Problems understanding pin connections

Any good book that explains digital logic should do this. I would imagine it's in the ARRL handbook or "The Art of Electronics" by Horowitz & Hill (I'm not sure, though).

Here's a quick guide, though:

"Push-pull" (normal output) -- Actively supplies current from VCC to pull the voltage up, and pulls current to VEE to pull the voltage down. In CMOS this means it has a P-type transistor to VCC and an N-type transistor to VEE.

"Open-drain" (or open collector) -- Has a transistor to ground, either N-type MOS or NPN in TTL.

"Tri-state" -- Has pull-up and pull-down transistors, with a control line to turn both off. Hence, three states -- high voltage, low voltage or high impedance (to let other devices drive the line).

In addition to this you need to pay attention to old-style TTL logic interfaced to CMOS: a 5V TTL part is only guaranteed to drive about 2.7V or so as a "high", which is less than what 5V CMOS is guaranteed to respond to. If you want to interface TTL to CMOS you have to use special CMOS parts with a lower threshold. Ditto for interfacing parts with a 3.3V VSS to parts with a 5V VSS.