ioctl (General description)
ioctl performs low level calls to communicate with device drivers. As
there are lots of different device drivers, no really general description is
The DJGPP version tries to cope with two different flavors of
a DOSish and a UNIXish way. To distinguish between DOS-like and UNIX-like
calls, all valid DOS commands have all 3 MSB set to 0, the UNIX command have
at least one of the 3 MSB set to 1.