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Input Devices Post

Keyboard Short Note ( Categories Of Keys | Functions of Non-printable Control Keys)

Upload time : 2018-10-31 14:26:41

Category : Input Devices


- The most common input unit is a keyboard used for manual data entry.

- It is called QWERTY keyboard because these are the first six letters in third row from top.

- The arrangement of letters was standardized for mechanical typewriters in the last century but has continued as most typist are used to it and there is unwillingness to change.

Keyboard consist of the following major categories of keys :

- Letter keys: these are the 26 letters of English alphabet arranged as in a typewriter.

- Digit keys: there are two sets of digit keys; one on the second row from the top of the keyboard just as typewriter, and the other is numeric keypad at the bottom right which allows quick entry of numbers with the fingers of one hand.

- Special character keys: these are characters such as <,>,?,/,{,},[,],(,),.!,@,#,$,%,^,&,*,-,+,=,_. Most of this printed when shift key on CPU is pressed down and the key on which it is written is pressed.

- Non-printable control keys: this are used for backspacing, going to next line, tabulation, moving the cursor up or down, insert, delete characters etc. There is also a spacebar at bottom for leaving space.

- Function keys: these are labelled F1, F2, upto F15 and when pressed invoke programs stored in the computer.

Functions of non-printable control keys are listed below :

- Backspace key: this key backs the cursor to the previous character and deletes the current character. If it is pressed 3 times the 3 previous characters are deleted.

- Enter key: at the end of a line of typing, this key is pressed to go to next line.

- Arrow keys: moves the cursor up, down, back and forward.

- Tab key: moves the cursor to the next tab stop.

- Shift key: when kept pressed and a letter key is pressed, the upper case letter is printed.

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