What is Non Volatile Memory (NVM)?
Non-volatile memory or NVM refers to that particular type of memory or storage that can retain the data and information in it even after the computer system is turned off or there is a power failure.
Technically, these are byte addressable RAM for computers that helps to access data at individual byte level. In simple words, NVM does not need electric charge to retain its storage state but needs it only while reading and writing data on it.
Understanding Non Volatile Memory (NVM)
The Non Volatile Memory is also known by different names such as permanent storage, long term storage, or persistent storage solution.
It is an advanced storage technology that does not need a continuous supply of power to hold the data stored in it permanently.
The manufacturers make different types of such chips for different purposes such as to store program files, data and information, and controller program codes for devices.
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Typically, it is a secondary memory that has several uses and applications such as:
- Holding boot code while a computer is switched on
- Memory chips for digital cameras and USB memory sticks
- NOR flash memory in mobile phones
- Storage for text, photos, videos, SMS, call logs and more.
While communicating with the microprocessor, an application or any other device, these memory solutions can also vary significantly in a few other important aspects such as:
- Latency
- Capacity
- Endurance and
- Cost.
NMV is the broad assortment of devices and technologies that may vary extensively in their operating speed and manner in which these devices send or receive data.
Typically, the data in these memory solutions are written in two specific ways. It can be fabricated on the memory cells directly while the ROM circuits are manufactured.
Another way of doing it is to program them on the circuit using specific devices such as EPROMS.
However, the modern NVM storage solutions use flash technology in which data can be written on the circuit while the computer is in operation, just as it is done in the RAM.
Characteristics of Non Volatile Memory
The main characteristic feature of this permanent storage solution is that it does not need electric charge or power in order to retain the data stored in it, such as ROM.
This means that data and information can be stored in it permanently and cannot be transferred easily.
A few other notable characteristics of this memory are as follows:
- It is much slower and less economical in comparison to the volatile memory
- It offers larger storage capacity
- It does not allow the processor direct access to the data stored in it
- It is only a storage solution and does not have any direct effect on the system performance and
- It is more reliable but the process can typically read data but slowly.
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These permanent storage solutions usually have a shorter life expectancy due to their rewriting capabilities.
However, as compared with other types of storage solutions, the NVMs typically have a much lower read, write and erase latency.
Using static power, these memory solutions use less energy for every bit access while reading or writing and the endurance of the larger cells are also pretty high.
Types
Typically, non-volatile storage can be categorized into two main system types such as electrically addressed systems and mechanically addressed systems.
Here the electrically addressed NVM systems are costlier and use electrical mechanisms to read or write data but the mechanically addressed variants are larger and use a contact mechanism or a head to do the same on a magnetic storage media.
Based on the two broad categories and their respective attributes and specific technology, the long term storage solutions can be further grouped into five major types.
These are:
- Flash memory
- Magnetic or Magneto Resistive Random Access Memory or MRAM
- Ferroelectric Random Access Memory or FeRAM
- Phase Change Memory or PCM or PRAM and
- Resistive Random Access Memory or RRAM and ReRAM.
However, apart from the major types, these persistence storage solutions also come in other less-known types to meet with the growing demand for memory not only for storage but for other applications as well.
Some of the recent and notable developments have also added a few new types of permanent storage in the list that are gaining popularity slowly but surely in the NVM space are:
- Conductive Bridging RAM or CBRAM
- Domain Wall or Racetrack Memory referred to as DWM
- Millipede Non Volatile Memory and
- Nano Random Access Memory or NRAM.
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Supporting the newer technology, these memory solutions usually use a cross-sectional structure of MOSFET or Metal Oxide Semiconductor Field Effect Transistor called Silicon Oxide Nitride Oxide Silicon or SONOS.
Non Volatile Memory Example
The most common example of Non Volatile Memory in a computer is ROM or Read Only Memory.
A few other examples of NVM are:
- Flash memory
- Ferroelectric RAM
- Hard Disk Drives or HDD
- Solid State Drive or SSD
- Floppy disks
- Magnetic tapes and
- Optical discs such as CDs and DVDs.
The paper tapes and punched cards used in the computers earlier are also a type of persistent storage solution.
Is Non Volatile Memory RAM or ROM?
Ideally, RAM or Random Access Memory is a volatile memory since it loses data when the system is switched off but is economical and faster to fetch and store data.
On the other hand, ROM is a Non Volatile Memory which does not lose data when the system is shut down and it is slow and not economical.
Conclusion
Non Volatile Memory is very useful for storing data and information for a long time.
Since they do not need power to hold the data, it is most extensively used by people in one of the many forms they come in.
After reading this article now you know quite a bit about them and can choose one to meet your storage needs.