jkenyon@css.itd.umich.edu (Jim Kenyon) (01/16/91)
I'm looking for a routine to give the joystick position from the game adapter. The IBM Tech Ref. description of the interface suggests busy waiting on the lower 4 bits of port 201h until they go low (each one can go low at a different time). The time taken to go low then can be used to calculate ([t-24.2]/0.11 = r) the resistance of the attatched pot. This is simple enough but these times are in micro seconds and the real time clock in the system can only be reprogrammed to micro second resolution (+/- 4uS is the granularity I get using the software I have). If you follow me this far, you can see that at low resistance values, the timer is only fine enough to give +/- 50% resistance accuracy. I must be missing something here since joysticks behave quite nicely as pointing devices and controls for video games on a PC -- please, enlighten me with a more elegant approach to game adapter programming. Thanks, Jim -- Jim Kenyon -- jkenyon@css.itd.umich.edu University of Michigan, 401 Washtenaw Ave Division of Kinsesiology, Motor Behavior Lab Ann Arbor, MI 48109 -- (313) 763-0498