LH>
  > Writing to the screen one character at a time is horribly slow.
LH>

  One easy way to speed up screen access over the one-character-at-a-time
  method is to use double buffering.  Write all changes to a
  screen-sized buffer, and then use VioWrtCellStr to write the buffer to
  display memory all in one go.

  Of course, you can further optimise this when you know that only lines
  X to Y of the buffer have been modified, by modifying the call to
  VioWrtCellStr to only write out lines X to Y.

  One general rule of OS/2 I/O, that applies to everything from serial
  I/O to the VIO subsystem, is that when you have lots of characters to
  read from or write to a device, the more of those characters that you
  can deal with in one single system call, the better.

  Incidentally, to ensure that your program will work well for all user
  tastes, ensure that your screen buffer can handle screens of any size
  from 1x1 up to 132x102.

  > JdeBP <
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