> I remember reading that the PIC can directly drive HC parts.  I can't find
> where I read it.  Is it true or do you need to use pullups as if interfacing
> to a TTL part?

They will drive pretty much any 5 V logic without any external components.

Remember that the old 74xx and 74Sxx chips should not have their inputs
driven hard above Vcc - 0.7V due to the quirky inputs, they should have a
470 Ohm resistor in series.  All other technologies should be a straight
connection.  No guarantees for ECL stuff though, there are TTL to ECL
converters if you must use them.

Cheers
--
Kalle Pihlajasaari     kalle@data.co.za
Interface Products     Box 15775, Doornfontein, 2028, South Africa
+27 (11) 402-7750      Fax: +27 (11) 402-7751