3.6 DISKETTS

Floppy disk is a convenient data recording medium. It is called floppy because it flops if you wave it (at least, the 5¼inch variety does). Floppy disks are portable and can be removed from the system. Disk drives for floppy disks are called floppy drives.

Data stored in Floppy disks are slower to access than that of hard disks. But it is less expensive than the hard disk.

Floppy Disks come into three sizes:

(1) 8 Inches Floppy Disk

(2) 5.25 Inches Floppy Disk

(3) 3.5 Inches Floppy Disk

The earliest floppy disks, invented at IBM company, were of 8 inches in diameter. They became commercially available in 1971. Floppy disks of today are available in two sizes 5.25 inches and 3.5 inches and their storage capacity ranges from 360 KB to 1.44 MB.

Floppy disks were very popular and have been seen by all computer professionals. This is the reason why floppy disk symbol is often seen in programs on buttons and other user interface elements related to  saving of files. Now pen drive have replaced flopy disks and flopy disks are outdated.


Note: Floppy Disks were used by computer professionals from the year 1971 to the year 2005 and are out dated now a days. Now pen drives have replaced floppy disks and are being used by the users.

3.6.1 Hard Disk Drive (HDD)

The hard disk drive in computer system is the data center of computer. All the programs and data of computer are stored in it. It is the most important permanent storage device of computer. Hard disk differs from the other data storage devices, in three ways:

Size (usually larger),

Speed (usually faster) and

Permanence (usually fixed in the PC and not removable).

The first PC hard disks had a capacity of 10 megabytes and its cost was very high. The Modern hard disks have capacities more than 500 gigabytes and are very cheap than to previous hard disks.


Features of HDD:

Some of the main features of hard disk are:

1. Performance: The hard disk plays a very important role in overall system performance. The speed at which the PC boots up and programs load is directly related to the hard disk speed.

2. Storage Capacity: Hard disks have a very high storage capacity such as 500 GB and even more. Bigger hard disk lets you store more programs and data in it.

3. Software Support: Newer software needs more space and faster hard disks to load it efficiently. This is supported by the present age high speed hard disk drives.

3.6.2 Random Access Memory (RAM)

Random access memory (RAM) of a computer system is a type of computer data storage device. It works similar to integrated circuits and allows the stored data to be accessed in any order, i.e. at random. The word random thus refers to the fact that any piece of data can be returned in a constant time, regardless of its physical location.

The RAM is a volatile memory i.e., the data or information saved in this memory gets lost if power is switched off. It is permanently fixed in side the computer system. 


Computer RAM comes into many sizes such as 256 MB, 512 MB, 1 GB, 2GB etc. Normal PC RAM’s and Laptop RAM’s are of different in sizes and shapes.

3.6.3 Pen Drive

A USB flash drive is a flash memory data storage device integrated with a USB (universal serial bus) interface. USB flash drives are typically removable and rewritable, much shorter than a floppy disk. Nothing actually moves in a flash drive: it is called a drive because it is designed to read and write data using the same system commands as a mechanical hard disk drive.

A flash drive is consist of a small printed circuit board protected inside a plastic, metal or rubberized case, robust enough to be carried with no additional protection, in a pocket or on a key chain. To access the drive it must be connected to a USB port, which powers the drive and allows it to send and receive data. 


USB flash drive offers potential advantage over other portable storage devices. They are more compact, faster, hold much more data, have a more durable design, and are more reliable for lack of moving parts. Pen Drive comes in various sizes such as: 256 MB, 512MB, 1 GB, 2GB, 4GB, & 8GB.

3.6.4 Compact Disk (CD)

The CD – ROM (Compact Disk read only memory) is a direct extension of audio CD. The CDs are available in the market since late 1982. Standard CDs have a diameter of 120 mm and can hold up to 80 minutes of audio. There is mini CDs with diameters ranging from 60 to 80 mm.

The amount of information that can be written on a CD is determined by the disc recording capacity as well as the physical and logical formats used. There are various versions of CD such as CDR (CD Readable), CDRW (CD ReadWrite), SACD (Super Audio CD), VCD (Video Compact Disk), and DVD (Digital Versatile Disk).


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