What are the advantage of ttl?

Answer 1

TTL is faster than diode-transistor logic, and does both amplification and logical operations. While they are rather obsolete for most modern designs, they are good for simple and specialized products. So if you need a simple design that other people may need to modify later, then TTL circuits might be more feasible than using a microprocessor. TTL circuits are simple, well-documented, and well-understood. TTL circuits are also good for using for teaching purposes.