their conversion before Dave would have started his for Atari. Maybe they're similar because both used Centipede as a starting point? GCC would have had the original source code to Centipede since they developed it. Would they had given or shared the source code with Atari? Did Dave or people from Atari reverse-engineer it before Dave did his Millipede? I wonder...

 

Enjoy

Atari - Millipede