RE: Parallel port input help needed for limit switches

I'd use a 0.1uF on Vout and ground. And a 1.0uF on Vin and ground.
Make sure the polarity on the 1.0uF is correct. And if you're using a
monocap for the 0.1uF it doesn't matter about polarity.

And for the second time, it's _not_ "MC14069UB". It's a 4069. The letters
before and aft are manufacture designations.

www.digikey.com search for "4069 inverter", or "hex inverter"

Trade offs are 4069 needs resistors to communication with TTL because it's
CMOS. 74LS04 series chips do not require resistors to communicate with TTL
because it's TTL to TTL communication.

I'm not familiar with the other chips, since I don't have need for them.
But GOOGLE them, and read the specs.

I think it's up to you in what you use. Here are some links, that I highly
suggest you read.
http://www.play-hookey.com/digital/electronics/cmos_gates.html
http://www.play-hookey.com/digital/electronics/ttl_gates.html
http://www.fairchildsemi.com/an/AN/AN-314.pdf

It's a bit of an ambitious project. Probably for what you're going to use
them for, you probably don't need any of the special chips, or anything.
Especially if your going to use them for limit switches only.

What exactly are you going to do with them? Limit switches only?

If your machine has 3 axes, you only need 4 inputs. Wire the limit switches
in series, and 3 home switches.

If you have 4 axes, 5 (max) inputs. Limit switches in series, and 4(max)
home switches. I say max, because usually the 4th axis is rotary which
doesn't require a home really.