Function            disktype - identify disk type

  Syntax              byte disktype(byte drive);

  Prototype in        ibm.h

  Remarks             disktype will determine the type of disk in the
                      disk drive being tested. drive specifies the drive
                      to check. Set drive to zero to specify the default
                      drive, one is A:, two is B:, etc.

  Return value        returns the drive id byte. See ibm.h for more
                      details.

  See also            diskchanged()

  Example             see demodisk.c