Why would one chip (pokey) be used to produce sound and random numbers? That sounds like an odd combination.
The reason is distortion.
The Pokey chip can actually do even more stuff than just sound and random number generation (POKEY stands for "POT" and "KEY" as in Paddles and Keyboard). The way that sound and random number generation are related on the Pokey chip is for sound distortion. Distortion is useful in sound generation when don't want a pure tone (http://www.atariarchives.org/dere/chapt07.php#H7_2_4)
The Pokey chip includes a 17-bit poly-counter (polynomial counter) for purposes of generating long period sound distortion. This allows the chip to generate a pseduo-random sequence of "pulses" that it can use to filter the wave form of a "pure" tone and produce a distorted tone (useful to for things like explosions). The 17-bit poly-counter generates a fairly long pseudo-random sequence before repeating and according to http://www.ionpool.net/arcade/tempest_c ... /pokey.txt, the 17-bit poly-counter is also used for the Pokey's random number generation function.
The AY-3-8910 sound chip also has random number generation too - although few systems use it. The Centipede bootlegs are the only ones that I've come across so far. MAME just has a function pointer in the interface for this chip, and can easily be set to simply call mame_rand().
i've switched over to a trackball...
honestly it's taking a while to get used to it..
its a logitch marble trackball. (medium size), in the center
with buttons on either side..
i've tried shooting with the buttons on the controller,
but that doesn't feel right. so i switched to shooting
with the space bar for now....
i haven't noticed the analog overflow issue to much...
i used to play exclusively with a mouse, and actually
i think a mouse is actually a lot more accurate..
all my older scores were with a mouse..
anyways, millipede is KILLING ME... i've been checking out
don's replays, and using his savestates, the gameplay
at 700K is INSANE.. is this really the hardest game i've
ever played??? yes, i think so...although robotron,stargate,
and the upper levels of road runner are mind numbing too..
i only last for a few boards, and get crushed very quickly.
yeah, i know my reflexes aren't what they used to be..
anyways, who knows, maybe the trackball will work out..
by the way, i haven't adjusted any settings on them..
they work fine as they are for now..
