Function            isDoubleDOS - is DoubleDOS installed

  Syntax              boolean isDoubleDOS(void);

  Prototype in        multihk.h

  Remarks             detects if Double DOS is running.

  Return value        returns TRUE if Double DOS is running, FALSE
                      otherwise.

  See also            DoubleDOSfreeCPU(), DoubleDOSGetVirtual(),
                      DoubleDOSTaskSwitch(), isInvisible()

  Example             #include <ibm.h>

                      main()
                      {
                           printf("Double DOS is ");
                           if (! isDoubleDOS())
                                printf("not ");
                           printf("installed");
                      }