types of memory in computer

Types of computer memory


What is memory on a computer?

Memory is one of the most important things in any computer that is used by your machine’s software, hardware, and operating system.
So what is a computer memory definition? Computer memory is a device used to store data and programs that a computer can access at any time.
There are different types of computer memory, but they are all necessary, since each of them fulfills its own task for your machine to perform all functions and tasks properly.
A computer needs memory in order to store data and various instructions. Memory is divided into many categories, but the most important ones are primary and secondary memory.
And also there are volatile and nonvolatile memory types. Volatile memory types are used to store data when the computer is running, but when you turn off the machine, all data will be deleted.
Nonvolatile memory types are used to store data for long periods of time, and these types of memory can store data even when the computer is turned off.

Types of computer memory: Primary memory and Secondary memory

Primary memory

Primary memory is a volatile type of memory. It stores the instructions and information your computer needs to work. This data is not stored after the computer is turned off. Such a computer memory type is faster than the secondary memory, so it allows your computer to perform all tasks fast enough.
This speed is provided by the fact that the memory is located close to the CPU on the motherboard of the computer. This allows the CPU to read data from primary memory really very quickly.
Primary memory is divided into RAM and ROM.


By the name of the RAM (Random Access Memory), you can immediately understand what this computer memory type is for and what it does. RAM is designed to access data at high speed.
Unlike secondary memory, RAM can be used to access any bit of data at the same speed.
But this type of memory is not only very fast, but also expensive and volatile. Therefore, RAM is not used to store any data that you plan to use in the future.
To achieve optimal computer performance, 2 types of computer memory are used – primary and secondary.
RAM stores the data that the computer needs to work when it is turned on. And after your machine processes the data and it is not needed, it is moved to secondary memory, thus freeing up space for new data in RAM.
There are also different types of RAM: DRAM and SRAM.
DRAM is a dynamic RAM that is most commonly used in computers.
Now, in most cases, computers are supplied with dual data rate (DDR) DRAM. DDR has several versions: DDR2 , DDR3, and DDR4. All of them are newer and faster than DDR and require less energy.
But if you combine any of these DDRs, then you will not get any result, since different DDRs are incompatible.
So to get the best performance, you need to choose the same type of DDRs instead of, for example, DDR2 and DDR4.
SRAM is static RAM. This type is considered to be more expensive and faster than DRAM and is mainly used as a data cache in the CPU.
Its high speed and price is due to the fact that each SRAM cell contains several transistors.
If there is at least a very small SRAM cache for the most essential data, it can significantly increase the speed of your system.


By the name “Read Only Memory” it is easy to understand that this type of memory stores information, but does not allow writing new ones. Unlike RAM, ROM is a non-volatile type of memory, which means that all the data that is stored there will continue to be there, even if you turn off the computer.
The main purpose of a ROM is to store data and instructions that are needed in order to run an operating system. As you can imagine, this type of computer memory is fast enough to immediately start the entire system as soon as you press the power button on the computer.
Like RAM, ROM is also divided into several categories: PROM, EPROM and EEPROM.
This type of memory is designed for the users to be able to write instructions to it themselves.
The main difference between the PROM and the ROM is that the user cannot write or change anything to the ROM. But don’t think that you can do such a thing on the PROM more than once.
You can code and erase instructions and data just once and after that no changes can be made.
As you can see from the name, this type of memory allows users to repeatedly write new data and erase old one, as well as reprogram it.
But this process is not as easy as burning a disc, for example.
To write new data and instructions, you first need to free up space from old ones. To do this, you need to remove the memory from the computer and erase every cell in the EPROM by exposure to ultraviolet light.
The EPROM will then be ready for rewriting.
EEPROM is a type of memory that can be programmed, changed, and erased repeatedly.
But the process of erasing data is not as difficult as for an EPROM. The difference lies in the fact that in order to erase data from the EEPROM, it does not need to be taken out of the computer and exposed to ultraviolet light. To get rid of unnecessary data, you can use the computer system in which the memory is located.
This feature makes it seem like this memory is used for more than just reading. But the fact is that the writing process itself takes a lot of time and most often the EEPROM is used in order to update the program code (for example, BIOS).
It is also possible to erase only certain parts of the chip rather than the entire chip.

Secondary Memory

Secondary memory (also called storage) is the nonvolatile memory of a computer that stores all of your data and programs. After you turn off your computer, all data in the storage will remain there. The processor does not directly access the secondary memory, unlike the primary memory. Also, the difference from primary and secondary memory lies in the fact that the secondary memory can be easily changed, and data can be deleted and saved a large number of times without much difficulty.
Also, secondary memory is much cheaper than primary memory in terms of cost per gigabyte, but it is also slower.
The main types of secondary storage used in a computer are magnetic storage devices, solid state storage devices, and optical storage devices.

Magnetic storage devices

Magnetic storage devices use a magnetized medium to store data.
It is easy to write and erase data on them, and they can also have a sufficiently large amount of memory.
The most famous example of such a device is the hard drive.

Solid state storage devices

Solid state storage is a storage device that uses silicon microchips to store data.
Unlike magnetic storage devices, solid state storage has no moving parts and is therefore more reliable.
Solid state storage is also more expensive, but also significantly faster.
Examples of such a device are SSD, USB flash drive, and SD card.

Optical storage devices

Optical storage devices write and read data using a laser.
Their advantage is that they can be easily removed from the computer and transported wherever you need.
Also, such devices are not particularly expensive, but now they are not as popular as other types of secondary storage.
Examples of optical storage devices: CD-R and CD-RW discs, Blu-ray discs and DVD-R, DVD-RW discs.

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Frequently Asked Questions

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