IC Output Stage

This is a special chip which can use either for TTL or for nmos circuits. it can be used for level transform flexible.

What parameter do you want to test? if you hope to get itw output, dont forget to add a resistor on iits output terminal to power.

For the 3 state you can use 2 resistors for reliability. and apply probe of oscilloscope on it to view.

Open collector uses a switch element to pull the signal line down to ground level. You need to add a resistor (or something) to pull the signal line up to Vcc.

It's useful if you want to drive lots of ic inputs, just select an appropriate resistor to get the correct voltage swing or if you want to change voltage levels eg 5V TTL drive OC output with a resistor pulling the output up to 12V

All previous answers are correct.

Also open collector outputs can be used when you want to drive the same node with several devices. The node then forms a wired and: if all the outputs are "off" the pullup as shown in Del's diagram pulls the node to a logic one; if one or more of the outputs is "on" the node goes to a logic zero. You don't need to worry about disabling the other gates when only one is driving the node.

When two or more tri-state gates are connected to a single node you have to disable all but one or you will end up with contention (a fight between two or more outputs).

You can test a tri-state node (in its tri-state condition) by turning it off and making sure you can pull the output to both the positive and negative rails with a high value resistor (say 10KΩ).