Storage Devices

Computer Memory:

The area of a computer where programs and data are stored is called memory. It stores the programs and data permanently or temporarily.
 



Types of Computer Memory:

There are two major types of computer‟s memory:-

1.                  Main Memory or Internal Memory or Primary Memory

The main memory (or primary storage) of a computer is memory that is wired directly to the processor, consisting of RAM and ROM. The processor or CPU has almost direct access to the main memory. In order to match the CPU speed the main memory is made very high speed memory. It is divided into two parts

             RAM: 
          RAM is the type of primary memory where data and programs are temporarily stored. RAM only holds information when the computer is on. Everything stored in RAM is lost when the computer is turned OFF. That‟s why it is called volatile memory. It is also called Random Access Memory''

 

RAM:

          Random Access Memory (RAM) is a type of data storage used in computers that is generally located on the motherboard. This type of memory is volatile and all information that was stored in RAM is lost when the computer is turned off.

2.                  Secondary Memory or Backing Storage or Auxiliary Storage:

Secondary memory (or secondary storage) is the slowest and cheapest form of  memory. It provides very high storage capacity. It cannot be accessed directly by the CPU. Secondary memory devices include magnetic disks like hard drives and  floppy disks ; optical disks such as CDs and CDROMs ; and magnetic tapes, which were the first forms of secondary memory. 

 

Hard Disks:

The hard disk is a magnetic disk, Access to data is faster than access to floppy disks. Hard disks store more data than floppy disks. They are more reliable then floppy disks - there is better protection against dirt. Hard disks are used to store the operating system, application software and users' files.

 

A hard disk is made of a rigid disk. Hard disks spin much more quickly than floppy disks and the disk read/write head is positioned very close to the disk. Because the disk head is positioned so close to the disk hard drives can easily be damaged by dust or vibration. Therefore to protect the disk sealed case is used. This picture shows a hard disk drive with the case removed. Disks in Hard drive is also called Platters.