Showing posts with label Input Output Device. Show all posts
Showing posts with label Input Output Device. Show all posts

Printer and its classifications


A printer is peripheral device,which receives data from computer and prints it on a paper.That is it simple acts like an output device for the system.Printer are classified mainly in two types -
  • Impact Printers
  • Non impact printers


Impact printer:

An impact printers are those in which the characters are printed by impacting the print head or hammer to the roller or platen. In this type of printer the print head makes a contact with the paper physically.There are several types of impact printers-
impact printer
  • Dot Matrix printers(DMP)
  • Band printers
  • Drum Printers
  • Daisy wheel printers
The general features of impact printers are-
  • Uses force by applying hammer pins to strike the paper
  • Slow speed in characters per second
  • Prints on most paper types
  • Transparencies not supported
  • Multiple copies may be printed at once


  • Very low operating costs.
  • It can print on continuous stationary.
  • Dot matrix priters can create carbon copies when carbonated paper is used.


  • The print quality is very poor.
  •  Very slow going machine-it ranges from 40 character per second (cps) to about 1000 cps.
  • The machine is very noisy-can not be used near a telephone line.
  • It cannot produce color copies.

Non-Impact printers:

Non impact printers are those printers,which prints the characters by image formation similar to Xerox. In this type the print head never touches the paper physically. The outputs of these printers are of better quality compare to the impact printers. Most over it we compare the speed bettween impact and non-impact printers the non-impact printers are faster than the impact printers.These are several types of non-impact printers.
non-impact printer
  • Laser Printers
  • Ink Jet Printer
 The general features of non-impact printers are-
  • Print head does not make contact with the paper
  • Higher speed in characters per second is posible
  • Prints on most paper types but better quality obtained with better paper 
  • Transparencies usually supported

  • It is a high resolution machine which range from 300 to 600 dpi (dots per inch).
  • They are comparatively small and lighter in weight.
  • It is almost noiseless.
  • Very high quality printout.
  • Less costly.

  • It is slow as compared to laser printer.
  • The cartridges cost more per pages than laser printer cartridge.
  • Cartridges need to be replaced more frequently than the laser printer.
  • Can not be used continuously for log
  • Color printing can take 25-30 seconds each page.

Most Useful Keyboard Shortcut Key

Computer keyboard Shortcut key  :

shortcut keyShortcut key is the most important to use computer knowledge. It is less working time using keyboard short cut key. Using keyboard shortcuts can greatly increase your productivity, reduce repetitive strain, and help keep you focused. For example, highlighting text with the keyboard and pressing Ctrl + C is much faster than taking your hand from the keyboard, highlighting the text using the mouse, clicking copy from the file menu, and then putting your hand back in place on the keyboard.

Ctrl + C or Ctrl + Insert

Copy the highlighted text or selected item.

Ctrl + V or Shift + Insert

Paste the text or object that's in the clipboard.

Ctrl + Z and Ctrl + Y

Undo any change. For example, if you cut text, pressing this will undo it. This can also often be pressed multiple times to undo multiple changes. Pressing Ctrl + Y would redo the undo.

Ctrl + F

Open the Find in any program. This includes your Internet browser to find text on the current page.

Alt + Tab or Ctrl + Tab

Quickly switch between open programs moving forward.
Tip: Press Ctrl + Tab to switch between tabs in a program.
Tip: Adding the Shift key to Alt + Tab or Ctrl + Tab will move backwards. For example, if you are pressing Alt + Tab and pass the program you want to switch to, press Alt + Shift + Tab to move backwards to that program.
Tip: Windows Vista and 7 users can also press the Windows Key + Tab to switch through open programs in a full screenshot of the Window.

Ctrl + Back space and Ctrl + Left or Right arrow

Pressing Ctrl + Backspace will delete a full word at a time instead of a single character.
Holding down the Ctrl key while pressing the left or right arrow will move the cursor one word at a time instead of one character at a time. If you wanted to highlight one word at a time you can hold down Ctrl + Shift and then press the left or right arrow key to move one word at a time in that direction while highlighting each word.

Ctrl + S

While working on a document or other file in almost every program pressing Ctrl + S will save that file. This shortcut key should be used frequently anytime you're working on anything important.

Ctrl + Home or Ctrl + End

Move the cursor to the beginning or end of a document.

Ctrl + P

Print the page being viewed. For example, the document in Microsoft Word or the web page in your Internet browser.

Win +R

Show run comment, and go any where. Exmple – Win+R+cmd (Command prompt), Win +R+ Notepad (Notepad) ,Win+ R+ Mspaint (Microsoft Paint) etc..

 Page Up, Space bar, and Page Down

Pressing either the page up or page down key will move that page one page at a time in that direction. When browsing the Internet pressing the space bar will also move the page down one page at a time. If you press Shift and the Space bar the page will go up a page at a time.

Tip: If you are using the space bar to go down one page at a time press the Shift key and space bar to go up one page at a time. 

Computer Input Device


Scanner is input device. It is facilities capturing the information and storing them in graphic format for displaying back on the graphical screen.

It consist  of two components ,the first one to illuminate the page so that the optical image can be captured and the second part convert the optical image into digital format for storage by computers.
The graphical image scanned can now be seen and processed directly by the computer.

Advantages of scanner:

  • Any image can be converted from paper into digital format which can be used latter in other computer documents.
  • Of various types of scanner flatbed scanner are very accurate and can produce images ,of high quality.

Disadvantages of scanner:

  • Image can take up a lot of memory space.
  • The quality of the final image depends upon the quality of original documents.


Digitizer is an input device. Digitizer or Drawing board is device by which drawing, drafting, mapping, desktop publishing, animation and presentation graphics can be done. The drawing or the sketch is first placed on digitizer lablet and then through tracing the graphic information can be converted into accurate digital information by the digitizer and which the enter into computer.

Input Device

Light Pen

This is a pen -shaped device allowing natural movement on the screen. With the help of this pointing device any menu/icon can be selected or any line can be drawn on the screen.Light pen is like a pen but on its back side there is a long tail like wire connected with the computer.It contains a light
Light pen
Light Pen
receptor which is activated by pressing the pen against the screen . Receptor is the scanning beam which helps in locating the pen's position.

Advantage of light pen :

  • Very easy to use.
  • It is useful for programs like CAD (Computer Aided Design) for changing shape ,size, location etc. on the screen image.
  • It can directly draw on screen

Disadvantages of light pen:

  • It is not so accurate while drawing .
  • It is comparatively expensive compared alternate pointing device like mouse.
  • Tiresome after long hours usages.

 Joy Sticks :

Joy sticks is also a pointing device which is used more on entertainment usage like games.

 Joy Sticks
Joy sticks

Input Output Devices

Input Output Devices

The Computer will be of no use if it is not communicating with the external world. Thus a computer must have a system to receive information from outside world and must be able to communicate result to external world. So ,a computer must contain an input/output(I/O) devices.

It include two basic components, one is the I/O devices and another called I/O module.

Input Devices :

These ,as the name suggests,are used for transferring user's command or choise or data from the external world the computer.

Input information may be program or data. The input devices are Keyboard, Floppy disk, Punch card, Mouse, Scanner, Digitizer, Visual Display unit (VDU), Voice input system, Magnetic tape device,  Light pen (Joystick) Analog to Digital converter (ADC) etc..

Main Function of the input unit is
  • To take instructions or data from the outside world
  • To transform them into binary form,and
  • Sends the converted instructions and data to the computer system for processing.


Output devices :

It is output device. The name of our monitor is CRTVDU ( Cathode Ray Tube visual Display Unit). A CDU normally consists of 25 rows and 80 column .Some of the populary used monitor are:
Monochrome,HGA (Hercules Graphics 750X 350 Dots),EGA (Enhanced Graphics adaptor)
,Printer,plotter etc..

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