Re: Newbie theoretical...updated

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: : Yes that summarizes my question exactly... in the original game, the cpu can be told via hardware that buttons a,b,and c are pressed at the same time. With a keyboard hack or encoder, mame sees the presses come in serially. : No, the computer sees the presses serially. Mame does not. Mame polls the computer's "current keyboard state"; or, in another view, an "unbuffered" keyboard. The keyboard state is kept track of the keypress signals by the OS. (sorry, I'm being nit-picky) : : The question then becomes, is the serial entry of the 3 keypresses from an encoder into mame fast enough for the game rom to consider it "simulatanious"? : The question should be: is the computer OS receiving the key press signals from the encoder faster than mame is polling the keyboard state. : : If everyone could just fire up streetfighterII, play : : Zangeif, and try his clothesline spin by pressing the 3 punch buttons at the same time....I get about 50% success rate. : Well I did a quick 3 key press test: my hotrod vs my keyboard. : keyboard: ~40% : hotrod : ~75% : I don't know how much was do to me not pressing all at the same time (but I know at the arcade, years ago, I was about 75% with the 3 key press too.) : The keyboard rate could be lowwer due to ghosting or it being harder for me to press the keys at exactly the same time, but it could also be due to a slower encoder. : How this helps. : : : Note that most normal keyboard encoders are slower than those used in the I-pac, Hagstroms, etc. With the bandwidth limits of the keyboard port, you still will get some polls while the changes are still "in the pipe", but a lot less than with slower encoders. : : >I don't think the original poster was talking >>about ghosting, I think he was saying that on >an original game, the processor could just go >out and read all the inputs at once, whereas in >MAME, or with the keyboard or IPAC etc, the PC >will actually get the individual key presses >over the serial keyboard link, so that if you >press say : : >: : "a, b, and c" at the same time, on the >original arcade game, the processor would see >exactly that. On a keyboard or encoder, the >processor will see a keypress event for a, then >a keypress for b, then a keypress for c. >(although the order may be : : : : random).

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