TTL inverter circuit and its internal structure

Shown is a TTL integrated circuit with 6 inverters (SN7404, M53204P). The internal circuit structure of each inverter
is also shown in the figure.
    The DC voltage +5 V provides power for each inverter. When the input terminal A is high level (number "l"), the transistor VT1 is turned off,
the transistor VT2 is turned on, the diode VD2 is turned off, the transistor VT3 is turned on, and the output terminal A is low level (digit "o"). If the input terminal
A is low level (digital "O"), the circuit undergoes a reverse phase change, then the output terminal A is high level ,