Excerpted from message dated 05-12-95, Paul Sidorsky to Paul Rider:

PS>OS/2 seems to have faster screen writes than DOS, but that may be
  >because there are 1000 clock ticks per second instead of 18.2.  It
  >can do a lot more. :-)

Paul--

    The DOS system clock (the PC timer counter) "ticks" (is updated)
about 18.2065 times per second (actually 1,573,040 ticks before
rollover, which is every 86,400 seconds, assuming the clock is
accurate).  The OS/2 system clock (the "real-time clock") "ticks"
exactly 31.25 times per second (same assumption).  These "tick rates"
indicate only the granularity of the system clock readings--an
indication of the significance of the value of a time interval measured
by two readings of the system clock (same assumption).

    Perhaps you misunderstood the meaning of the value given in your
OS/2 C compiler's time.h header for CLOCKS_PER_SECOND.  This value is an
artifact of the clock() function implementation in that particular
language processor, and has nothing to do with the actual system clock
tick rate.  A couple of examples from DOS C compilers I have owned:  The
MSC DOS C compiler v 5.1 used a value of 1000 for CLOCKS_PER_SECOND by
computing the system clock time from the PC timer counter value to the
nearest millisecond each time the program called for a value of clock().
On the other hand, the Borland DOS C compiler (v 3.1) effectively
counted system clock ticks by using the readings directly from the PC
timer counter; CLOCKS_PER_SECOND for that compiler is given as 18.2.

    In any case, the system clock tick interval has nothing to do with
how fast the display screen is rewritten.

          --Murray
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 * MR/2 2.23 #120 * "Have a frabjous day." he chortled in his joy
                                                 
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