Talk:Electronics/TTL

As far as I can see, this page describes RTL (Resistor-Transistor Logic) and not TTL. There is also DTL (Diode-transistor logic). DTL superceeded RTL and was in turn superceeded by TTL. TTL if I recall correctly was developed at least partly as a requirement of the Apollo moon program of the 1960s.

TTL as the name implies has 2 (at least) transistors in each gate. Key is the input transistor which often has multiple emitters. The emitters are free and used as the inputs for the gates. The base is connected via a resistor to +Vcc. Pulling down any of the emmiters will result in the collector of the input transistor being pulled down, which further transistors will pass to the output (perhaps with inversion to change functionality).

Errors
There are lots of things wrong here. It is RTL logic not TTL. The explanation of how current 'chooses' the path of least resistance is wrong. The battery in the diagrams is connected backwards. The base of the transistor is left floating instead of being either high or low voltage.