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• Keyboard is a basic computer input device. Its task is the communication with PC by help of entering characters and numbers. For those who know writing on typewriter or want to replace a typewriter with PC and printer, the keyboard will not be unknown. This article was written for users who want to get more detailed information about keyboards important in case of buying a new keyboard or troubleshooting. For such users who just need basic description of keyboard I recommend rather this article: "Basic description of keyboard and some tips for using". 

• Despite the common keyboards belong to the cheapest computer components, it is not such an easy part as it could seem. We can divide keyboard into 4 basic parts: 1. Key cap, 2. Mechanism enabling press and return of a key 3. Electronic mechanism recognizing press and return of a key, 4. Microprocessor recognizing and reporting pressed keys. 
  

PC keyboard evolution

• Over c. 20 years of PC using the IBM company designed 3 types of keyboards from which the last one was adapted by Microsoft for Windows.

• 1. XT and 83 keys (not produced any more)

• 2. AT and 84 keys (not produced any more) - it was progressively and completely replaced by extended keyboard. It was incompatible with XT keyboard (but there also used to exist keyboards with the possibility of switching between XT and AT).

• 3. Extended AT (Extended Keyboard) and 101 keys (in shops you will find them very rarely - replaced by keyboards for Windows).

• 4.a Extended AT for Windows and 104 keys - Over against clasiccal keyboards this one has extra keys for: 

Windows - displaying of the Start menu, easy moving by help of cursor keys and confirming with Enter key (you´ll value especially in case your mouse doesn´t function or when you need to look into the Start menu quickly). Besides the press itself there are also hot keys used (Win + R - Start from Start menu, Win + E - Starting Explorer...) 
Application - displays local menu (the same function as the left mouse button) 

Special keyboards 

• 4.b  Extended AT - Ergonomic - Ergonomically shaped and variously "bisected" keyboards are designed for your hands and their natural position when typing. The typing is then more comfortable and so protects your health for which the artificial position of sitting at your computer or typing are not too wholesome. Unfortunately, for most people who are used to typing on typewriters or have long-time experience with classical keyboards, getting used to another shape of the keyboard is sometimes difficult. The best known and one of the first such keyboards probably came from Microsoft under the name Natural Keyboard.

• 4.c  Extended AT - Multimedia - usually 107 - 120 buttons - Multimedia buttons can have different functions - the most frequent serve: 1. to control CD or a multimedia player (buttons such as Play, Pause, Stop, Next forward... - usually valid only for a limited amount of multimedia players - most often Windows Media Player and Winamp), 2. ACPI (Power, Sleep, WakeUp) and 3. programmable buttons. Some multimedia keyboards contain an easy microphone and speakers. 

• 4.d  Extended AT - Internet - Indeed, it is an answer to or a combination with a multimedia keyboard equipped with several buttons for easier access to Internet (by help of one key you can start up your Internet browser, mail client, move in dialogs, browse in sites or go to search service or your favourite site...) 

• 4.e  Extended AT - Security - Keyboards equipped with smartcards readers or with biometrics (finger-print sensing), e. g. Biometric Keyboard by Keytronicsor Security Keyboards by Silitek).

• 4.f  NTB - In many cases it is the same as the extended keyboard, but without noticeable numeric part. You can activate the numeric keys through a function key at the expense of some alphanumeric keys. For common typing the numeric keyboard is set up as inactive. Some NTB keyboards are diminished which can cause some difficulties to some people.

84 kláves u NTB

• 5.b  Extended keyboards for NTB - Typical example is a numeric keyboard connected to one of the ports.

• 6.a  Industrial - Special types of keyboards not only for common computers - they are especially designed for industrial environment, where it is necessary to protect the keyboard from dust, water and chemicals. There usually helps a special plastic coverings for particular keys or a foil covering the whole keyboard. To see the keys properly the coverings are coloured or the keys are lighted. 

• Special - Almost all kinds of keyboards belong to this category except the classical, primarily keyboards for NTB, security, industrial and additional keyboards for NTB. All those keyboards are mostly based on extended AT keyboards and differ in shape or in some additional keys available thanks software.

Electronic mechanism recognizing press and return of a key 
(Switch activation mechanism)

• We can divide them into mechanical and capacitive or contact and non-contact. In case of the first one (mechanical) you have to switch a circuit for the key recognition, in case of the other one (capacitive) the capacitance is measured. 

• 1. a - Mechanical - Keyboards using electric and mechanic switches. There is an iron spring used to cushion. It is noisy, complicated and expensive to produce. They are often replaced by membrane switches.

DELL AT101W - FCC ID GYUM90SK

• 1. b - Conductive Rubber - There is a conductive rubber strip on the punch in the middle of the key. After pressing the key it connects the contacts on the printed circuit (or on the printed foil) . 

Examples

The reentry mechanism of the Mitsumi keyboard is formed by a rubber cap under the key 
(it can be a spring in other keyboards)

Mitsumi KPQ-E99ZC-13 - FCC ID CMYKPQ6987 

(alternative principle - BTC 5140 - FCC ID E5XKBM10410)

• 1. c - Membrane - The classical membrane keyboards you will most often find in microwave ovens, photocopiers, mobile phones and similar devices in which the keys of the membrane keyboards are connected into a whole - but in computer keyboard it is not so. There are another switching elements added to the membrane in the computer. Today, the most used solution is a keyboard with a rubber membrane (Rubber Dome). The base - electronic membrane (dome) - containing three foil remains: 1. a foil printed with conductive tracks and sensitive points under keys, 2. a separation foil with holes under the keys ensures that the sensitive points connect only when they are pressed, 3. a foil printed with conductive tracks and sensitive points under keys. The rubber membrane is formed by rubber domes under each key - a little rubber bulge in the dome under the key presses the membrane's contacts and the rubber dome returns the key back to its initial position. An illustration of the membrane keyboard's interior you will find in the article Logitech Deluxe Access™

• 2. a - Capacitive - There is no mechanical switch used, there is just the capacitance measured between contact pads under the key - when the contact pads move against each other this capacitance changes and is evaluated as a key press. It is interesting that the key need not touch the sensitive element - just approaching is enough. Touchpad works on this principle, too. These keyboards you will meet very rarely. Their disadvantage can be the price but for which you get the highest length of life - up to 30 million keystrokes. These keyboards are very difficult to repair.

• New keyboards often use combinations of several technologies. 

Terms

• Keyboard Microprocessor - Keyboard Controller - Microprocessor evaluating and recognizing press and release of the key on the keymatrix. Besides that it ensures the typematic rate and bounce filtering. 

Besides the microprocessor in the keyboard the keyboard's controller

 is also integrated as a part of the chipset on the motherboard.

• Keycap - the plastic button itself. We can also use the term "key", however, we should say that a key = plastic button + mechanism sensing the key press. By help of the print you can easily recognize what character will be written onto the screen (providing right SW setup).

• Keymatrix - Keymatrix consists of conducting paths and is organized in x,y axis system enabling to assign a unique code to each key.

• Scan code - key code sent to the keyboard's control chip. This code is different for each key. The code is not dependent on one character of the keyboard and so the key is not dependent on language settings and OS.

• Character code - Each letter and character is represented by a code, e. g. ASCII code. E. g. - if you want to write a character by help of ASCII code you just press Alt key and code of the desired character on the numeric keyboard (see Basic description of keyboard)

• ASCII code - Standard code diagram that assign a unique number to each character and symbol for easy identification and information transmissibility between computer systems (values: 0 - 255).

• Bounce - There can appear some low vibrations when pressing a key which can the keyboard's microprocessor register as multiple press.

• Frame - a frame for fixing the membrane keys. The keyboard's upper covering usually works as the frame for fixing the keys, as well.

• Plunger - In the membrane keyboards the plunger is represented by a bulge hidden inside the dome under each key.

• Return Spring - replaced by a rubber membrane in more recent keyboards.

• Hot keys - assigning a function or an action to a particular key or combination of keys - see Hot keys) 

Parameters

• Switch Travel - It is differential value from the initial key´s position to the value after pressing. The value is usually cca 2.5 - 7 mm and it is an important reading for defining writing easiness level. A lot of people prefer an easy press of keys, while the others rather a stronger press.

• Operating Force - force necessary to make for pressing a key. Together with the "Switch travel" they influence if you have to press the key softly or by help of more power (touch or press?).

• Operating life

• Contact - Used switch technology

• Character printing Method - the way of printing the keys. It is important - the print has to hang on because it is very strained and sensitive to outwear. Laser print is most frequently used.

• Tactile feedback - the feedback after pressing a key which is no value but the user's feeling when pressing a key. The feedback is influenced by the frame and the return mechanism power.

• Power - important especially in keyboards for portable computers. Usually 5Vdc and 50 - 500mAh

• Peak load before make - power necessary to influence a key (cca 50 +/- 15g)

Kinds of connectionDIN (DIN5)

• DIN (DIN5)  - Connection through an older rounded connector with 5 outputs. 

• PS/2 (MiniDIN6) - Today, the most widespread and most suitable connection - connection through a little connector with 6 outputs. It looks similarly to the PS/2 connector for mouse - it is easy to confuse them. It is sometimes marked with colour in more recent computers (not all the producers do it). In ATX computers the keyboard is always nearer the motherboard (computer's side).

• USB - to connect a keyboard through USB you often have to activate USB Keyboard support in the BIOS setup. If you do not do it your keyboard will not work: under DOS, in OS option in the Start menu in Windows 2000 and at start of Windows 9x (no F8, F5, Esc...). But there is one advantage - in case you do not have enough USB ports there exist some keyboards that have more USB ports inside (then the keyboard functions as an adapter for connection of other devices).

• Wireless - besides the wireless connection of mice there also exist keyboards connected by help of radio or infrared receiver on PS/2 or USB. The technology is the same as the one in case of mice. If you want to know more go back to mice.

• In case you buy a keyboard with a wrong connector you can buy some of the reductions (PS/2 - DIN or DIN - PS/2) - you then needn´t change your keyboard.

Drivers and Installation

• For most keyboards you do not need any driver, but for multimedia and special keyboards you need to install some supporting software allowing extended functions. E. g. for the Logitech keyboard it is iTouch software supporting programming and multimedia keys (Logitech is only an example, I do not want to build this company up - most multimedia keyboards made by smallish producers work equally).

• Installation of keyboard is nothing difficult, however, there exist cases when it is necessary to configure the keyboard. Most frequently, it is a keyboard´s setup for particular language environment. Why? Besides various languages there also exist various keyboard layouts. Some differ in details, the others differ radically.

Keyboard layout - Language support 

• Physical keyboard's look - I just want to remind that keyboards can sometimes slightly differ in size, but mostly their sizes are standardized. So, you can only encounter a problem relating to the keyboard's size in portable computers of which keyboards are a little bit smallish then the classical. 

• QWERTY (" qwerty ") - Layout for typewriters and now also for computers made at the end of the 19. (pozn.: 20?) century. The name is derived from character order in the first line of the alfanumeric characters.

• DVORAK " ',.pyf "- More effective competitive QWERTY design of keyboard which opposed the keyboard's wrong layout. It was designed by August Dvorak and William Dealey in 1935. This layout takes into consideration the most frequently used keys and easy and quick changing of hands and fingers. Unfortunately, there existed and still exists a counter-argument that the QWERTY layout is too known and too widespread.

Some characters can be differently marked on the keys, then you just use stickers or remove the key and replace it with a rightly marked key. On the picture you can see transparent stickers designed for US keyboards (the stickers are also used for special keyboards where the alternative for the Czech language does not exist - it is a case of keyboards imported in few copies from abroad). 

• Example of differences between Czech and English keyboard - Y and Z - QWERTY is the English and QWERTZ is the Czech layout. Besides this little difference it also differs in the upper key line in the Czech layout where the letters with diacritics and some other characters are located. Under Windows you can easily switch between Czech and English keyboards. The common users usually use QWERTZ, while computer programmers use the English QWERTY without the Czech characters which they do not need for programming and they can also easily get to numbers and some characters. 

• Is the layout not important for you? Maybe not for you. In larger companies you can meet people of different nationalities who sometimes need to write something in their language - then the characters can radically differ (e. g. for Greece, Russia, Japan, .....). In Windows you can, e. g. for French or German choose from 5 different keyboard settings, for Spanish it is 20 different settings (there is a lot of countries where the people speak Spanish and each of them can require some particular changes which are for those people essential).

• Program buildup can also be used - they enable using of a foreign keyboards (it is advisable to use a localized version).

• Character map  - The character map belongs to the Windows accessories. This map enables an easier orientation in the characters with the possibility of their inserting (even if you will not find them on your keyboard). Their amount depends on the installed and chosen font type. In exceptional cases you can insert fonts of different languages, but for often typing it is suitable to find another solution (local settings, localized OS version, buildup for the keyboard's support...)

Colour

• The colour is mostly white or grey. A lot of people think that there do not exist other colours - but it is not so. The most frequent colour after grey is black or in specialized shops you can find many keyboards of different colours.

• For most people the transparent keyboards are new. Through the transparent plastic cover you can see the keyboard's electronic, sometimes the keyboard also shines.

Keyboard's setup 

• Windows - In case you do not want to setup the writing speed in BIOS you can make it under Windows (Control panels\Keyboards)

• DOS - the typematic rate and the typematic delay you can setup by help of the mode con command (help you will gain writing ? - mode con /?) 

BIOS

• Typematic Rate Setting - you can switch on or off the manual setup of typematic rate. In case this is off (disabled) the setup is automatically selected (the most frequent selection).

• Typematic Rate (Chars/Sec) - Number of characters written in 1s. by help of holding a key (values: 6 - 30) - it influences the writing speed.

• Typematic Delay (Msec) - Time in milisec. for recognizing the repeated key press (values: 250, 500, 750, 1000)

• KBC Input Clock - On some MBs it enables to setup the speed of communication between computer and keyboard. The initial value is usually 8Mhz (possible options: 6,12, a 16Mhz).

• USB Keyboard Support - switches on the USB keyboard support. Without doing it you cannot use the keyboard in the DOS system, neither in the OS Start menu under Windows 2000 (in the Windows system itself the keyboard works normally). 

Cleaning

• By help of vacuum cleaner (Carefully!), compressed air or complete dismantling and cleaning by help of special detergents for electronics. The plastic parts you can clean with water, cleaning pads or special computer cleaners.

• Before you start buying expensive detergents and dedicate the necessary time, try to count if it is better to do this or to buy a new keyboard (usually the last one is cheaper and more suitable solution).

• Clean only a keyboard that is not connected to computer.

• Mostly you do not have to dismantle the whole keyboard, but just to remove the keys. But if you need to clean it really thoroughly, it is better to dismantle it. The way of dismantling is always a little different - usually the difference is in few screws on the bottom part. Some keyboard's screws are hidden under keys, stickers, rubber underlays or legs or plastic fittings. When you omit or do not recognize the mechanism you risk damaging of your keyboard. 

Problems with keyboard

• Damaged cable or connectors - Check if the cables are really and visibly damaged. The problem is often in the cable which has been pulled off near the keyboard or connector. Check the connector if there are all its pins.

• Wrong keyboard - It is also possible (try the keyboard on another computer or ask the HW supplier for help).

• Wrong port on the motherboard - try another keyboards on your computer (always switch off your computer between the changes).

• Confusion of connectors - the PS/2 connector for mouse and for keyboard are the same. Check if you are really putting the keyboard's connector to the keyboard's connector on the motherboard.

• Wrong reduction or extension cord - try to connect the keyboard to another computer first without reduction / extension cord. If the keyboard functions the reduction is wrong (or extension cord) or the problem is in the connector on the motherboard.

• Wrong layout - Mostly it concern the case of keyboard's layout variations for different national settings. Usually the keyboards are then equipped with stickers or are replaced by another.

• Locked keyboard - In older PCs it was possible to lock the keyboard on the front panel. If you meet such PC it is no problem to gain a key which was almost universal for all types. Today you will find such locking in the hard disk's mobile rack. New computer cases and MBs have this function very rarely.

• Letters - Replacement of the whole keys or sticking with stickers (for languages or in case of outwear)

• Damaged keyboard - the most often cause of a keyboard's damage is probably its outwear and polluting with food or drink. Sometimes cleaning helps but compared with its price the best is to change it for a new one.

• A blocked or a wrong key - A blocked key can cause that the keyboard seems to be damaged. But the solution is easy - just find the wrong key and replace it (sometimes it is enough to remove it and put it back or to knock it a little). Some of the blocked function keys can cause strange behaviour emulating viruses - some keys function normally, some cause running of a program or carry out some actions.

• Your health - See Logitech Deluxe Access(tm) 

 Others

• Switching computer by help of keyboard - only some PCs have this function of switching on the computer by help of combination of keys (it depends on the motherboard's support). This function must be setup in BIOS or by help of jumpers (the settings differ according to the type of the MB and producer). In case this function is on you have to know this combination, because the power button usually does not work (in some companies this is used as a security precaution).

• Two keyboards for a PC - In more recent PCs it is quite easy - just use a USB keyboard and a keyboard for PS/2. For older computers you have to use a switch for keyboards.

• One keyboard for several PCs - More frequent than several keyboards for a PC - usually a switch is used. The switch is device into which the cables are conducted from each PC, for which we want to use a keyboard. By help of a scroll switch we determine for which PC should the keyboard be used now. It is a suitable solution for saving space in servers and avoiding permanent connecting and disconnecting the keyboards. Who does not like even this solution I recommend some software for Remote Administration. 

• Keyboard switches - By help of switches you can connect up to 6 keyboards to a PC. Be carefull - you have to buy the right type of switch (when you want connection of several keyboards to a PC the seller will maybe wonder)!

• Short cables - For all types of keyboards you can buy extension cords (length limited and not apply for USB). 

• Note - Chinony - KU 2971 - USB and Samsung SEM-DC8UL - FCC ID E2XSEM-DT45 and Chicony - KB-7903 (ERGO) - FCC ID E8HKB-7903 

Tips for buying

• For users who work on the keyboard the bulk of the day also little details are important. The keyboard can seem too soft to somebody and too hard to another and someone else can say that the clicking sound of the keyboard is bothering. Someone cannot get used to an ergonomic keyboard and the other cannot live without it. The best solution is to go to a shop where they have a good assortment of keyboards and to try writing a while - then you will certainly make the right decision.

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