CBSE Class 11 & 12 Computer Science and Informatics Practices Python Materials, Video Lecture

Computer Memory

computer memory

What is Computer Memory:-
  • Memory is like the brain, which keeps computer data.
  • When the Input device sends data, it is saved in memory.
  • Where Computer Instructions, Results, or Information are saved; that is called Computer Memory.
Types Of Computer Memory:-
Types of Computer Memory 
Primary Memory
  • Primary memory stores data and instructions. It is also called the Main memory.
  • Primary Memory stays inside the CPU.
  • It has a lot of data processing capability.
  • It is called Volatile Memory because it lost the data when electricity is switched off. That means It cannot store the data permanently.
    Types of Primary Memory
    Types Of Primary Memory
  • It is directly accessed by the CPU. This includes several types of memory, such as the cache and ROM. However, in most cases, Primary Memory refers to RAM.
-R.A.M (Random Access Memory)-:
  • R.A.M. is a temporary Memory.
  • When a user gives the input, then firstly data saved in R.A.M. C.P.U. send only important data for further processing.
  • RAM lost the data when electricity is switched off, that's why it is called Volatile Memory.
R.A.M Capacity 
4MB , 8MB , 16MB , 32MB ,  64MB , 128MB , 256MB.

SRAM  (Static random access memory):-
  • S.R.A.M. is a form of semiconductor memory, which is made up of Transistors No Capacitor.
  • S.R.A.M. is used for microprocessors and electronic devices.
  • S.R.A.M. has low refresh, so data is saved for a long time
  • S.R.A.M. is costly as compare to D.R.A.M.
D.R.A.M. (Dynamic Random Access Memory):-
  • D.R.A.M. is a form of semiconductor memory, which is made up of Capacitor and Transistor.
  • D.R.A.M. is used for personal computer and workstation server.
  • D.R.A.M. needs to refresh very quickly.
  • D.R.A.M. refreshes thousands of times in 1 second. so data does not save for a long time.
  • D.R.A.M. speed is very slow compare to S.R.A.M.
-R.O.M (Read Only Memory) -:
  • R.O.M. is a permanent memory.
  • Programs are stored in R.O.M. when the computer is in production.
  • It does not lose the data when electricity is switched off. That is why ROM is called a Non Volatile Memory.
  • R.O.M. data can only be read.
P.R.O.M. (Programmable Read-only Memory):-
  • P.R.O.M. is a form of digital memory.
  • Data is saved to permanent.
  • Once saved data, can not be erased or changed.
E.P.R.O.M. (Erasable Programmable Read-only Memory)-:
  • a form of digital memory.
  • E.P.R.O.M. can be erased or re-used.
  • E.P.R.O.M. data can be erased by ultraviolet rays.
E.E.P.R.O.M. (Electrical Programmable Read-only Memory)-:
  • E.E.P.R.O.M. is a user-modifiable read-only memory.
  • data is can be erased through the electrical voltage method and can be rewritten.
Secondary Memory
  • Secondary memory keeps data and programs for a long term basis (Permanently).
  • It is of Large Capacity and Stores the Data Permanently.
  • Secondary memory is not directly connected to the CPU.
  • Hard Disk is generally referred to as Secondary Memory.  
  • It capacity is more in terabytes and it handles large data.
  • It is cheaper than primary memory.
Hard-disk, CD drive, CD ROM, DVD Drive, etc.

Cache Memory 
  • Cache Memory is unstable computer memory.
  • Cache Memory is a very special high-speed memory.
  • Cache Memory holds data that is used by the CPU frequently. So that it is requested by the CPU when needed and then CPU gets the data immediately.
  • Cache memory capacity is very low as compared to RAM and Hard disk.
  • Cache Memory is very costly.
  • Cache Memory is available on a microprocessor chip.
  • Cache Memory stores the data of the currently running program.
  • Cache Memory stores the temporary data.
Working of Cache Memory
Working of Cache Memory

Working of Cache Memory:-

  1. Cache memory resides on a microprocessor chip, it is the nearest to the CPU as compared to other kinds of memories.
  2. Computer data is stored permanently on Secondary Memory (Hard Disk). whenever User wants to process something in Computer the data comes to Primary Memory (RAM) from Secondary Memory.
  3. Now the data which is in RAM will be processed by the CPU. Now the Cache memories role comes into play.
  4. Because Cache Memory is an On-Chip memory, hence it can communicate with the CPU in a very fast manner. So, it stores the intermediate result of any operation.

Size Vs Speed of Computer Memory -:

Size Vs Speed of Computer Memory

As shown in the above diagram as the size of the memory increases the speed reduces. The cache memory has more speed than RAM and Hard Disk.

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