Page 43 - FUNDAMENTALS OF COMPUTER

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NPP Computer Basics and Windows Fundamentals 43

Keyboard Functions H$s~moS>© Ho$ H$m`©
Following functions are performed by key- H$s~moS>© H$m n[anW {ZåZ H$m`© H$aVm h¡:
board circuit:
1. Sensing a key. 1. {H$gr Hw§$Or H$mo nhMmZZmŸ&
2. Giving binary code for key. (Encoding) 2. CgHo$ gmnoj ~mBZar g§»`m àXmZ H$aZmŸ&
3. Transmission of binary code to computer. 3. Bg ~mBZar H$moS> H$mo H$åß`yQ>a H$mo XoZmŸ&

Types of keys Hw§${O`m| Ho$ àH$ma
There are different types of keyswitches H$B© àH$ma H$s Hw§${O`m± Cn`moJ _| AmVr h¢ Ÿ& BZ_|
used with keyboard. Commonly used are as {ZåZ _hËdnyU© h¢…
follows:
1. Mechanical keyswitch. 1. _oHo${ZH$b H$spñdM
2. Membrane keyswitch. 2. _oå~«oZ H$spñdM
3. Capacitive keyswitch. 3. Ho$no{g{Q>d H$spñdM
4. Hall effect keyswitch. 4. hmb B\o$ŠQ> H$spñdM
5. Reed relay keyswitch. 5. arS> [abo H$spñdM
Two-key Lockout Technique Qy>-H$s bm°H$AmD$Q> VH$ZrH$
In this technique when two keys are O~ Xmo Hw§${O`m| H$mo bJ^J EH$-gmW X~m`m OmVm
pressed, only one key is recognised. When the h¡, Vmo Omo Hw§$Or nhbo X~mB© OmVr h¡, Cgr H$m H$moS> A§Xa
first key is released then only next key is
recognised. OmVm h¡Ÿ& bo{H$Z nhbr Hw§$Or na go hmW hQ>mZo na hr
Xygar Hw±$Or H$s nhMmZ H$s Om gH$Vr h¡ &
Two-key Rollover Technique Qy¥>-H$s amobAmoìha VH$ZrH$
In this technique when two keys are Bg {d{Y _| XmoZm| Hw§${O`m± nhMmZr OmVr h¡ & O¡go
pressed, both are recognised. e.g. Ctrl+S, Shift+C Ctrl + S, Shift + C Am{X Ÿ&
etc.
N-Key Rollover Technique N-H$s amobAmoìha VH$ZrH$
In this technique codes of more than two Bg {d{Y _| Xmo go A{YH$ Hw±${O`m| Ho$ H$moS>²g EH$
keys are entered to perform an action. e.g. gmW H$åß`yQ>a H$mo {XE OmVo h¡ Ÿ& O¡go Ctrl + Alt + Del
Ctrl+Alt+del. All three keys are recognised.
H$aZo go VrZm| Hw§${O`m| Ho$ H$moS> H$åß`yQ>a _| OmVo h¢ Am¡a
H$åß`yQ>a [añQ>mQ>© hmoVm h¡ Ÿ&
Scan Code ñHo$Z H$moS>
In some computers the encoder circuit just Hw$N> H$åß`yQ>g© _| EÝH$moS>a H$m n[anW Ho$db ñHo$Z
gives a code corresponding to a key pressed. H$moS> XoVm h¡Ÿ& H$åß`yQ>a H$s _o_moar _| ñHo$Z H$moS> OmVm h¡Ÿ&
This code is called scan code. There is a pro- H$åß`yQ>a H$s _o_moar _| EH$ àmoJ«m_ {bIm hmoVm h¡, Omo Bg
gram written in computer memory called Key-
board translation program, which gives char- ñHo$Z H$moS> H$mo Ho$aoŠQ>a H$moS> _| ~XbVm h¡Ÿ& Bg àmoJ«m_ H$mo
acter code for the scan code. H$s~moS>© Q´>m§ñboeZ àmoJ«m_ H$hVo h¢ &