Computer Memory, RAM/ROM/Cache/Register/Buffer

Article on computer memory

Memory a device in computer which used to hold data or information.

There are many memories used in computer, we differentiate them on the basis of size, speed, cost and type of data to be stored.

  1. Main Memory RAM
  2. ROM
  3. Cache
  4. Register
  5. Buffer

1. Main Memory RAM

Stands for Random Access Memory store data before and after processing means when we input data in computer it is hold by RAM before it sends for execution to CPU, after execution output data is also hold by RAM. Anything displays on monitor or running task is hold by RAM. We cannot take input or output without RAM because it holds by RAM. RAM is expensive memory usually size in 2 to 4/5 GB, made of semiconductor material.

RAM Has further two types DRAM and SRAM.


  1. ROM

Stands for Read only memory used in computer, hold instruction written by manufacturer for booting process, instruction hold by ROM are called firmware. Data once write on ROM cannot be deleted or erased. ROM instruction executed automatically when computer turns on. There are further 3 types of ROM are EROM, EPROM, EEPROM. It is of fixed size made of semiconductor material.

  1. Cache

Cache is 3rd one memory also found on motherboard, its speed is faster then RAM but small in size then RAM, it is used to increase speed of CPU. When input data is taken by CPU from RAM, one copy of that data each time is stored in cache. If after processing again CPU needs some data it firstly looks in cache then RAM. Cache benefit is that, because each copy of input data is stored in cache so if CPU sometime needs same data again it fill found in Cache didn’t need to go to RAM, as Cache is faster then RAM so CPU read time from RAM is saved, so cache save CPU time.

  1. Register

Register are the smallest in size then any other memory and faster in speed. They are so small of size 1 or 2 byte. Registers are memory located in CPU and used by CPU to hold data during execution. There are more then 1 registers reside in CPU having different name size and function/data to hold.

  1. Buffer

Buffer actually is not a separate memory in system unit But it is a portion of RAM called buffer. Buffer is a location in memory which just used to hold data given by input or output devices.

Lets have a scenario for better understanding of memory concept.

Suppose your are given as assignment to write an article on storage in MS WORD into your computer.

What you will do??

Definitely you will power on your laptop, run application MS WORD and start typing. So when you power on your Computer ROM instruction executed first and that instruction load operating system(a system software to manage and control computer operations and make computer ready to work for you) into RAM. The you will look for MS word into your computer when you found you will click on that application icon. When you click MS Word its mean that software instruction loaded into RAM, when you’re creating your assignment your data is stored in RAM.

And RAM is temporary memory means if you shutdown application data would be deleted from RAM if you want that assignment back in future you need to save it on secondary storage for permanently. Then you will use option of save on disk.

Thank you.