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Types of Computer memory

Computer memory is a highly essential component. The computer needs instructions to work, and these instructions reside on PC memory. To understand the computer working principle, you must know the various types of computer memory.

Manufacturers use RAM, ROM, cache memory inside the computer. Primary memory stores currently running program instructions on it. Secondary memory stores permanent data on it.

What is computer memory?

It is a storage device. The computer uses memory to store data and instructions. Computer memory stores information in it in binary form.

Computer memory

Types of computer memory

There are two basic types of memory.

  1. Primary memory.
  2. Secondary memory.
types of computer-memory
types of computer-memory

1. Primary memory

Primary memory is known as the main memory. The primary memory is a semiconductor memory.  Primary memory is the workspace for the processor.

What kinds of data or instructions are store in primary memory?

Primary memory holds a set of instructions or data on it which are needed to run the computer.  

There are two types of primary memory.

  1. RAM
  2. ROM

1. RAM

The full form of RAM is Random Access Memory.

RAM is a read-write memory.  

It is a temporary memory. RAM needs the power to store information or data into it. If the power is off, then all the saved information, data are erased automatically from the RAM. Therefore RAM is known as Volatile memory.

It is a faster memory than ROM.

RAM is a highly expensive memory than the ROM.

The storage capacity of RAM is low.

RAM stores set of instructions or data on it which are currently running inside the computer.  


  1. If your computer is on at that time, you can find the necessary OS files on the RAM.
  2. If you are working with ‘MS Word Application‘, then you can find essential MS Word files with the OS files on the RAM.

There are two types of RAM.

  •  SRAM
  •  DRAM

SRAM full form is Static Random Access Memory. Static random access memory does not need to refresh regularly to hold data on it. It can hold on data until power cuts.

SRAM is faster than DRAM.

It is expensive than DRAM.

SRAM consumes less power than DRAM.

In Computers SRAM is used as cache memory.


DRAM’s full form is Dynamic Random Access Memory. Dynamic random access memory needs to refresh periodically to hold data.

DRAM is slower memory.

It is a less expensive memory.

DRAM consumes high power.

There are different versions of DRAM.

  1. Asynchronous DRAM: It was the first type of DRAM. Now SDRAM replaced it.
  2. Synchronous DRAM(SDRAM): It is the newer version of DRAM. In today’s computer, you can find a new version of SDRAM. They are known as DDR SDRAM.

DDR SDRAM full form Double Data Rate Synchronous Dynamic Random Access Memory.

There are different versions of DDR SDRAM.

  1. DDR1
  2. DDR2
  3. DDR3
  4. DDR4

2. ROM

The full form of ROM is Read Only Memory.

ROM is not a read-write memory. It is a read only memory. Read Only Memory (ROM) is used in computers and other electronic devices (like washing machines, calculators, etc.).

It is a permanent memory. ROM always retains its data. Therefore ROM is Non Volatile memory.

Generally, ROM is used to store software that is rarely changed. The storage capacity of the ROM is very low.

Rom stores set of instruction that helps to boot a computer. And the manufacturer saved these instructions inside the computer ROM.

Boot means to start the computer.

Following are the list of various types of ROM:

  1. PROM
  2. EPROM


PROM full form Programmable Read Only Memory.

Users can write instructions in the PROM once. To program, PROM users need to use specific PROM programmable devices. If PROM is programmed after that it cannot be erased.


EPROM full form Erasable Programmable Read Only Memory.

Users can write instructions in the EPROM. Users can erase instructions from the EPROM and can rewrite again. With the help of Ultra Violet Rays, users can erase EPROM data.


EEPROM full form Electrically Erasable Programmable Read Only Memory.

Users can erase EEPROM data electrically.

2. Secondary memory

Secondary memory is also known as External memory.

It is Non Volatile memory.

These are magnetic and optical memory.

Some examples of Magnetic memories:

  • Hard Disk
  • Floppy Disk
  • Recording tape
  • Magnetic stripes on the credit card etc.

Some examples of Optical Memory:

  • CD
  • DVD
  • Blue Ray Discs.

Secondary memory is slower than the primary memory.

It is less expensive.

The storage capacity of the secondary memory is very high.

Memory Units

1nibble = 4bits

2nibbles = 1Byte = 8bits

1KiloByte = 1024Bytes

1MegaByte = 1024KiloBytes

1GigaBytes = 1024MegaBytes

1TeraByte = 1024GigaBytes



Memory is an essential part of a computer system. A computer needs a device that can store information on it. Memory fulfills the need for the computer. There are various types of computer memory used by the manufacturer to store information on it.

These memory have different speeds, sizes as well as they are used to complete various kind of task on the computer.

Related articles:

  • You can check to know “Basics of computer“. You will also know about the components of the computer, block diagrams of a computer.
  • The Article “Basic parts of PC” will help you know various input-output parts used on a PC.