TABLE OF CONTENTS Logic gates are grouped into "families" and "systems" based on similarities in manufacturing process. Examples of logic families are Diode Logic (DL), Resistor Transistor Logic (RTL), Resistor Capacitor Transistor Logic (RCTL), Diode Transistor Logic (DTL), Transistor Transistor Logic (TTL), Emitter Coupled Transistor Logic (ECL), and Complementary Metal Oxide Semiconductor Logic (CMOS).
The maximum number of inputs that can be applied to a logic gate is known as fan-in.
A 4-input NOR gate can have up to four input lines. So, a 4-input NOR gate has a fan-in of 4.
Sometimes the output from one gate will be used as input for the next stage. The fan-out of a logic gate is the maximum number of gates that a particular logic gate can drive.
If a typical NOR gate has a fan-out of 8, then it can drive eight gates from its output.
A gate's fan-in is called its input loading capability and the fan-out is its output loading capability. Together they are called loading factors.
The transfer characteristics of a logic gate are represented by a curve relating the output voltage to the input voltage. The curve is plotted on a graph where the input voltage is on the x-axis and the output voltage is on the y-axis.
So far, we have considered logic-1 and logic-0 as having a constant voltage level. In actuality, they do not have a single precise voltage...
