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Monday, August 6, 2018

What is Hardware? Definition & Example of Hardware


Hardware refers to the physical units of a computer.which includes electronic and electrical circuitry,components and devices.

Regulardless of its shape,size or capabilities, every computer that people use directly has same general design.

Computer Hardware = Processing Unit + Secondary Storage Devices + Peripheral Devices.The various units of computer hardware consist of the following components:

1.Central Processing Units(CPU)
  • Processor 
  • Primary Storage
2.Secondary Storage Devices ( External Storage)

  • Floppy Disks
  • Hard Disks
  • Tape
  • Optical Disks      
3.Peripheral Devices
  • Input Devices
  • Output Devices
  • Other peripherals

Types of external storage desices are as follows:

  • Floppy Disk

It is magentic storage media, using flat circular platter.Floppy disks are primarilly used on PCs.Information on a floppy disk is recoded in the magnetized states of particles of iron oxides evenly placed upon concentric circles known as Tracks.Tracks are further divided into sectors.The difference between the capacilites of double density and the qued density diskettes is in the number of tracks per tracks per inch (tpi)-48 tpi and 96 tpi, respectively, and in the number of sectors per track;usally this is eight or nine for ordinary diskettes and fifteen for high capacity diskettes.Physical size and storage capabilities of disks vary.

TYPE                                                         SIZE                                              CAPACITY

Double Density(DD)                                5.25"                                                   360 KB

High Density (HD)                                   5.25"                                                  1.2 MB

Double Density                                         3.5"                                                    720 KB

High Destiny                                            3.5"                                                     1.44 MB

Very High Density                                   3.5"                                                     2.88 MB

  • Hard Disks

It is a non-removable enclosed magnetic disk included in most PCs.It contains a stack of metal platters, each coated with iron oxide, that spin on a spinadle and entire unit is encased in a sealed chamber. A hard disk holds much more information than a floppy disk and is used to store relatively large amounts of data.The physical size and storage capabilities of a hard disk vary.For PCs , the storage capacities vary from 1GB to about 8-10 GB.On mainframe computers (explainedn later) the size of hard disk may vary from 8 or 16 GB to several gigabytes(GBs).

Technically microcomputer hard disks are called Winchester disks or fixed disks.These disks spin at an average speed of 3600 rpm (equivalent to 150m/hr) and unlike floppy disks they spin continously.

Winchester disk a paricular type of hard disks technology that uses a high density of data storage tracks and a very low flying read/write head,requiring a closely controlled operating enviroment.
  • Tape 
This is a plstic tape, usally made of mylar that is copted with iron oxide, thereby enabling the introduction (Writting);retention (Memory) and reading of magenetically recorded information.The best use of tape storage is for data that you do not use very often.A tape is a long strip of magenetic material;therefore the tape drive has to write data to it sequentially - one byte after another.

Tapes are sequential access media,which means to get to a particular point on the tape; the tape must go through all the preceding points. In contrast, disks are random access media because a disk drive can access any point at random without passing through intervening points. Therefore,tapes can not be practically used for data that you need often.They are mainly used for taking backup of hard disk. The tape capacity varies from few hundred kilobytes to several gigabytes.

  • Optical Disks  
The need for ever greater storage capacilites has driven hardware manufacturers to use optical storage technology as the main alternetive to magnetic storage. Optical storage techniques make use of the pinpoint precision possible with laser beams.

Types of popular optical disks are as follows:
  • WORM
  • CD-R
  • DVD

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