Storage Units or Memory || BCA / B. Tech / BSc. || #DDU #computer

Storage Units or Memory || BCA / B. Tech / BSc. || #DDU #computer

Memory

The Memory is an essential component of a computer system. It is required by the computer system to store instructions and data.

Memory can be divided into the following two types:

(a) Primary or main Memory:

• It is one which is directly connected to the CPU or part of the CPU in some PCs.

(b) Secondary Memory:

• It is external to CPU.

Primary Memory or Main Memory

Primary memory is a small but relatively fast storage unit that stores data and instructions which are used by the CPU. This type of memory is also known as Main Memory. Primary memory is a temporary memory. It retains its contents only for the time that the computer is switched on. As soon as it is switched off, the main memory loses its contents.

Secondary Memory or Auxiliary Memory

Secondary memory or secondary storage devices are permanent storage units used for storing programs and data. They use the principle of magnetization for storing 1 and 0. Therefore, they are also known as magnetic memory. They are non-volatile, i.e, the memory retains its contents even when power is switched off.

Examples of secondary storage devices include magnetic tapes, magnetic disks, compact disks, magnetic bubble memory, magnetic drums, zip disks, etc. The relatively slow magnetic tapes are used for storing very old files. Magnetic disks are used for storing data for backup purposes.

A disk that is permanently attached to the computer unit and cannot be easily removed by user is called the Hard Disk. A Floppy Disk is a removable disk. A new breed of disks called zip disks (of the size of floppy disks) and pen drives are now available which enable you to store about 2 GB or more of data on them.