HARDWARE COMPONENTS

HARDWARE COMPONENTS OF ICT

In this section, the focus is on what is termed hardware – the components of ICT

like the computer itself, storage media, and input and output devices.

Computers

The computer is a universal information processor. In theory, any kind of information processing can be done on any computer but, in reality, this is not true. A specific task for a specific computer may require too much time, or the computer’s memory may be too small. Computers process information in the form of electric signals. In other existing technologies, simple information processing can be done also in the form of air or liquid streams. There are attempts to produce computers that use light processing, or biochemical mechanisms similar to that of living organisms, but these approaches are at a premature stage.

CPU

Information processing is done by computer hardware. The most important components of computers are (electronic) semiconductors, similar to the components of radio or TV, but much more sophisticated. The number of electronic elements inside these components can be counted in millions. These elements are joined together to form integrated circuits (IC), commonly referred to as microchips, or simply chips. The core device in any computer, called the central processing unit or CPU, does all information processing. Today the CPU occupies a metal box in which you can see dozens of integrated circuits, wires, and cables connecting them. (Yesterday’s computers were much bigger and occupied a full room, or even a whole building.) The main IC in the CPU is the processor itself, which does most of the active task of processing, including adding numbers, comparing strings of symbols, sending information to memory (see below), retrieving it from memory and, very importantly, reacting to signals from the outside. The work a computer depends not only on its constitution as an electronic device, but also on the information stored in it or that it receives while in operation. This information can be considered as instructions that tell the computer what to do, and is called software. Information is stored, transmitted, and processed in the form of strings of zeros and ones. The input of information into a computer usually involves the transformation of images or sounds into digital and discrete strings. The output involves the reverse transformation. These components of hardware and software responsible for these transformations and making them perceptible to the human senses, are called  interfaces. Computer information is stored in special types of IC, called storage or memory chips. A computer’s speed is an important factor in its performance. It is measured in MHz, which refers to the number of changes inside a computer that can take place in one second.

Monitor

An important component of any modern computer used by a human being (and for this reason called a  personal computer), is the  screen or monitor. Monitors not only display information but can also support direct interaction. For example, if you need to make a technical drawing of a particular detail with a computer, you move your hand equipped with one of many input devices (see  Peripherals below), to create a line or activate a detail on the screen. The whole system of using physical movements to manipulate information and present this manipulation in intuitive screen images is called graphical user interface or GUI.

Connections

The CPU is connected with other ICT devices via communication channels. The most common communication channel is a cable plugged into a computer at one end, and to another device at the other end. The cables and sockets can cause problems, including incompatibility of sockets in the case of connecting your computer to a local telephone line abroad. A popular alternative to cables is wireless (radio-frequency or infra-red) connection. To simplify the graphic presentations, we do not include cables in the pictures, and say more about these connectors in the sections that follow.

Computer sizes

Computers that are placed on the desk of a clerk, student, or teacher are called desktop computers. Sometimes, however, the computer itself is placed under the desk with the monitor and keyboard on top. These computers usually weigh several kilograms, with the monitor usually being the much heavier component. Other computers are portable or mobile. Their weight and size permit them to be carried comfortably. Computers of a size and weight of a large notebook, which is easy to carry, are called  notebooks (formerly,  laptops). Today’s notebooks weigh as little as 1–4 kg. Computers the size of one’s palm, and weighing less than 1 kg, are called palm computers, handhelds, or palms. All such computers are called personal computers, or PCs, because they are intended for individual usage. CPUs today are very small. We can say that for most school applications the size of a typical CPU is not a limitation. On the other hand, in some classroom situations, the size of the whole computer matters. If we place a monitor on a student’s desk, it must be large enough to be comfortably visible, yet small enough to leave space for student work.

Energy for computers

Electricity is needed to run a computer and its related devices. The power consumption for a desktop computer is typically 100–500 watts. In many countries,this resource is widely available, but in others it is still a problem. For them,alternative power sources such as solar batteries, wind generators, and accumulators (rechargeable batteries), as well as UPS (Uninterruptible Power Supply),should be considered in the planning of ICT implementation. Solar batteries, for example, cost a few dollars and can supply a palm computer with energy, provided they are exposed to sunlight a couple of hours a day. Portable computers can use the same power line as desktop computers. However, it is much more convenient to have a portable computer that can function, for a while at least, with rechargeable batteries. These can support the computer for a few hours, and then need to be recharged from a power source. In the best cases, recharging takes much less time than the computer needed to use up its power, and recharging can occur while the computer is in use. A bad aspect about accumulators, apart from their weight and considerable cost, is that, if used intensively, they last only a few months. Even in the best cases, a rechargeable batteries’ life is much shorter than the life of the computer itself. In many cases, the modern processors that have appeared over the last few years require more energy to run than the older ones. Roughly speaking, every action of the CPU needs a minimal amount of energy to be used. If the processor works faster, the same amount of energy is used in a shorter time. As the computer runs, this energy dissipates in the outside environment in the form of heat, and so computers come equipped with special cooling mechanisms like fans.

Peripherals

For the best utilization of ICT in education, a teacher needs a wide range of devices connectable to a computer, and these are referred to as peripherals. The major categories of peripherals are devices for:

• Input: alphanumeric keyboard, musical keyboard, microphone, tape- recorder, tablet and stylus, scanner, digital photo camera, video camera, sensors, and probes.

• Output: monitor, printer, projector, headphones, speakers.

• Control: motors, lights for robotics construction kit, and sensors.

• Communication: modems, communication lines, satellite and local network equipment, and wireless networks.

Having a wide range of peripherals for educational and general use is more important in a school than the number of computers. We consider these categories of peripherals in a little more detail in the sections that follow. Different components of a computer as well as peripheral devices need tobe connected via channels for information flow. In most computers today,cables do this, but wireless connection is increasingly possible as well, which then requires, of course, that the device has its own source of energy (usually,power line or batteries).

Storage

Information is stored in integrated memory circuits or memory chips in the computer’s CPU. However, there are other ways to store information. These other means differ in capacity (the amount of information they can store) and access speed (how fast the information can be retrieved). Stored information can be retrieved and, in some cases, changed. Read-only memory (ROM) means that the user cannot change any retrieved information. In the opposite case, we talk about rewritable memory, stored on a computer’s hard drive or on portable discs. The cost of storing information is constantly and rapidly decreasing. The key storage devices currently are flash cards, magnetic tapes and discs, and optical discs.

Flash cards

Additional memory chips – so-called flash cards – can be easily inserted into and removed from the body of current computers. They do not require batteries to keep information stored. The capacity of one card today is in the range of 10MB to 1GB and access is fast enough for most applications. Flash cards are widely used in digital cameras (see Cameras below in this chapter) and other applications. They are rapidly replacing discs (see below). Some versions of ROM cards are used in game consoles (where they are also called cartridges).

Magnetic tapes

Magnetic tapes, similar to those used in tape-recorders, can be used for storing digital information as well. To read or write information on a tape, a special device similar to a tape-recorder is used, called a tape drive. The drive can be external to a computer or placed inside the CPU box. The capacity of a tape can be up to 10 GB and even more. Access speed, however, is slow, which can be critical for certain applications, though this is less important for most school uses. Magnetic tapes are rewritable.

Magnetic discs

The idea of disc storage can be traced back to gramophone recordings at the beginning of the 20th century.  Information on those discs was permanently stored in the form of small mechanical (geometrical) changes in the surface of the disc. Some of today’s versions of disc storage use a magnetic principle similar to tapes, and these discs are rewritable. Discs with the capacity of about 1MB are also called diskettes; you can insert them into a drive (disk-drive), or remove them. It may take up to a minute for a computer to read from or write to a diskette. Newer discs have a capacity of up to 1GB. The competition from flash cards (see above) is strong. Discs with even greater capacity are mounted on their own drive, and these are usually called hard discs. Their capacity is in the order of 10GB to 1000GB. The access time for hard discs is fast enough for most applications.

Optical discs

Information can also be stored on a disc as an optical trace. This principle is exploited in  compact discs (CD), widely used now for storing music. The capacity of a CD-ROM is approximately 1GB. Access speed may not be fast enough for some applications involving sound or moving pictures. To address this problem, observe the different speeds marked on CD-drives: 2x, 6x,... 48x... A newer form of CD-ROM is called digital versatile disc or DVD, which looks similar to a CD but can store 10GB or more information. Rewritable CDs and rewritable DVDs have appeared in recent years. Human movement as input The most common way to input information into computers is by human hand through a variety of devices: keyboards, the mouse, graphical tablets, and touch screens.

Keyboards

The most important input device for computers currently is the keyboard, which serves mostly for text input, and, to a large extent, imitates the keyboards of type-writers. The computer has many advantages over a typewriter, even apart from its more sophisticated software and other applications. The first of these is how easy it makes it to change, delete or insert any word or phrase. The next is the ability to copy any text fragment and to move it as a solid object anywhere with- in a text, or to another text, usually referred to as  cut-and-paste. Touch-typing (not looking to the keyboard and using 10 fingers) is a useful skill in the educational context today. Students can learn touch-typing faster than handwriting; they can type faster than they can write; and the results are more attractive and much easier to edit and revise. Extensive work with the keyboard, however, sometimes causes muscular tension and requires special precautions, which students and teachers rarely take (see the section below on  Health problems associated with computers). Newer ergonomic keyboards are becoming more prevalent, as is the use of alternative methods of writing such as script and speech recognition. Different arrangements of characters on the keyboard could make typing more effective. A radically new tool, called the Twiddler, is an ergonomic handheld, touch-type keypad designed for chord keying, which means that like a piano you press one or more keys at a time. Each key combination generates a unique character or command. Because of resistance to change, widespread adoption of these tools does not look probable. Keyboards of notebooks are usually built into the book. Keyboards are not usually built into palm computers. Sometimes a keyboard is represented by a screen image on which you type by touching keys with the tip of a special pen. Sometimes, lightweight unfolding keyboards are used for palm text input.

Musical keyboards

Musical keyboards look like a traditional piano or modern rock-group synthesizer keyboard, only smaller. Attached to a computer, this peripheral can be used far beyond the imitation of a piano. The standardization of digitized sounds of most instruments in MIDI (Musical Instrument Digital Interface) allows students to play and even to compose musical pieces performed by different instruments or an orchestra, and immediately hear a performance of the piece by those same instruments. Notes input with a musical keyboard can then be edited with a mouse. The avenues for students’ musical self-expression are in this way dramatically enlarged.

Mouse and its alternatives

To manipulate screen objects, you need to  point, choose, grab, and  open  them. In today’s computers, these operations are usually done with a special instrument, which indicates an object on the screen and moves it as a solid body. This instrument is called a mouse, a handheld, traditionally grey, plastic body that you move on the table-top, which is usually covered by a small mat called a mousepad, designed to improve the movement of the mouse. As you move the mouse, a small object (an arrow, for example), called a cursor, moves on the screen, mimicking the mouse’s movements on the table. The mouse has buttons that help you to extract, pick up, and manipulate objects. You move the cursor to an object and click a button; the object now is attached to the cursor and can be moved. If you click another button, the object opens up. These actions are part of GUI or the graphical user interface. There are other devices to transform movements on screen into information manipulation inside the computer similar to the mouse. They all act similarly, but the physical movements of a human hand working with them can be quite different: A handheld mouse, not lying on the table, can have a small gyroscope inside, and is useful when you show something to others on a big screen.

A trackpad is a small panel (about 3 by 4 cm) over which you move your index finger to control the cursor.

A  trackball is a ball about the size of an egg embedded into a panel, which you can rotate.

A joystick is a small lever (as in a car transmission gearshift) used mostly in computer games. There are also very small joysticks inside some keyboards called trackpoints, which you can push and deflect with your finger. These are also used as the mouse part of the Twiddler mentioned above, where the trackpoint is controlled with the thumb. Wireless mice that have no moving parts are more reliable and have become more popular. Among them there are handheld mice that you do not place on a table but move in 3D space.

Graphical tablets

Another type of input is to draw or write with a pen. The difference between a computer pen or stylus and an ordinary one is that the computer pen moves over a special surface called a graphical tablet, and the trace of the move can be represented on screen. The computer can also measure levels of pressure. With appropriate software, a computer can imitate almost all existing drawing techniques and create some exciting new ones. The computer is very useful for tech- nical drawing – now, mostly part of computer-aided design or CAD.

Handwriting

The most effective way to start written communication for children (and adults) is to have them type on a computer. But handwriting is still a popular and useful skill. Consequently, handwriting recognition, which immediately transfers hand-writing into block letters on the screen (and text in computer memory), is a valuable supplement to keyboarding, and sometimes a major input technique (for example, in certain kinds of environmental observations). With palm computers, you can write text that can be recognized by the computer using a special stylus. Handwriting and drawing by hand on a large whiteboard can be done with a computer also. In this case, you write or draw on the board with a special mark- er that is traced by an infrared or ultrasonic detector.

Touch screens

The devices discussed above are intuitive enough but nev ertheless separated from the objects on a computer screen. Another promising type of device combines seeing with touching, allowing you, for example, to outline an object on the screen with your finger and then move it to a different position with the same finger. This is already achieved with touch screens. A finger cannot indicate a very small object on a screen. However, this limitation can be relaxed by using a stylus on the screen (a kind of pen or pencil designed for this kind of interaction). Touch screens can work well and are more intuitive for small children, but are not widely used. One reason for this is their cost, which is higher than an ordinary screen and mouse. Nevertheless, they are the most popular devices in most information kiosks and in palm computers. Further options for human movement input are discussed below under the sub-section on major trends in ICT.

Visual input

In the mid 19th century, photography was invented as a means of fixing and storing visual information in an external medium using a chemical process. In the 1930s, devices were introduced that transform visual information into electronic form for immediate transmission via electromagnetic waves: TV technology. In the 1950s, simultaneously with computer technology, methods to record and play back analogue TV and still images appeared: the video tape. At the end of the 20th century, digital photography and digital TV became an integral part of computer-based ICT.

Cameras

Cameras store or transmit visual images. The photographic camera stores a still image on photo- graphic film for further chemical development. Instead of putting an image onto a film, a digital camera places it in the computer’s memory, or in the memory of the camera for transmission to a computer for storage or direct printing afterwards. An interesting application of digital cameras is the projection of a small image (such as a bug, for instance) onto a large screen. Nowadays, digital cameras can store video images also.

Scanners

Scanners look very like copying machines, but are smaller and usually work more slowly. Instead of producing a paper copy of an image, a scanner transmits an image in digital form to a connected computer. Scanners can be used to transform information from a paper source – a text, an image from a book, a drawing, or a photograph – into a digital image. Additional devices can be used for scanning 35mm slides. There are also handheld pen size scanners that you can move over a line of text or a bar code for input or storage inside the scanner. Special 3D (three dimensional) scanners can produce scanned images viewable from different angles.

Optical character recognition

A special situation occurs when an image is a text (or text combined with graphics) in printed or hand-written form. In this case, the image of the text can be transformed (converted) into a computer text file that can be processed as one does other texts in the computer (e.g. insert a phrase; change a shorter name to a longer one, and so on). This process of transformation from picture to text uses sophisticated software called Optical Character Recognition (OCR).

Aural input

As with visual information, non-electronic, that is mechanical technologies, were developed first to store sounds. Then, electronic technologies were developed to transmit sounds (telephone, radio), followed by electronic media and tools to store sounds (tape-recorders).

Microphones

Microphones transform sounds into electric signals for storage or transmission. There are different types of microphones and different ways to work with them:

• A microphone can be fixed in a stand in front of a speaker who is standing or sitting.

• Speakers can hold a microphone in their hand.

• A lightweight microphone can be attached to a speaker’s clothes.

Information converted by a microphone into electrical signals can be transmitted via a wired or wireless channel to other devices.

Sound recording

Sound can be recorded with a usual tape-recorder. To process sounds with a computer, you need to convert them into digital form. A microphone can also be plugged into a computer directly. In this case, the computer serves as a recorder. Digital recorders to store sound in digital form using flash cards are becoming increasingly popular. Modern computers can easily store hours of speech. Music recordings, processed and compressed by computer (in MP3 format, for example), occupy very little memory. The spread of this process, on CDs and through the Internet, is changing the recording industry and affecting mass culture.

Speech recognition

During the last few years, software has been developed that allows a computer to transform human speech into a text file similar to the conversion of handwriting as discussed above. This transformation can be done with a level of quality that

makes it adequate for educational applications, and is useful, for instance, in learning English.

Sensors for input

Measurements of the environment like temperature, humidity, acceleration, or magnetic field, can be input to a computer-linked device called a sensor. A sensor generates an electrical signal that is then usually transmitted to a computer via an interface. More sophisticated sensors can measure such parameters, store, and display them, even if a sensor is not connected to a computer. This can be done by individual sensors or by what is called a data logger, a special device or small box to collect and store data. The content of measurements can then be transferred to a computer. Very promising in school education is the growing number of sensors – from those that measure acid rain and heavy metal oxides ratio in potable water to the Global Positioning System (GPS), which allows anyone to find geographic coordinates and related information on the earth’s surface.