On Wed, 2005-10-19 at 11:45 -0700, John Waters wrote:
> Hi All,
> 
> I have a equipment whose operation invloves being triggered by a continuous 
> pulse train of 1 Hz at TTL level. Currently I'm using a funtion generator 
> with TTL o/p for doing that, but I want the operation be more automatic, so 
> I'm considering using the parallel port of a PC to replace the function 
> generator. However I wonder if the parallel port of a PC is TTL compatible. 
> Could anyone give some comments?

Most are TTL compatible. Some will only be 3.3V (i.e. laptops), which
might still work fine with TTL hardware, but I wouldn't count on that.

A bigger problem is how accurate do you need that 1Hz to be. If you're
running just DOS you can get it pretty close, but in Windows expect that
1Hz to glitch every once in a while.

TTYL

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