6 replies to this topic

[flammingcowz]

I know that there are some games that let go past certain boundaries and play through parts that you're not supposed to. I think the explanation was that you're playing inside of the RAM.

For example, in Mountain King when you go to the top and mess around up there, or River Raid at a certain point, or even the arcade Pac-Man last level.

Are there any games for the 2600, probably homebrew, that are programmed specifically to let you play around in the randomness of the machine?

[FujiSkunk]

It's not that you're necessarily playing around in RAM (thought that is the case in 2600 Mountain King) it's that you're causing the game to use data intended for other purposes to render the playfield.  This other data could come from RAM or from another part of the ROM.

Yars' Revenge does this intentionally.  The "Neutral Zone" is rendered by treating other game code as display data.

Edited by FujiSkunk, Fri Jun 22, 2012 10:28 AM.

[Thomas Jentzsch]

I am pretty sure some games use code for explosion data.

[5-11under]

Thomas Jentzsch, on Fri Jun 22, 2012 10:29 AM, said:

I am pretty sure some games use code for explosion data.

... might be useful for pseudo random number generation, too, probably with some massaging of the data... .

Edited by 5-11under, Fri Jun 22, 2012 10:33 AM.

[Master Phruby]

FujiSkunk, on Fri Jun 22, 2012 10:17 AM, said:

Yars' Revenge does this intentionally. The "Neutral Zone" is rendered by treating other game code as display data.

That's pretty cleaver. I wonder if any game characters show up randomly in the static.

[Syntaxerror999]

FujiSkunk, on Fri Jun 22, 2012 10:17 AM, said:

It's not that you're necessarily playing around in RAM (thought that is the case in 2600 Mountain King) it's that you're causing the game to use data intended for other purposes to render the playfield.  This other data could come from RAM or from another part of the ROM.

Yars' Revenge does this intentionally.  The "Neutral Zone" is rendered by treating other game code as display data.

Oh like in super mario bro. when you get past 99 lives

[theloon]

I haven't heard much about 2600 games that let you unintentionally use code or RAM as game data.  My theory is that less code means less chances for big bugs like that.  These programmers would manually do code reduction so they knew their code inside and out - sometimes sideways.  Nintendo was the first company I heard of that that separated original programmers from code optimizers.

The NES is the first system I had that allowed this kind of bug frequently.  Wizards & Warriors and Super Pitfall being two I personally "discovered" as a kid.

Edited by theloon, Sat Jun 23, 2012 9:06 AM.