DE> Unfortunatly, the program can be called in the startup routine and would 
 DE> most likely be in use until either shutdown or 
 DE> powerdown. This means that the semaphore might be left 
 DE> on disk

OS/2 Semaphores are not files.  Mike's suggestion (to use a sem to check
for a running instance) is the best one.

 DE> 3) Are you allowed to use the 1ch timer in OS/2? If not, how
 DE> can you synchronize timed events to the tic counter?

What's a tic counter?  (Just kidding).  Under OS/2,  you need not stoop to
such gimicks.  There are many ways to pass time (DosSleep), be woken up
periodically (DosStartTimer),  or to synchronize with other
threads/programs (DosWaitEventSem).   The APIs shown in brackets are just a
starting point...


 MB> Maybe you would get better answers if you backed up a
 MB> bit and explained in more broad terms what it is that 
 MB> you want to do.

 DE> Well, I need something more reliable in order to more reliably simulate
 DE> real-time operation (which I hear is a failing with 
 DE> OS/2). Interrupt driven is probably a key word here.

You didn't back up far enough.  What are you trying to do (what type of
device are you reading (if any),  how often,  and how much data)?

OS/2 is just fine for "real time",  as long as the
"time" is in the mSec range,  not uSec.


 void OS2Reboot (void)
 {
     HFILE  hf;
     ULONG dummy;
     ULONG rc;

     rc = DosOpen("DOS$", &hf, &dummy, 0L, FILE_NORMAL, FILE_OPEN,
         OPEN_ACCESS_WRITEONLY | OPEN_SHARE_DENYNONE |
         OPEN_FLAGS_FAIL_ON_ERROR, NULL);
     if(!rc)
     {
        printf ("\nShutdown...");
        rc = DosShutdown(0L);       // shut down file systems.
        if (rc) ErrorProc(rc);

        /* 32-Bit reboot */
        DosDevIOCtl( hf, 0xd5, 0xab, NULL, 0, NULL, NULL, 0, NULL );

        /* old 16-bit reboot
        DosDevIOCtl(NULL, NULL, 0xab, 0xd5, hf);
        */
        DosClose(hf);
     }
     else
       printf ("\nDOS.SYS not installed. Can't Reboot.");
 }


--- Maximus/2 2.02p1