YAN-1 said:
ok ok. sorry. let me clarify. this is the story:
i am controlling a car. now a main program run by the pentium 4 will do certain calculations and send for example the required speed of the car to a PIC so that it can control a dc motor on the gas pedal. now there is a PIC to control the speed, another for the steering, and so on. the pentium will send these orders to the PICs through the PCI card. but i am not sure whether to use serial or parallel interface and how to make sure the data transfer rates match so that i don't lose any data?
That's an entirely different story!.
As Jay says, why are you talking about PCI cards?, you only need a VERY SLOW interface, you're controlling slow mechanical devices - a 9600 baud serial interface would be plenty fast enough.
Basically you're wanting to 'radio control' a car?, your main problems will be mechanical - you will need to buy (or make yourself) large powerful servo systems to handle the controls.
Incidently, standard radio control system use pulse width coding to drive the servos, these are refreshed every 20mS - that's only 50 times a second!. This provides perfectly acceptable control, and 9600 baud would beat that by a good margin! - no need for anything faster at all.
There's also probably no need to use multiple PIC's?, you could use a single one to receive the 9600 baud serial data, and output pulse width codes to drive servos. Such devices are freely available, and commonly used in robotics!.
BTW, I don't know if you ever watch Mythbusters, but they radio controlled a full size car - to check the 'drive shaft breaking' myth.