#: 20196 S1/General Interest
    09-Aug-94  19:06:07
Sb: #20193-#RS232 response time?
Fm: Kevin Darling 76703,4227
To: Simon R Ashby 100111,2173 (X)

Okay.  My best guess:

It sounds like they're probably using their main process to answer you once
they hit a main loop area where it can notice your input... and that the main
process takes a max of 25ms to get around to this area.

What they might try doing is:

  * Have a background process of high priority waiting for your tick. (It could
even just always have a one-byte read pending vs polling the serial port.)

  * Share a data module (containing the latest desired text annotation) with
the main process and the background process.

  * The background process can then respond to your tick fairly immediately.

This assumes, of course, that they don't have any far more critical (higher
priority) processes or long interrupt routines.  No OS can handle the case
where there are more high-priority processes than there is cpu power to handle
them :-)

best - kevin

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