JoSS: Joy of Sharing Science No: 3

Your calculator is just a bunch of electrical switches
The holes coming from the emitter are now able to proceed to the collector and a
current is formed.
Transistors are used to make logic gates
Logic gates are the building blocks of digital systems. They accept one or more
inputs to produce an output according to a logical rule. Those inputs and outputs
are “truth-valued,” which are True and False in binary logic. In logic gates, 1 is
considered to be true, whereas 0 is false.
A logic gate is a small transistor circuit and is implemented in several forms to
create seven types of logic gates called AND, OR, NAND, NOR, XOR, XNOR, and
NOT. The circuit operates on two voltage levels called logic 0 and logic 1 and
receives its inputs according to the voltage level to which it is exposed.
Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is another type of a
transistor and one of the most widely used types. Its mechanism will not be
explained in detail here but will be mentioned only in relation to the construction of
the logic gates.
The switch behavior of MOS transistors are used to build the logic gates. A range of
analog voltages are assigned to each logic symbol according to the electrical
properties of the transistors. While the voltage range for 0 is between 0 and 0.5V,
some typical values for 1 are 5V, 3.3V, 2.9V, and 1.1V.
A complementary MOS (CMOS) circuit creates the logic gate. It uses both N-type
and P-type MOS transistors. P-type transistors are attached to the + voltage and
pull the output voltage up when the input is zero. N-type transistors are attached to
the GND, which is the reference point for signals or a common path in the circuit
from which all voltages are measured, and they pull the output voltage down when
the input is one. Hey also, when the input voltage to a P-type transistor is 1 (high),
then the transistor will not open (does not conduct).