help with sending data out the parallel port

[Peter Hansen]

David wrote:
> I'm wondering if python is capable of fairly precise timing and also sending
> data out the parallel port.
> 
> For example ; making a 7.5 KHz square wave come out of one of the data pins
> on the printer port.
> 
> I've tried to help myself with this one but searching in the "Python Library
> Reference" that installed with my version, [ Python 2.4.1. ]  yielded
> nothing on the subject of either timing or parallel port.

What are you trying to use this for?  What kind of jitter does your 
specification allow?  (That is, since you can't get the edge transitions 
exactly 66.6 microseconds apart all the time, how much variation are you 
able to handle?)  What will happen if, say, once every five or ten 
seconds the OS hiccups and prevents your task from running for a full 
second?

Doing this kind of high-speed realtime control on a non-realtime 
operating system is generally difficult or impossible, but it does 
depend on how precise you need to be, and how "soft" your realtime 
requirements are.  My gut feeling is that you cannot achieve what you 
want using Python on Windows (or Linux!), but it depends on your needs, 
not my gut. :-)

-Peter