RE: [stella] disassembling River Raid

Subject: RE: [stella] disassembling River Raid
From: Mark De Smet <de-smet@xxxxxxxxxxxxxxx>
Date: Mon, 6 Aug 2001 19:30:21 -0500 (CDT)
> > after disassembling Starmaster, I want to try River Raid now, because I
> want to know exactly how the terrain generator works.

I'd be interested in reading that ;-)

> Oh, yeah!! I'm sure that the kernel code is the trick of the century. it
> seems to use very big tables (maybe for smart position and drawing routines,
> and the playfield graphics...)

As Carol Shaw explained in "Stella at 20 V2"(Thanks Glenn!), it is
generated with a Pseudo random number generator(a LFSR).  IIRC in the
video she debates the size of it, but thinks it is 15 bits, which would
put it at 32767(*2 for the straight levels) different screens, without any
tables necessary.

Please let us know how it turns out!


Thomas, if you are unfamiliar with LFSR's, mention it, and I'm sure
someone on the list can explain.  I would probably help in figuring out
the code.

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