two output ports tied to 1 input??

This is what tristate was invented to do, and it is widely used.

You can have lots of tristateable memory chips attached to a common output bus, and as long as the outputs on only one mmeory chip are enabled at any one moment, the whole system works fine,

Sure, but what does the second output port do for anybody?

Quite a few open collectors outputs can be tied together - the limit is the leakage current drawn byt the "off" outputs - and they will function as a "wired AND" - any single output going low takes the output low, and all have to be high before the collective output can be high.

You could use two diodes and do the "el cheapo" OR gate ;-)

Two "regular" output ports in parallel will try to destroy each other if they're outputting opposite logic levels, but if you're driving them with the same signal, you should be able to get away with it, as long as you can put up with the glitches that happen because of the differences in propagation delay between the two.

Tri-state, yes - just only enable one at a time.

Open-collector/drain, yes, but your receiver won't be able to tell _which_ open collector/drain is pulling the bus low, so you have to know what you're trying to send. This is similar to the diode OR that someone else has suggested, but it still has the same caveat - you need a pull-up resistor to Vcc or Vdd. Maybe we should just call that 'Vh'. ;-)

Good Luck! Rich

Thank you all for the replies. Your information helped alot.

-Tony