Subject:   -28- Timing on pre-1992 platforms
Date: 8 Apr 1994 00:00:01 EST

  Several libpf functions require high-resolution timing information.
  On most recent machines (Indy, Indigo, Indigo2, 4D/35 and Onyx) and
  PowerSeries or Crimson machines with IO3 boards, IRIS Performer uses
  special hardware counters with sub-microsecond resolution.  (The IO3
  board is standard on Crimson and recent 4D/300 and 4D/400 machines.
  You can check for it with the hinv(1M) command.)

  On other platforms, for example, those with IO2 boards, the
  time-of-day clock is used, which, by default, has a 10 ms
  resolution.  This resolution is inadequate for many libpf functions,
  including animation sequences (pfSequence), graphics load computation
  (pfChanStress), and the display of accurate channel statistics
  (pfDrawChanStats).

  To use any of these features on machines without high- resolution
  hardware timers, enable fast timers.  See the man page for ftimer for
  more information.  Frame rate control particularly bad on machines
  which lack both a fast clock and the video clock used by
  pfVClockSync.