The DDK includes source code for the IBMJOY joystick driver. Most of the driver code is located in a C language file called, IBMJOY.C. An assembly language file, POLL.ASM, contains a single assembly language routine, Poll, that interrogates the joystick for button press and coordinate information.
The remainder of this chapter describes the parts of the IBMJOY device driver that calculate button state and joystick position information. It begins with a brief description of the IBM Game Control Adapter.