NOR is a term from Boolean logic.
Its closely related but fundamentally different from theNANDgate and NAND logic because both are functionally complete operations.
They can express all other Boolean operators, such as AND, OR, or NOT.
The NOR gate itself relies on two or more inputs.
There are only two possible outputs they are usually expressed as 0 and 1 or High and Low.
These values represent the true/false states in Boolean logic.
If it gets 1 and 1, the output is also 0.
Only when all inputs are 0 is the output 1.
This also applies if there are more than two inputs.
NOR and NAND gates are popular architecture types in various PC and electronics parts.
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Use of NOR Gates
NOR-based memory isnt widespread in computers or smartphones.
The reason for this is the cost.
NAND flash offers far superior storage density and does so at a cheaper price point.
Several other vital differentiators also play a part.
NOR flash is slow at writing data.
This would make a NOR-flash-based SSD a problematic sell outside specific low-write use cases.
NOR flash does have some advantages, though.
Its fast when reading data.
Data can also be read in individual bits.
NOR flash has a low power draw and is quite resistant in challenging environments.
Depending on the writing requirement, writes can even be performed on the bit level in NOR flash.
Updating a bit from 1 to 0 can be done per bit.
However, erasing from 0 to 1 must be done at the block level.
Its the slow erasure process that makes NOR flash slowly at writing.
NOR-based memory does still have use cases.
Being slow to write limits use cases to ones with low numbers of expected write operations.
NOR is used in microcontrollers and to store things like firmware or BIOS.
These use cases typically dont require much storage, so the price or size isnt much of an issue.
Updates are expected to be a regular occurrence but may be needed occasionally.
Direct addressability is a substantial benefit, too, as the code can be directly executed without using RAM.
It was first described in 1880 by Charles Pierce and was shown to offer functional completeness.
This means it is possible to use combinations of only NOR gates to create all other boolean logic gates.
NAND is the only other boolean logic gate with which this can be done.
An OR gate is true if one of the inputs is true.
A NOR gate is true if neither onenorthe other input is true.
Tip:Neither the NOR nor the OR function should be confused with XOR.
The truth table explains the possible in- and output options mentioned above.
All combinations other than all 0s return a 1 and all 0 inputs return one as an output.
NOR gates and NAND gates have a property called functional completeness.
This means building any other logic gate using only NOR gates is possible.
This is done by repeating using multiple NOR gates in specific configurations.
Conclusion
NOR is a logic gate; it stands for Not-OR.
A NOR gate is the logical inverse of an OR gate.
An OR gate only returns false if all inputs are valid.
Conversely, a NOR gate is always true unless all inputs are wrong.
NOR gates are core components of NOR flash memory primarily used in microcontrollers or for storing firmware.
