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Keyboard. Topics to be covered. Introduction History of keyboard Types of keyboard How keyboard works Inside the keyboard Connecting the keyboard to the computer . Introduction. Two Device
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Topics to be covered • Introduction • History of keyboard • Types of keyboard • How keyboard works • Inside the keyboard • Connecting the keyboard to the computer
Introduction Two Device 1.Input Device 2.Output Device Keyboard Monitor Joystick Printer Mouse Sound system Light pen • Use in data base, MS Word,
History of keyboard • Evolution of adding more keys • 101-key Enhanced keyboard • 104-key Windows keyboard • 82-keys Standard keyboard • 108-keys Extended keyboard • Multi-Media key supported K/B
Basic parts of keyboard • 4 Parts of keyboard ->Typing Keys ->Numeric Keypad ->Function Keys ->Control Keys
Typing Keys • Typing keys section of Key board • Lay out same as typewrite • This Lay out know as QWERTY • Design of Typing keys
Numeric Keypad • Part of natural evolution • Use in Calculator, type numeric data • 17 Keys was added
Function Keys • Function keys r F1,F2…..F12 • Arrange in row along the top • Use in operating system
Control Keys • Control curser and screen • 4control keys arrange T shape , • Home, And, Insert, Del, Pgup, Pgdown, Esc, Inc
Types of Keyboard • Rubber dome mechanical • Capacitive non-mechanical • Metal contact mechanical • Membrane mechanical • Foam element mechanical
Rubber dome mechanical • Popular switch technology • Each key sit over flexible rubber dome • When press the key dome press by switch
Metal contact mechanical • Metal contact & Foam element ,s Design same • It has spring loaded key with line of metal • When press key metal line connect 2 part of circuit • Foam element has small bubble foam • which is between metal line & switch • Metal contact & Foam element r not same in use
Membrane mechanical • Membrane switches similar rubber dome • It has rubber sheet with bubble for each key
Connecting keyboard • Keyboard connectors • 6-pin PS/2(USB) connector • In laptop internal connected 1.=Ground 2.=+5v 3.=Data 4.=Clock 5.&6.=Not use
Working of Keyboard • When the key is pressed • The interrupt is generated and send to the processor • This can be decoded by the IVT (interrupt vector table) saved in first 1kb of memory • Then appropriate function is performed
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