PMOS and NMOS are commonly used for small memories and microprocessors.

A pulse is not perfectly square; it takes time for the digital level to rise from 0 up to 1 and to fall from 1 down to 0.

Interfacing (74HCMOS to 74ALSTTl or 74TTL to 74LSTTL) can be done with no danger.

Schottky logic overcomes the saturation and stored charge problem by placing a Schottky diode across the base-to-collector junction.

The basic part numbers of ICs are the same regardless of the manufacturer because digital logic ICs have been standardized.