TTL SIgnals - Pins?

Hello, the docs say that DirectRT can send TTL signals through a PC port, but I can't seem to find any reference as to which pins on the port carry the TTL signal. I need this information in order to build a custom electrical circuit that would receive these signals. Any help will be appreciated.

I'd refer you to this excellent overview:

[URL]http://retired.beyondlogic.org/spp/parallel.htm[/URL]

Summary: pins 2-9 are the data bus output. Pins 18-25 (inclusive) are ground.

And also double-remember that these signals are quite weakly buffered. Add some current limiting resistors, and watch out for accidental short circuits.

Thank you, much appreciated.