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Football disassembly


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Hi there,


Attached is my first attempt at reverse engineering a game by Bob Whitehead. Bob Whitehead is credited for creating the six digit display kernel as well as the venetian blinds technique.


I've read most don't consider this a proper football game and consider it a bad VCS game. Keep in mind this was released in 1979...before the Intellivision released their NFL Football game. Also, this was done when ROM cost was more expensive. He produced what I consider to be a good representation of the game in 2K of ROM and using 108 bytes of RAM. I remember playing this game with a neighbor that had it and we enjoyed every minute.


This listing includes the NTSC version and the PAL50 version that was present on the 32 in 1 cart. The PAL50 version only changed the frame timings for vertical blanking and overscan. All the colors stayed the same as the NTSC version so the colors don't look correct for PAL50. I assume this wasn't a game played in a PAL region being this is considered American Football.


I want to thank @Andrew Davie for the INTERLEAVED_GRAPHICS macro in this listing. The graphics for the play indicator are interleaved and the graphics for the offensive indicator are interleaved. This macro was used or created to hopefully allow you to see the true graphics for these sprites.


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Thanks, Dennis!


Did you find structures or algorithms in the code that you didn't see before? E.g. those interleaved graphics?

And the six digit display is an amazing clever 'trick', so hats off to Bob!


I wonder why they didn't bother to change the colors for the PAL50 version of Football. Having a blue football pitch for sure didn't help to make Football more popular in Europe ? 

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Hi there,


On 12/30/2019 at 3:24 PM, Dionoid said:

Did you find structures or algorithms in the code that you didn't see before? E.g. those interleaved graphics?

I've seen interleaved graphics in the E.T. disassembly. I didn't use a MACRO to have those look better in the listing.


The most I gathered from Bob Whitehead's "pattern" is his reuse of code. Here in Football he used XOR more than most. I've seen this in his other games too.


The sound data is interleaved too. Using the same bytes he produced music for touchdowns, interceptions, and safety.

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