Engineering Homework Help

I’m studying for my Electrical Engineering class and don’t understand how to answer this. Can you help me study?

1. TTL elements with open collector: circuitry, operation principle, parameters.

2. Which of the switching circuits of the bipolar transistor has:

            a- the largest input resistance,               

            b – the largest current gain,

            c – the largest voltage gain

3. . Provide transmission of digital information from CMOS gate (Ucc = + 5V) to SN74S gate