NAME
       TD_GETGEOMETRY -- return the geometry of the drive.

   FUNCTION
	This command returns a full set of information about the
	layout of the drive. The information is returned in the
	DriveGeometry structure pointed to by io_Data.

   IO REQUEST INPUT
	io_Device	preset by the call to OpenDevice()
	io_Unit		preset by the call to OpenDevice()
	io_Command	TD_GETGEOMETRY
	io_Flags	0 or IOF_QUICK
	io_Data		Pointer to a DriveGeometry structure
	io_Length	sizeof(struct DriveGeometry)

   IO REQUEST RESULT
	io_Error - 0 for success, or an error code as defined in
	           <devices/trackdisk.h>

   NOTE
	This information may change when a disk in inserted when
	certain hardware is present.

   SEE ALSO
	TD_GETDRIVETYPE, TD_GETNUMTRACKS