Why you won't blow up your par port.
For the technically inclined that want to tell me I'm wrong: Original
TTL (but only a very small percentage of those running linux will have
such an old parallel port) was rated at 2ma at 2.4 volts. If you try
to hook up a LED to that, you will indeed exceed specs of the
chip. However the specs say max 2ma for a good reason. The reason
being in this case that they won't guarantee you that they will
deliver at least 2.4 volts (the lowest level that TTL is guaranteed to
see as a high level). If you try to draw 14ma from a TTL port (LED +
200 ohms resistor), you will most likely draw only 3 ma. Output
voltage will drop to 2V (resistor drop 0.6V, 200ohms -> 3 ma). You
will dissipate about 9 mW in the output stage of the chip. You should
start to worry if this goes above 60mW (0.5 W for 8 outputs). A
Cypress databook states that you're allowed to short one output at 85
mA for up to a second. (that's 425 mW). The Cypress manual further
states that for their dip packages (we're talking old TTL here) the
max junction to ambient (with no airflow) thermal resistence is about
100 C/W. At 0.5 W we'd get about 50 degrees temp rise. Max junction
temp is about 120 degrees. This leads to max ambient temp of 70
degrees. I don't think your computer is healthy (or going to stay
that way :-) if you have 70 degrees ambient and no airflow.....
summarizing, I'd say that according to the specs I have you're safe
if you stay below 20 ma in your LED. If you're scared though you can
also get a high yield LED, which works just fine at 2 ma.