MAMEWorld Forums - EmuChat - Re: Random generators in PCB vs mame

> Recent discussion about DK barrels and different play between various versions of
> mame and the pcb's brings this to mind...
>
> Depending on how the "random" is generated, I would imagine the pcb vs the emulated
> version could have drastic differences in "random" events, making gameplay on a
> competative level vastly different.
>
> Another case in point is Hatris. Gatinha plays this alot (and is pending varification
> of her world record score)... she gets quite a few blue flames with the current
> version of mame, but has seen only one blue flame among probably fifty or more plays
> in the version required for score verification (which is based on mame.106). Makes a
> HUGE difference in game play. I have a hatris pcb... and once I get around to setting
> up a jamma getup, we'll be able to compare gameplay on the actual pcb as well. Maybe
> I could do a statistical analysis of blue flame frequency between the two versions of
> mame and the pcb for comparison purposes.
>
> But getting around to the question at some point... is there any thing that could be
> done in emulation to approximate the original pcb's "random" frequencies... or is
> this just taking emulation too far given the huge variety of processors and speeds
> out there?

[Don Hodges wrote:]> > Let me know if you want me to look at other game's random number generators.
>
> Yes, please look at hatris... what determines the arrival of a red or blue flame?

From what I can tell, each hat has a chance of being a red fire. This chance depends on how many hat sets have been completed:

0-10 sets: 3/256 chance
11-15 sets: 5/256 chance
16-50 sets: 10/256 chance
over 51 sets: 15/256

If both hats are set to a fire, the game checks for this and resets one of the fires back to a hat.

The program keeps track of how many flames have appeared. After every 7th red flame, the next flame that appears will be blue.* [there is a 1/256 chance that this will not happen, and the 8th flame will stay red.]

Don Hodges
www.donhodges.com

Edited by Phantom DJ (09/26/10 07:20 AM)