A desktop computer before is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware.
The figure below shows the most common hardware in a desktop computer system. Your system may look a little different, but it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.
Figure 4a: The Computer System
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The computer system components parts were described in chapter 2 of this book and almost all the components described are parts of computer hardware. In this chapter the computer hardware will be describe based on the computer hardware configuration which include both the directly visible and invisible hardware. This hardware configuration is as given in figure 4b below.
Figure 4b. Computer Hardware Configuration
Note: Computer Hardware can be divided basically into two; the CPU and Peripherals. CPU is made up of control unit, Arithmetic
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and logic unit and Main memory. While the peripheral is made up of Input devices, Output devices and Backing storage.
The components of computer hardware based on the diagram in figure 4b are the CPU and Peripherals (input and output units). Some of the peripherals were described in chapter two of this book.
4.2 Central Processing Unit
This is an integral part of system unit of computer system that made up of other components like; the main storage, the control unit and the arithmetic/logic unit.
Main Storage
The Main Storage contains two types of memory chips, named the Random-Access Memory (RAM) and Read-Only Memory (ROM). RAM is a memory that has the same access time for all locations. It is used to store data and program temporarily whenever they are needed in main memory. It is constantly being re-used for different data items or programs as required. Static RAM holds its memory so long as there is a power supply. Dynamic Ram (DRAM) has to be refreshed by reading and rewriting the contents very frequently. RAM is volatile, that is, the con-tents of RAM are lost when the power supply is switched off. ROM (integrated circuit) is used to store vital data and programs which need to be held within the main memory at all times. The contents of ROM are permanently set during the manufacture of the computer.
However, there are other ways of putting programs and data into ROM. Programmable Read-Only Memory (PROM) is a type of ROM that is manufactured as an empty storage array and is later permanently programmed by the user. Erasable PROM (EPROM) is a type of PROM whose data can be erased by a special process so new data can be written as if it were a new PROM. Arithmetic/Logic Unit (ALU)
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The Arithmetic/Logic Unit (ALU) consists of adder/subtractor, electronic circuit and working registers to which operands may be transferred during an operation. The ALU performs the
Arithmetic Operations
Data Handling Operations
Logical Functions.
The data to be processed are taken from main storage, stored in the working registers, processed and the results placed back in the main storage.
Control Unit
The Control Unit examines the individual instructions in the users‘ program one by one, interprets each instruction and causes the various circuits to be activated to perform the functions specified. Some of the functions of the control unit are:
It co-ordinates the various parts of the computer system to form a composite integrated data processing system.
It controls the transfer of data between and within the working stores as required by the program.
It controls input/output. Once the program controller has initiated a read/write operation, the control unit continues to monitor the operation to ensure that it is satisfactorily completed.
In time-sharing or on-line systems, the control unit co- ordinates the several concurrent peripheral operations while data is processed internally within the CPU.
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4.3 Peripherals Input & Output Devices
4.3.1 Input Device
Computer Input is the process of transferring data from computer- sensible media into the main storage of the computer. The equipment which converts data been captured on a source documents into machine sensible form is called an input device. The following terms are related to inputting data into computer.
Data Capture is the term used to describe the process of collecting data in machine sensible form at its source.
Data Collection is the term used to describe the process of recording the data on source document and subsequently converting it into machine sensible form for input to the computer.
Data Conversion is the process of transforming the data on source documents into machine sensible form before carrying out the input operation.
Type of Input Device
Direct Input Devices allow data to be input into the computer without any need for data conversion. Examples are: keyboard terminals, mouse, trackballs, scanners, joystick, bar-code readers, touch screens, OCR, OMR and MICR equipment.
Indirect Input Devices accept data from source documents and convert it into computer-sensible form for subsequent input into the computer. Examples are: magnetic tape, magnetic disk, compact disk and diskette drives.
Input devices can also be classified as manual or automated. Manual input devices include keyboard, mouse, trackball, joystick, bar-code readers, scanners, and touch screens. Automated input
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devices include MICR, OCR, OMR, magnetic stripe and smart cards.
Computer keyboard
A keyboard is used mainly for typing text into your computer. Like the keyboard on a typewriter, it has keys for letters and numbers, but it also has special keys like:
The function keys, found on the top row, perform different functions depending on where they are used.
The numeric keypad, located on the right side of most keyboards, allows you to enter numbers quickly.
The navigation keys, such as the arrow keys, allow you to move your position within a document or webpage.
Some modern keyboards come with “hot keys” or buttons that give you quick and one-press access to programs, files, or commands. Other models have volume controls, scroll wheels, zoom wheels, and other gadgets. For details about these features, check the information that came with your keyboard or computer, or go to the manufacturer’s website.
Figure 4c. Modern computer keyboard
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Three odd keys
So far, we’ve discussed almost every key you’re likely to use. But for the truly inquisitive, let’s explore the three most mysterious keys on the keyboard: PRINT SCREEN, SCROLL LOCK, and PAUSE/BREAK.
Print Screen (or PRT SCN)
A long time ago, this key actually did what it says—it sent the current screen of text to your printer. Nowadays, pressing PRINT SCREEN captures an image of your entire screen (a “screen shot”) and copies it to the Clipboard in your computer’s memory. From there you can paste it (CTRL+V) into Microsoft Paint or another program and, if you want, print it from that program. More obscure is SYS RQ, which shares the key with PRINT SCREEN on some keyboards. Historically, SYS RQ was designed to be a “system request,” but this command is not enabled in Windows.
Scroll Lock (or SCR LK)
In most programs, pressing SCROLL LOCK has no effect. In a few programs, pressing SCROLL LOCK changes the behavior of the arrow keys and the PAGE UP and PAGE DOWN keys; pressing these keys causes the document to scroll without changing the position of the cursor or selection. Your keyboard might have a light indicating whether SCROLL LOCK is on.
Pause/Break
This key is rarely used. In some older programs, pressing this key pauses the program or, in combination with CTRL, stops it from running.
Electronic Mouse
A mouse is a small device used to point to and select items on your computer screen. Although mice come in many shapes, the typical
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mouse does look a bit like an actual mouse. It’s small, oblong, and connected to the system unit by a long wire that resembles a tail.
Some newer mice are wireless. When you move the mouse with your hand, a pointer on your screen moves in the same direction. (The pointer’s appearance might change depending on where it’s positioned on your screen.) When you want to select an item, you point to the item and then click (press and release) the primary button. Pointing and clicking with your mouse is the main way to interact with your computer.
A mouse typically has two buttons: a primary button (usually the left button) and a secondary button (usually the right button). The primary button is the one you will use most often. Most mice also include a scroll wheel between the buttons to help you scroll through documents and webpages more easily. On some mice, the scroll wheel can be pressed to act as a third button. Advanced mice might have additional buttons that can perform other functions.
Figure 4d. Parts of a mouse
Holding and Moving the Mouse
Place your mouse beside your keyboard on a clean, smooth surface, such as a mouse pad. Hold the mouse gently with your index finger resting on the primary button and your thumb resting on the side. To move the mouse, slide it slowly in any direction. Don’t twist it; keep
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the front of the mouse aimed away from you. As you move the mouse, a pointer on your screen moves in the same direction. If you run out of room to move your mouse on your desk or mouse pad, just pick up the mouse and bring it back closer to you. Hold the mouse lightly, keeping your wrist straight. Figure 4d illustrate the explanation given.
Figure 4d. Mouse holding technique
Pointing, clicking, and dragging: Pointing to an item on the screen means moving your mouse so the pointer appears to be touching the item. When you point to something, a small box often appears that describes the item. For example, when you point to the Recycle Bin on the desktop, a box appears with this information: “Contains the files and folders that you have deleted.”
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Figure 4e.Pointing to an object to reveals a descriptive message about it
The pointer can change depending on what you’re pointing to. For example, when you point to a link in your web browser, the pointer changes from an arrow to a hand with a pointing finger . Most mouse actions combine pointing with pressing one of the mouse buttons. There are four basic ways to use your mouse buttons: clicking, double-clicking, right-clicking, and dragging.
Clicking (single-clicking): To click an item, point to the item on the screen, and then press and release the primary button (usually the left button). Clicking is most often used to select (mark) an item or open a menu. This is sometimes called single-clicking or left-clicking.
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Double-clicking: To double-click an item, point to the item on the screen, and then click twice quickly. If the two clicks are spaced too far apart, they might be interpreted as two individual clicks rather than as one double-click.
Double-clicking is most often used to open items on your desktop. For example, you can start a program or open a folder by double-clicking its icon on the desktop.
Right-clicking: To right-click an item, point to the item on the screen, and then press and release the secondary button (usually the right button). Right-clicking an item usually displays a list of things you can do with the item. For example, when you right-click the Recycle Bin on your desktop, Windows displays a menu allowing you to open it, empty it, delete it, or see its properties. If you’re ever unsure of what to do with something, right-click it. Right-clicking the Recycle Bin opens a menu of related commands
Figure 4f. Right clicking recycle bin
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Dragging: You can move items around your screen by dragging them. To drag an object, point to the object on the screen, press and hold the primary button, move the object to a new location, and then release the primary button. Dragging (sometimes called dragging and dropping) is most often used to move files and folders to a different location and to move windows and icons around on your screen.
Using the Scroll Wheel
If your mouse has a scroll wheel, you can use it to scroll through documents and webpages. To scroll down, roll the wheel backward (toward you). To scroll up, roll the wheel forward (away from you).
Customizing Your Mouse
You can change your mouse settings to suit your personal preferences. For example, you can change how fast your mouse pointer moves around the screen, or change the pointer’s appearance. If you’re left-handed, you can switch the primary button to be the right button.
Trackballs
A trackball is like a mouse turned upside down. It is a stationary device related to the mouse. It has a roller ball with only its top exposed outside its case. The cursor on the screen is moved whenever the roller ball is turned. Pressing buttons on the trackball activates various activities represented by the icon selected.
(a) A mouse
(b) A trackball
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Touch Screens
Touch screen is a special screen that is able to detect the position on the screen that a user‘s finger is touching or pointing at. A standard computer screen is covered by two very thin pieces of plastic. Embedded into the plastic is a fine wire and that is linked to the computer. When someone touches the grid, the computer can deduce exactly where the touch is made.
Joysticks
Joysticks are used more on video games than with PCs. A joystick has a short vertical handle that can be tilted forwards and backwards, left and right. A joystick allows the user to point to objects on the screen in the same way as a mouse, but it is more convenient for following a moving target. It may have one or more buttons on it.
Light Pen
A light pen allows the user to point the pen at different parts of a screen to select an option or draw a graphic, so it is like very accurate Touch screens. The use of light pens is quite rare.
Optical Scanners
Optical scanning devices read text or graphics and convert them into digital input for the computer. Thus, optical scanning enables the direct entry of data from source documents into a computer system. Optical scanners employ photoelectric devices to scan the characters being read. Reflected light patterns of the data are converted into electronic impulses that are then accepted as input into the computer system. Optical Character Recognition (OCR) is a form of optical scanning.
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Voice Recognition
Voice recognition systems analyse and classify speech or vocal tract patterns and convert them into digital codes for entry into a computer system. Voice recognition systems with large vocabularies require training the computer to recognise your voice in order to achieve a high degree of accuracy
Magnetic Stripe
Swipe and credit cards have black iron oxide coating of magnetic stripe on the reverse side, and it is this that the computer recognises. The black stripe holds information, such as customer account numbers, that can be accessed only by a special magnetic reading device. The reading device converts the information into computer usable form, for example, at the automated teller machines found at banks and at credit card authorization terminals.
Smart Cards
Smart Cards embed a microprocessor chip and several kilobytes of memory into debit, credit, and other cards. Smart debit cards enable the user to store a cash balance on the card and electronically transfer some of it to others to pay for small items and services. The balance on the card can be replenished in automated teller machines (ATMs) or other terminals. Smart cards are widely used to make payments in parking meters, vending machines, pay telephones, and retail stores.
Digital Cameras
Digital still cameras and digital video cameras (digital camcorders) enable the user to shoot, store, and download still photos or full motion video with audio into a PC. Then image-editing software can be used to edit and enhance the digitised images and include them in newsletters, reports, multimedia presentations, and web pages.
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Optical Character Readers
Optical character readers (OCR) are machines capable of reading printed documents directly into the computer by recognising the shape of the different characters. Reading of documents prepared in optical characters is accomplished by the use of a scanning device that reflects light from the character on to a lens where it is focused on a photoelectric cell. The cell produces a variable electric current that is unique for each character read. This process is termed optical character recognition.
Optical Mark Readers
Optical mark readers (OMR) are machines that use an artificial light source to scan marks made on OMR documents in order to determine their values. Marking is done in small horizontal shape on documents with black media such as a soft pencil. On OMR documents, predetermined positions are given certain values. The optical reader converts the mark in a position to the appropriate value. This is termed optical mark recognition (OMR).
Magnetic Ink Character Readers
Magnetic ink character readers (MICR) are machines capable of reading magnetic ink characters on MICR documents and passing the data into a computer. A MICR document has human-readable characters printed in the normal way with the use of a specially designed font but using a ferrous-based ink that is capable of magnetization.
Magnetic Ink Character Recognition (MICR) technology is employed by the computer systems of the banking industry to read cheques magnetically.
On-Line Input
This entails data being transmitted directly to the computer by the use of terminals sited at a distance from the computer and linked to
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it by communication arrangements. The computers‘ response is transmitted back to the terminal.
Bar Coding
Bar coding is the representation of code numbers or other data by bars or lines printed or embossed on a data carrier. The data carrier may be a tag, ticket, label, plastic card or a packet/can holding goods.
Universal Product Code
The Universal Product Code (UPC) system was introduced by the USA to cover the complete range of grocery products. Each product is given a unique 10-digit code that is represented in bar code form on every packet or other type of container or on labels. The bars are in pairs, each of which represents a digit according to their spacing and thickness. Certain symbols are also represented including those to indicate the start and finish of the bar coding. The European equivalent of UPC is the European Article Number (EAN).
Bar Code Readers
A bar code reader functions as follows: The bar code is scanned by a laser, which measures the thickness of the lines and the distance between them to decipher the code. Once read, the information can be transmitted to a computer. These hardware devices are often used for point-of-sale input systems in supermarkets and other outlets.
Output Devices
Computer output is the process of transferring data and information from the main storage of the computer onto a human-sensible medium or a machine-sensible medium. The principal methods of producing computer output are:
Displayed output on a VDU screen
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Printed output on paper
Computer-sensible output on a magnetic medium
Computer output on microform
Plotters
Sound output
Video Output
Video monitors use cathode ray tubes (CRT) technology similar to the picture tubes used in home TV sets. The clarity of the video display depends on the type of video monitor and the graphic circuit board installed in the computer. The information displayed on the screen is often referred to as soft copy. Monitors can be monochrome or colour. Monochrome monitors give a display of varying intensity on a single colour, for example, white on black background or orange/green on dark background. Colour monitors give a display with a range of colours determined by the colour circuitry in the monitor and the computer.
Printers/ Plotters
A printer is a mechanical device used for producing human-readable information on paper. A printer is connected to a computer for the sole purpose of transferring the information from the computer to paper or other media. The version printed out on paper is often referred to as hard copy. The three main categories of computer printers are line printers, serial/character printers and laser printers. A plotter contains a pen that draws lines on paper. Plotters are devices used for producing hard copies of complex graphics outputs in the form of graphs, charts, histograms and diagrams. These devices are much better than ordinary printers at handling diagrams. The technique has a wide range of use in fields such as scientific research, engineering and management information systems. They are commonly used for such tasks as producing technical drawings and road/rail networks.
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Magnetically Encoded Output
Computer output, in coded form, are written onto a magnetic medium usually for the purpose of storing updated records. The magnetic media used for the purpose include diskette, compact disk, magnetic tape, and magnetic disks.
Sound Output
A sound output device reproduces previously recorded and stored sounds. Sound output devices are the output equivalent of sound input devices. Sound output devices simply convey pre-recorded information in audio form. Speech synthesis is the production of sounds resembling human speech by electronic methods. A speech synthesis output device creates speech output from text. Speech synthesis output devices are the flipside of automatic speech recognition input devices. Speech synthesis devices convey information in audio form.
Backing Storage
Backing storage is an extension to a computer‘s internal storage. It is used for the off-line mass storage of programs, data and files that are not currently being used for processing. The types of common backing storage in use are magnetic tape, magnetic disk, compact disk, USB flash drive and floppy disk.
Magnetic Tapes
The magnetic tape consists of a strip of plastic tape coated with a magnetic material deposited in grains, each of which may be magnetized in one of two directions. A tape is held on a reel. A tape drive is used for writing data onto magnetic tape from the processor and for reading data from magnetic tape into the processor. The reading/writing operations are accomplished by a pair of read/write heads.
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Advantages of Magnetic Tape
It is relatively inexpensive, compared to the magnetic disk.
It has a large data storage capacity.
It is capable of transferring data to and from the main storage of the computer at very high speed.
Transaction data can be recorded directly onto the magnetic tape by means of magnetic tape encoding machines.
Old data may be erased and the tape used repeatedly.
Disadvantages Of Magnetic Tape
It is only possible to access records serially.
Data can be accidentally erased or overwritten.
It is not possible to read the records on tape visually.
Updated information cannot be written back to the same location on the same tape.
Input data must be sorted into the sequence of the master file before updating can start.
Stringent environment control is necessary in order to eliminate dust and static electricity in the atmosphere.
Magnetic Disks
A magnetic disk or hard disk is a flat circular device, which is similar to a long-playing phonograph record. It is made of metal and each of the recording surfaces is coated with a thin layer of magnetisable iron oxide. Usually, six disks are held on a common axis, one above the other, to form a disk pack. A disk pack is mounted on a disk drive mechanism. The disk drive is used for writing data onto magnetic disk from the processor and reading data from magnetic disk into the processor. The reading/writing operations are accomplished by using a pair of read/write heads placed next to each recording surface.
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Advantages of Magnetic Disk
A pack of disks has very high storage capacity.
Data on tracks may be overwritten with new data.
Disks are ideal for storing subroutines, tables and rates.
Disks may be used for real-time remote enquiry systems.
The speed of data transfer from the processor and to the processor is very high.
Data can be input onto a disk without the need for sorting.
Any item of data can be directly addressed, depending upon the method of the file organisation used.
Disadvantages of Magnetic Disk
Disk storage devices are more expensive than many other storage media.
Data may be accidentally erased or overwritten.
It is more complex to program disk operations than for magnetic tape.
Disk operations involve the locating of overflow records.
USB Flash Drive
A USB flash drive is a data storage device that includes flash memory with an integrated Universal Serial Bus (USB) interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disc. Most weigh less than 30 grams (1.1 oz). As of January 2013, drives of up to 512 gigabytes (GB) were available. A one-terabyte (TB) drive was unveiled at the 2013 Consumer Electronics Show and became available later that year. USB flash drives are often used for the same purposes for which floppy disks or CDs were used, i.e., for storage, back-up and transfer of computer files.
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Advantages of USB Flash Drive
They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts
Nothing epitomizes modern life better than the computer. For better or worse, computers have infiltrated every aspect of our society. Today computers do much more than simply compute: supermarket scanners calculate our grocery bill while keeping store inventory; computerized telephone
switching centers play traffic cop to millions of calls and keep lines of communication untangled; and automatic teller machines (ATM) let us conduct banking transactions from virtually anywhere in the world. But where did all this technology come from and where is it heading to? To fully understand and appreciate the impact computers have on our lives and promises they hold for the future, it is important to understand their evolution. Some of the events that lead to the evolution of computer are described as follows.
Early Computing Machines and Inventors
The abacus was emerged about 5,000 years ago in Asia Minor and is still in use today, may be considered the first computer. This device allows users to make computations using a system of sliding beads arranged on a rack. Early merchants used the abacus to keep trading transactions. But as the use of paper and pencil spread, particularly in Europe, the abacus lost its importance. It took nearly 12 centuries, however, for the next significant advance in computing devices to emerge. In 1642, Blaise Pascal (1623-1662), the 18-year-
old son of a French tax collector, invented what he called a numerical wheel calculator to help his father with his duties. This brass rectangular box, also called a Pascaline, used eight movable dials to add sums up to eight figures long. Pascal’s device used a base of ten to accomplish this. For example, as one dial moved ten notches, or one complete revolution, it moved the next dial – which represented the ten’s column – one place. When the ten’s dial moved one revolution, the dial representing the hundred’s place moved one notch and so on. The drawback to the Pascaline, of course, was its limitation to addition.
Figure 3a. Abacus Device
Figure 3b. Pascaline
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In 1694, a German mathematician and philosopher, Gottfried Wilhem von Leibniz (1646-1716), improved the Pascaline by creating a machine that could also multiply. Like its predecessor, Leibniz’s mechanical multiplier worked by a system of gears and dials. Partly by studying Pascal’s original notes and drawings, Leibniz was able to refine his machine. The centerpiece of the machine was its stepped-drum gear design, which offered an elongated version of the simple flat gear. It wasn’t until 1820, however, that mechanical calculators gained widespread use. Charles Xavier Thomas de Colmar, a Frenchman, invented a machine that could perform the four basic arithmetic functions. Colmar’s mechanical calculator, the arithometer, presented a more practical approach to computing because it could add, subtract, multiply and divide. With its enhanced versatility, the arithometer was widely used up until the First World War. Although later inventors refined Colmar’s calculator, together with fellow inventors Pascal and Leibniz, he helped define the age of mechanical computation.
Figure 3c. Leibniz Machine
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The real beginnings of computers as we know them today, however, lay with an English mathematics professor, Charles Babbage (1791- 1871). Frustrated at the many errors he found while examining calculations for the Royal Astronomical Society, Babbage declared, “I wish to God these calculations had been performed by steam!” With those words, the automation of computers had begun. By 1812, Babbage noticed a natural harmony between machines and mathematics: machines were best at performing tasks repeatedly without mistake; while mathematics, particularly the production of mathematics tables, often required the simple repetition of steps. The problem centered on applying the ability of machines to the needs of mathematics. Babbage’s first attempt at solving this problem was in 1822 when he proposed a machine to perform differential equations, called a Difference Engine. Powered by steam and large as a locomotive, the machine would have a stored program and could perform calculations and print the results automatically. After working on the Difference Engine for 10 years, Babbage was suddenly inspired to begin work on the first general-purpose computer, which he called the Analytical Engine. Babbage’s assistant, Augusta Ada King, Countess of Lovelace (1815-1842) and daughter of English poet Lord Byron, was instrumental in the machine’s design. One of the few people who understood the Engine’s design as well as Babbage, she helped revise plans, secure funding from the British government, and communicate the specifics of the Analytical Engine to the public. Also, Lady Lovelace’s fine understanding of the machine allowed her to create the instruction routines to be fed into the computer, making her the first female computer programmer. In the 1980’s, the U.S. Defense Department named a programming language ADA in her honor.
Figure 3d. Babbage Machine
Babbage’s steam-powered Engine, although ultimately never constructed, may seem primitive by today’s standards. However, it outlined the basic elements of a modern general purpose computer and was a breakthrough concept. Consisting of over 50,000 components, the basic design of the Analytical Engine included input devices in the form of perforated cards containing operating instructions and a “store” for memory of 1,000 numbers of up to 50 decimal digits long. It also contained a “mill” with a control unit that allowed processing instructions in any sequence, and output devices to produce printed results. Babbage borrowed the idea of punch cards to encode the machine’s instructions from the Jacquard loom. The loom, produced in 1820 and named after its inventor, Joseph- Marie Jacquard, used punched boards that controlled the patterns to be woven.
Figure 3e. Hollerith Machine
In 1889, an American inventor, Herman Hollerith (1860-1929), also applied the Jacquard loom concept to computing. His first task was to find a faster way to compute the U.S. census. The previous census in 1880 had taken nearly seven years to count and with an expanding population, the bureau feared it would take 10 years to count the latest census. Unlike Babbage’s idea of using perforated cards to instruct the machine, Hollerith’s method used cards to store data information which he fed into a machine that compiled the results mechanically. Each punch on a card represented one number, and combinations of two punches represented one letter. As many as 80 variables could be stored on a single card. Instead of ten years, census takers compiled their results in just six weeks with Hollerith’s machine. In addition to their speed, the punch cards served as a storage method for data and they helped reduce computational errors. Hollerith brought his punch card reader into the business world, founding Tabulating Machine Company in 1896, later to become International Business Machines (IBM) in 1924 after a series of mergers. Other companies such as Remington Rand and Burroghs also manufactured punch readers for business use. Both
Businesses and the government used punch cards for data processing until the 1960’s.
In the ensuing years, several engineers made other significant advances. Vannevar Bush (1890-1974) developed a calculator for solving differential equations in 1931. The machine could solve complex differential equations that had long left scientists and mathematicians baffled. The machine was cumbersome because hundreds of gears and shafts were required to represent numbers and their various relationships to each other. To eliminate this bulkiness, John V. Atanasoff (1903), a professor at Iowa State College (now called Iowa State University) and his graduate student, Clifford Berry, envisioned an all-electronic computer that applied Boolean algebra to computer circuitry. This approach was based on the mid- 19th century work of George Boole (1815-1864) who clarified the binary system of algebra, which stated that any mathematical equations could be stated simply as either true or false. By extending this concept to electronic circuits in the form of on or off, Atanasoff and Berry had developed the first all-electronic computer by 1940. Their project, however, lost its funding and their work was overshadowed by similar developments by other scientists.
3.2 Personal Computers History and Development
The personal computer (PC) has revolutionized business and personal activities and even the way people talk and think; however, its development has been less of a revolution than an evolution and convergence of three critical elements – thought, hardware, and software. Although the PC traces its lineage to the mainframe and minicomputers of the 1950s and 1960s, the conventional thought that was prevalent during the first thirty years of the computer age saw no value in a small computer that could be used by individuals. A PC is a microcomputer, so named because it is smaller than a minicomputer, which in turn is smaller than a mainframe computer. While early mainframes and their peripheral devices often took
the floor space of a house, minicomputers are about the size of a refrigerator and stove. The microcomputer, whose modern development traces back to the early 1970s, and fits on a desk, from the start, the creation of the computer was centered on the concept that a single unit would be used to perform complex calculations with greater speed and accuracy than humans could achieve. On December 23, 1947, one of the most far-reaching technologies of the 20th Century was developed at Bell Laboratories by John Bardeen, Walter Brattain, and William Shockley – the transistor. But the transistor wasn’t available to U.S. manufacturers until 1956, when a seven year-old antitrust law suit against AT&T, the owners of Bell Labs, was settled. The judgment required that AT&T give away licenses to manufacture the transistor to American companies. Following this decision, the transistor was used to replace thousands of vacuum tubes in computers and began the miniaturization of electronics. Because it drastically reduced the size and heat considerations of the large vacuum tubes, the transistor enabled the computer to become a viable tool for business and government.
3.3 The Computer Mystique
From the beginning, computers baffled the populous with their capability. In corporate and government offices and on university campuses, information processing departments sprouted up to serve the computer. The IBM 701, which was introduced in 1952 as a business computer, was comprised of several units that could be shipped and connected at a customer’s location, rather than the earlier massive units that had to be assembled on site. In 1953, IBM began shipping the first mass-produced computer, the IBM 650. IBM introduced the first solid-state (transistorized) computer in 1959, the IBM 7090. Then in 1964, IBM culminated over $1 billion in research when it brought out the System/360 series of computers. Unlike other mainframes, the System/360 computers were compatible with each other.
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By 1960, the computer was king. Companies hired armies of technicians and programmers to write its operating programs and software, fix it, and allocate the precious computer time. The capability of the machines was more than a mere mortal could fathom, but gathering raw data and “keying” it in so the computer could “crunch the numbers” was a complicated and time-consuming task.
Frustrations abounded, computer errors were called “glitches,” and the phrases “garbage in/garbage out,” “It’s a computer mistake,” and “Sorry, the computer’s down and we can’t do anything,” were introduced into the lexicon.
On college campuses in the 1960s, students carried bundles of computer cards to and from class, hoping that their share of the valuable computer time would not be bumped or allocated to someone else. The term, “Do not fold, spindle or mutilate,” was coined so people wouldn’t disable the process of feeding the punched computer cards into punch card readers, where the intricate patterns of holes were decoded.
The computer mystique was reinforced in people every time they heard of some new accomplishment. In 1961, a computer calculated the value of pi to 100,000 decimal places. A computer could play checkers, and in 1967 a chess playing computer program was made an honorary member of the United States Chess Federation. Banks began printing checks with magnetic ink so they could be processed by the computers.
3.4 New Technologies And Ideas
Until 1971, nobody even thought of a computer as anything but a big, fast, electronic brain that resided in a climate-controlled room and consumed data and electricity in massive quantities. In 1971, an Intel 4004 chip containing 4004 transistors was programmed to perform complex mathematical calculations; the hand-held calculator was born. Suddenly, scientists and engineers could carry
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the computational power of a computer with them to job sites, classrooms, and laboratories; but the hand-held calculator, like the ENIAC before it, was not yet a computer. The microprocessor was developed by Robert Noyce, the founder of Intel and one of the inventors of the integrated circuit, and brought with it a change in the way people worked.
Small, hand-held calculators had provided an idea, or at least a “what if,” to some people. Still, in the early 1970s, computers were used for number crunching and printing out long streams of green and white paper. IBM electric typewriters were the top of the line “word processors” and Xerox copiers churned out photocopies. Most people never imagined that a computer could process data in real time, be used to write letters, or fit on a desk.
In 1972, Intel brought out its 8008 chip, capable of processing 8-bits of data, enough to convey numbers and letters of the alphabet. In that same year, Xerox began working on a personal computer at their Palo Alto Research Center. For the next several years, a team of Xerox scientists worked on the “Alto,” a small computer that would have become the first PC if only the development team had been able to convince someone of its usefulness.
Likewise, in 1972 Digital Equipment Corporation (DEC), a minicomputer manufacturing company headed by Kenneth Olsen, had a group of product engineers developing the DEC Datacenter. This PC incorporated not only the computer hardware but the desk as well. The DEC Datacenter could have put tremendous computing capability in the home or at work, but management saw no value to the product and halted its development.
In the end, none of the giant companies whose names had been synonymous with computers would introduce the PC to the world. There seemed to be no future in an inexpensive product that would replace the million dollar “Big Iron” that they were selling as fast as they could make them.
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The people who eventually introduced the PC were rebels. Many had spent time in the bowels of the big companies and were frustrated by the lack of vision they encountered. They retreated into their own garages and attended meetings with other “computer nuts” who saw a much different future than the one laid out over the previous 30 years by the giants of the computer industry.
3.5 The Birth Of Personal Computer
In 1975, Rubik’s Cube was put on store shelves and proved to many that the human brain was incapable of complex problem solving. But a ray of hope also appeared; the first PC was introduced. Micro Instrumentation and Telemetry Systems, Inc. (MITS) sold a kit for the MITS Altair 8800 that enabled computer hobbyists to assemble their own computers. It had no monitor, no keyboard, no printer, and couldn’t store data, but the demand for it, like Rubik’s Cube, was overwhelming.
The Altair proved that a PC was both possible and popular, but only with those people who would spend hours in their basements with soldering irons and wire strippers. The Altair, which looked like a control panel for a sprinkler system, didn’t last, but it helped launch one of the largest companies in the computer world and gave a couple of young software programmers a start. In 1974, Bill Gates and Paul Allen wrote a version of BASIC for the Altair and started a company called Microsoft Corporation.
In 1976, another computer kit was sold to hobbyists – the Apple I. Stephen Wozniak sold his Volkswagen and Steve Jobs sold his programmable calculator to get enough money to start Apple. In 1977, they introduced the Apple II, a pre-assembled PC with a color monitor, sound, and graphics. It was popular, but everyone knew that a serious computer didn’t need any of this. The kits were just a hobby and the Apple II was seen as a toy. Even the Apple name wasn’t a serious, corporate sounding name like IBM, Digital Equipment Corporation, or Control Data.
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But 1977 also brought competition. The Zilog Z-80 microprocessor, which had been introduced in 1975, was used in the Tandy Radio Shack TRS-80, affectionately called the “Trash 80.” Apple, Commodore, and Tandy dominated the PC marketplace. The Apple II had 16K bytes of RAM and 16K bytes of ROM; Commodore Business Machines’ Personal Electronic Transactor (PET) included 4K RAM and 14K ROM; and the TRS-80 had 4K RAM and 4K ROM.
Also in 1977, the Central Program for Microprocessors (CP/M) operating system was developed by Digital Research and Gary Kildall. From its introduction until 1980, CP/M was used in most PCs, but even that did not guarantee that a program or document could be written on one machine and read on another because each manufacturer used different floppy disk drives.
Apple introduced the floppy disk drive in 1978, allowing Apple II users to store data on something other than the cumbersome and unreliable tape cassettes that had been used up to that point. But despite the popularity of the three PCs, non-computer people still saw little reason to buy an expensive calculator when there were other ways to do the same things. In 1979, that all changed.
When VisiCalc was introduced for the Apple II, non-computer people suddenly saw a reason to buy a computer. VisiCalc, a spreadsheet program created by Dan Bricklin and Bob Frankston, allowed people to change one number in a budget and watch the effect it had on the entire budget. It was something new and valuable that could only be done with a computer. For thousands of people, the toy, the computer few could find a use for, had been transformed into a device that could actually do something worthwhile.
Microprocessors and high-tech gadgets were gradually worming their way into people’s lives. In 1978, Sony introduced the Beta format video cassette recorder and a year later the VHS video recorder and the Sony Walkman. And to remind everyone of how
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far we had to go, Star Trek: The Motion Picture came to theaters in 1979.
The Sinclair ZX-80 PC, which hit the market in 1980, used the same Z-80 chip as Commodore’s PET and the Tandy TRS-80. The ZX-80 had 1K RAM and 4K ROM. Developed by British entrepreneur Clive Sinclair, the ZX-80 meant that people could enter the computer revolution for under $200. Its small size and price attracted people who had never thought about owning a PC.
The Commodore VIC-20, also introduced in 1980, had a color monitor and would eventually become the first PC to sell more than one million units. Even with all of the success the early PC manufacturers had in the late 1970s and early 1980s, the advances in microprocessor speeds, and the creation of software, the PC was still not seen as a serious business tool. Unknown to everyone in the computer industry; however, a huge oak tree was about to drop an acorn that would fall close to the tree and change everything.
Two events occurred in 1981 that would have a tremendous impact on the future of the PC. In 1980, IBM had started a secret project in Boca Raton, Florida called “Acorn.” Thirteen months later, in 1981, IBM introduced the IBM PC, a product that validated the PC as a legitimate business tool. For many people, even those who prided themselves on being able to operate the “Big Iron,” if IBM was making PCs then the small desk-top units were worthy of respect.
When the IBM PC hit the market, it was a complete system. Secretly, IBM had provided software developers with prototypes of their PC so they could develop an array of programs that would be available when the machine hit the streets. IBM also developed printers, monitors, and expansion cards for the PC and made it an open system so other manufacturers could develop peripherals for it. The IBM PC used an Intel 8088 microprocessor, had 16K of RAM, was expandable to 256K, came with one 5.25-inch disk drive and room for a second, and was available with a choice of operating
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systems; CP/M-86 or IBM PC-DOS, which had been developed by Microsoft.
The second major event of 1981 was the introduction of the first luggable computer, the Osborne 1. This self-contained, suitcase- sized PC, developed by Adam Osborne, was not only the first portable PC, but also the first to be sold with software. The Osborne I came with BASIC, CBASIC, WordStar for word processing, and the SuperCalc spreadsheet program. Over the next two years, the Osborne Computing Company would go from nothing to a company with $70 million in annual revenue and then into bankruptcy.
Prior to 1980, the most common method of storing data was to connect an audio tape recorder to the PC and dump data to standard tape cassettes. Large word processors and some PCs had 8-inch disk drives, but in 1980 Al Shugart introduced the Winchester hard-disk drive. The microprocessor, an amazing technology when it had 4000 transistors on a single chip, is now even more amazing when it has over 3 billion transistors on an even smaller chip. In 1982, when Time magazine made the computer its “Man of the Year,” the PC was still in its infancy. “Big Iron” still dominated the high-tech environment and having a personal computer was a luxury.
The creation and success of the PC would not have been possible without the elimination of the concept that a computer was a large, centralized, data processor and number cruncher. Today the PC is a communication channel more than it is a computational tool. Millions of people work in their “electronic cottages,” either operating their own business from home or telecommuting to work. It is strange that one of the first Intel 4004 microprocessors ever made continues to operate and lead the world to the outer edges of time and space. In 1972 one of the small chips was installed in the Pioneer spacecraft. Today it continues to operate over 5 billion miles from earth.
3.6 Industrial Contribution To Evolution Of Computer
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The early 1980s were a time of furious change in the computer industry. More than 100 companies were manufacturing PCs, each with its own unique features, each with its own software. When IBM entered the market in 1981, software companies knew that writing IBM compatible software would be profitable. Software for the Apple II had exploded to 16,000 titles and IBM would do the same. New software in the 1980s included WordStar, Lotus 1-2-3, Microsoft Word, and Word Perfect.
In 1981, Hayes Micromodem brought the MOdulator/DEModulator (MODEM) to the market for PCs. The modem had been invented at AT&T Bell Labs in 1960 to connect mainframes and minicomputers. Hayes’ modem allowed PCs to communicate with each other and access CompuServe and The Source, the online services that started up in 1979. CompuServe showed people what to do with their 300 baud modems by offering them an array of services and databases to connect with.
In 1982 Compaq introduced the first IBM compatible machine. Until Compaq, most manufacturers feared IBM and would not bring out a machine that was compatible with the PC. Later the compatibles would be termed “clones.”
Also in 1982, Tandy brought out the TRS-80 Model 16, which was based on the Motorola 68000 and Z-80 microprocessors. The Model 16 retailed for $5,000 and included 128K RAM, an 8-inch floppy disk drive, as well as the Xenix operating system, a derivative of UNIX.
In January, 1983 Time magazine anointed the PC as the “Man of the Year,” a designation by the editors that the computer had been the most influential newsmaker of 1982. The magazine estimated 80 million PCs would be in use by the end of the century. Industry leaders included Texas Instruments, Timex, Commodore, Atari, Apple, IBM, and Tandy, with Osborne leading the way in the portable market. The individuals pushing the PC into the future were John Opel at IBM, Adam Osborne of Osborne Computers, VisiCalc
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creator Dan Bricklin, Jack Tramiel of Commodore, and Clive Sinclair who founded Sinclair Research.
The leading products of 1982 and their sales figures included the Timex/Sinclair 1000 – 600,000; Commodore VIC-20 – over 600,000, Atari 400 and Atari 800 – 600,000; Texas Instruments 99/4A – 530,000; TRS-80 Model III – 300,000; Apple II Plus – 270,000; IBM
PC – 200,000; and Osborne 1 – 55,000. These computers ranged in price from the $99 Timex/Sinclair to the Osborne 1 at $1,795 with bundled software. In the opinion of Time, computers priced over
$2,000 would appeal to a market of “…growing small businesses and big corporate clients…” Manufacturers of these higher end PCs included Altos, Corvus, Cromemco, Control Data, Digital Equipment, Hewlett-Packard, North Star, Olivetti, Tele Video, Toshiba, Xerox, and Zenith.
In 1983, there was once again a wind of change blowing across the PC landscape. Apple brought out a machine that failed to sell but nonetheless showed consumers and manufacturers a new direction for the PC. The Lisa, an expensive PC with a graphical user interface (GUI), hit the market with a thud. At $10,000, it had few friends and even fewer buyers. Also in 1983, IBM introduced IBM XT with a 10MB hard drive, three additional expansion slots, 128K RAM, and a 360K floppy drives. To many buyers, the 10MB storage capacity seemed large enough to last a lifetime.
Immediately after the failure of Lisa, Steven Jobs rethought the machine and in 1984, out came the Macintosh. The Macintosh was powered by Motorola’s 68000 processor and came with 128K of RAM. It was so radically different from any other PC that it split the PC world into two halves that would not be rejoined for another decade. In addition to the GUI that made the computer an “intuitive” extension of the user, the “Mac” had its own operating system that was incompatible with IBM’s MS-DOS system. Suddenly PC meant DOS-based and IBM compatible and Mac meant GUI and mouse.
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The Mac was introduced to the world in an extravagant television commercial that was shown only once during half-time of the NFL Super Bowl. The commercial changed the advertising industry almost as much as the Mac changed computing. Suffering from the failure of the Apple III and Lisa, Apple was literally saved by the Mac. People who hated computers loved the simplicity of Mac. The GUI allowed the user to click a mouse button on an icon to launch a program, print a document, or copy a file. No longer did users have to know combinations of keys or special codes to get the computer to do what they wanted it to do. The Mac was “user friendly.”
When Apple came out with the Apple LaserWriter in 1985 it was with Adobe Systems Inc.’s PostScript page description language. By 1986, with its what-you-see-is-what-you-get (WYSIWYG) display and printing, desk-top publishing was born. WYSIWYG meant that a person could format a document with special fonts and spacing and be assured that what came out of the printer would look like what they had created on the screen.
Adobe, founded in 1982 by John Warnock and Charles Geschke, turned the printed page into a graphic image. The bit map made each pixel on the screen a definable image that could be moved and changed without the limitations of a standard text format. PostScript changed the way people thought about fonts, page layout, and the visual impact of the documents they produced with their PC. Printers like the Apple LaserWriter and the Hewlett-Packard HP LaserJet made every document look like it had been professionally typeset and printed.
In 1985, the Commodore Amiga 1000, which featured multitasking, graphics, sound, and video in a windowing operating system, exposed people to multimedia. At the same time Toshiba came out with the T1100 laptop, Tandy introduced the Tandy 200 laptop, and AT&T introduced the UNIX PC. Intel took the microprocessor to a new level when it brought out the 386 microprocessor in 1985,
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proving that PCs were not only getting better, but they were also getting faster.
The 1980s were very active times for hardware manufacturers and software producers. Small software companies locked in with either IBM or Macintosh, but large companies like Microsoft were able to create new applications for both operating systems. While Aldus brought out PageMaker, and Lotus introduced Jazz, Microsoft announced Excel for the Mac, C 3.0, and finally shipped a long-awaited program called Windows.
Bill Gates, a founder of Microsoft, tried three times to interest IBM in Windows but was turned down each time. Although the Mac operating system had changed the interface between users and their PCs, many DOS users continued to hang on to their command line- driven MS-DOS operating system, and it would be several more years until the Windows concept caught on.
With the availability of hundreds of software programs, hard disk space became valuable real estate. The 10MB hard disk on the IBM XT began to fill up so hard drive manufacturers started the process of doubling their capacity.
As modems proliferated and the Hayes Smart modem was accepted as the standard for modems, just about everyone either knew someone they could get online with, subscribed to an online service such as CompuServe, or wanted to access the 1000 host sites on the Internet. But PCs that were connected to the outside world were also vulnerable to a new phenomenon called viruses. Once downloaded, these programs could attach themselves without warning to a PC’s hard drive and gradually or in the blink of an eye destroy or overwrite files. Virus checkers then became the rage for anyone who received data over telephone lines.
By 1987 enough people were writing their own software and sharing it that the Association of Shareware Professionals was formed to market and protect the inexpensive software. In 1987 a new
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computer language, C++, stimulated the growth of object-oriented programming (OOP).
In 1990, Intel’s 386 and Motorola’s 68030 microprocessors were at the top, then in 1991 Intel brought out the i486SX 20 MHz chip and Motorola introduced the 68040. Less than a year later Intel introduced the 50MHz 486 chip and Tandy brought out its $400 CD- ROM drive for PCs. Then, just to make everyone wonder what was going on, in 1991 Apple and IBM agreed to share technology by integrating the Mac into IBM’s systems and using the IBM Power PC chip.
In 1992, Apple brought out the Apple PowerBook, a laptop that made everyone wonder just how small a full-function computer could get. A year later everyone knew the answer when Apple introduced the Newton Personal Digital Assistant (PDA). The Newton was supposed to be able to recognize hand-written notes and Apple sold 50,000 of them in 10 weeks.
In 1993, Intel introduced the 60MHz Pentium chip, the next generation of chips. The Pentium; however, had a nasty mathematical bug and its acceptance was slowed. Apple discontinued the workhorse of its fleet, the Apple II, which, despite the mind boggling changes in the industry, had lasted 17 years. From its inception in 1975, the PC has become a focal point of business, education, and
omputer is a device that is capable of automatically accepting (i.e. input), storing and processing data into useful information (i.e. output), at a very high speed, under the control of stored instructions (i.e. program). A computer could also be defined as a machine for manipulating data according to a list of instructions (programs). The computer is the backbone of ICT.
2.2 Parts of a Computer
If you use a desktop computer, you might already know that there isn’t any single part called the “computer.” A computer is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware. (Software, on the other hand, refers to the instructions, or programs, that tell the hardware what to do.)
The illustration below shows the most common hardware in a desktop computer system. Your system may look a little different, but it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.
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2.2.1 System Unit
The system unit is the core of a computer system. Usually it’s a rectangular box placed on or underneath your desk. Inside this box are many electronic components that process information. The most important of these components is the central processing unit (CPU), or microprocessor, which acts as the “brain” of your computer. Another component is random access memory (RAM), which temporarily stores information that the CPU uses while the computer is on.
The information stored in RAM is erased when the computer is turned off. Almost every other part of your computer connects to the system unit using cables. The cables plug into specific ports (openings), typically on the back of the system unit. Hardware that is not part of the system unit is sometimes called a peripheral device or device.
2.2.2 Storage
The computer has one or more disk drives—devices that store information on a metal or plastic disk. The disk preserves the information even when your computer is turned off.
2.2.3 Hard disk drive
Computer’s hard disk drive stores information on a hard disk, a rigid platter or stack of platters with a magnetic surface. Because hard disks can hold massive amounts of information, they usually serve as your computer’s primary means of storage, holding almost all of your programs and files. The hard disk drive is normally located inside the system unit.
Figure 2b. Hard disk drive
2.2.4 CD and DVD Drives
Computers today come equipped with a CD or DVD drive, usually located on the front of the system unit. CD drives use lasers to read (retrieve) data from a CD, and many CD drives can also write Page 19 of 288 Information Communication Technology (ICT)
(record) data onto CDs. If you have a recordable disk drive, you can store copies of your files on blank CDs. You can also use a CD drive to play music CDs on your computer.
Figure 2c. CD
DVD drives can do everything that CD drives can, plus read DVDs. If you have a DVD drive, you can watch movies on your computer. Many DVD drives can record data onto blank DVDs.
2.2.5 Floppy disk drive
Floppy disk drives store information on floppy disks, also called floppies or diskettes. Compared to CDs and DVDs, floppy disks can store only a small amount of data. They also retrieve information more slowly and are more prone to damage. For these reasons, floppy disk drives are less popular than they used to be, although some computers still include them. Why are floppy disks “floppy”? Even though the outside is made of hard plastic, that’s just the sleeve. The disk inside is made of a thin, flexible vinyl material
Figure 2d. Floppy disk
.
2.2.6 Mouse
A mouse is a small device used to point to and select items on your computer screen. Although mice come in many shapes, the typical mouse does look a bit like an actual mouse. It’s small, oblong, and connected to the system unit by a long wire that resembles a tail. Some newer mice are wireless. A mouse usually has two buttons: a primary button (usually the left button) and a secondary button. Many mice also have a wheel between the two buttons, which allows you to scroll smoothly through screens of information.
Figure 2e. Mouse
When you move the mouse with your hand, a pointer on your screen moves in the same direction. (The pointer’s appearance might change depending on where it’s positioned on your screen.) Page 21 of 288 Information Communication Technology (ICT)
When you want to select an item, you point to the item and then click (press and release) the primary button. Pointing and clicking with your mouse is the main way to interact with your computer.
2.2.7 Keyboard
A keyboard is used mainly for typing text into your computer. Like the keyboard on a typewriter, it has keys for letters and numbers, but it also has special keys:
The function keys, found on the top row, perform different functions depending on where they are used.
The numeric keypad, located on the right side of most keyboards, allows you to enter numbers quickly.
The navigation keys, such as the arrow keys, allow you to move your position within a document or webpage.
Figure 2f. Keyboard
Note: We can also use your keyboard to perform many of the same tasks you can perform with a mouse.
2.2.8 Monitor
A monitor displays information in visual form, using text and graphics. The portion of the monitor that displays the information is called the screen. Like a television screen, a computer screen can show still or moving pictures.
There are two basic types of monitors: CRT (cathode ray tube) monitors and LCD (liquid crystal display) monitors. Both types produce sharp images, but LCD monitors have the advantage of being much thinner and lighter. CRT monitors, however, are generally more affordable.
A printer transfers data from a computer onto paper. You don’t need a printer to use your computer, but having one allows you to print e-mail, cards, invitations, announcements, and other materials. Many people also like being able to print their own photos at home. The two main types of printers are inkjet printers and laser printers. Inkjet printers are the most popular printers for the home. They can print in black and white or in full color and can produce high-quality photographs when used with special paper. Laser printers are faster and generally better able to handle heavy use.
Speakers are used to play sound. They may be built into the system unit or connected with cables. Speakers allow you to listen to music and hear sound effects from your computer.
Figure 2i. Computer Speakers
2.2.9. Modem
To connect our computer to the Internet, we need a modem. A modem is a device that sends and receives computer information over a telephone line or high-speed cable. Modems are sometimes
built into the system unit, but higher-speed modems are usually separate components.
Figure 2j. Cable Modem
2.3 Advantages of Computer System
Below are some advantages of computer systems
i. Accuracy and Reliability: The results produced by a computer are extremely correct and reliable. What is often called ‗computer errors‘ are actually human mistakes; invalid data and errors are corrected easily.
ii. Speed: The speed of computer makes it the machine ideal for processing large amounts of data; e.g. accounting, banking operations etc.
iii. Storage/Memory Capability: Computer systems can store tremendous amounts of data, which can then be retrieved fast
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and efficiently. The volume of information we deal with today is far beyond what we can handle manually.
iv. Productivity: Computers are able to perform dangerous, boring, routine jobs, such as adding long list of numbers, punching holes in metal or monitoring water levels. Most workers (e.g. in banks) will appreciate increased productivity when computers are used to do their jobs.
v. Flexibility: Computer could be used for various purposes
e.g. multiprogramming, batch processing, real-time processing, data collection, bank transaction processing etc.
vi. Automatic operation: Computer performs data processing automatically under the control of internally stored programs.
vii. Configuration and adaptability: Different or suitable peripherals may be used by business organizations to suit their business processing requirements.
2.4 Disadvantages of Computer System
Some of the dis-advantages of computers are discussed below
i. Cost of initial setup may be high.
ii. Cost of maintenance may be high.
iii. Inefficient feasibility study before implementation may hamper business operations.
iv. Lack of skilled personnel may hamper computer operations and results obtained.
v. Requires regular electrical power supply.
vi. Excessive exposure to computer may result in some health problem such as poor eye sight, wrist pain, back ache, neck pain etc.
vii. Computer virus attack may infect and destroy Data/information, which will automatically affect business operations.
viii. It may lead to unemployment, because one computer can do the job of about 10 persons.
2.5 Application of Computer in Society
Computers have moved into many facets of our lives. There is virtually no area of human endeavor that computer usage has not penetrated. Though we cannot exhaust listing all the areas of application of computers, the following are some key areas of computer application:
Science: One of the most important advantages of computers is in the field of science for research and development. The computers have played a major role in most of what we know about ourselves and the universe. The satellites, the telescopes and almost all the research tools make use of computers in some or the other way. The huge calculations required for space science, safe communication between scientists, storage of all the gathered information are some of the computer uses in science and technology.
Medical: The important use of computers in the medical field is for research and development. The high end machines used for diagnosis and cure of many diseases are nothing but computers. For example, the Magnetic Resonance Imaging (MRI), CT scan, ultrasound devices, etc are amongst the uses of computers in hospitals. Even many surgical procedures, known as laparoscopic surgeries, need the help of computers. Web conferencing helps doctors treat people remotely.
Education: Computer uses in the field of education are infinite. The Internet is a huge source of information. There are online universities that deliver online degrees and distance learning is spreading far and wide. Many schools and colleges have started making use of audio-visual ways of
imparting knowledge. A horde of tools that need a computer, help students in many ways.
Banking: The banking sector has improved on fronts such as security, ease of use, etc. with the help of computers. Most of the banking operations can be done online, known as Internet banking, and you don’t have to walk up to the bank for virtually anything. You can withdraw money from ATMs and deposit money in any branch, thanks to the networking affected by the use of computers. The complete banking experience has also become safer.
Crime Investigation: High end computer devices have ensured that justice is more effective. CCTV cameras and other computer operated security systems have reduced the amount of crime. And if it still happens there are many ways to track down the criminal in no time. Forensic science employs computers for many of its operations related to investigations.
Entertainment: The field of entertainment has been revolutionized by computers. Animation, graphic image manipulation etc has made the entertainment experience hundred times better. Computer gaming is achieving new landmarks in terms of technology. Movie making, editing, music composition etc everything needs computers. This is only the tip of the iceberg and the uses of computers in society are many more. But then the development of computer technology has also given rise to many vices like identity theft.
Government: The Government can use computers for the processing of immigration, tax collection/administration, keeping tracks of criminals, computing budgets and statutory allocations, Civil Service Records, computing wages, salaries, gratuities and pensions etc.
Communication: Any computer has any potential to link up with other computers through communication systems such as telephone lines or satellite. This link-up facilitates exchange of memos, reports, letters, data/information, and even having meetings among people in geographically dispersed locations.
Robotics: Robots are information machines with the manual dexterity to perform tasks too unpleasant, too dangerous, or too critical to assign to human beings. For example, robots are used in defense to perform underwater military missions; robots could be used for welding or paint-spraying in factories, and in car assembling.
Business/Commerce: Products are packaged with zebra- striped symbols (Universal Product Code {UPC}) that can be read by scanners at supermarket checkout stands to determine prices of commodities. It has become a commonplace for companies and consumers to transact business among themselves with the help of computers. It could be in form of Business-to-Business {B2B} or Business-to-Consumer {B2C}. Computers have been found useful in payroll preparation, inventory control, auditing operations, personnel records keeping, preparation of consumer utility bills, financial market transactions etc.
Energy: Energy companies use computers and geological data to locate oil, coal, natural gas and other mineral resources. Meter-readers use hand-held computers to record how much energy is used in a month in homes and businesses. Computers can analyze the fuel consumption in our cars.
2.6 Types of Computer System
Classifications of computer vary and also depend on some criterion as discussed below:
Criterion 1: Types by Data Processed
There are three (3) types of computers according to this classification criterion:
Analog Computers: An analog computer measures and operates on data that are represented in the form of continuous variables e.g. voltage, pressure, temperature, distance, speed etc. Examples of analog computers include car speedometer, multimeter, fuel pump at filling stations etc.
Digital Computers: A digital computer represents and processes data in discrete/numerical form, using binary system. It produces discrete output. Most computer systems we see around us today are digital computers; they are found in our homes and business environments. Some wrist watches today have digital computers embedded in them. Examples include desk calculators, adding machines, personal computers etc.
Hybrid Computers: A hybrid computer combines the features of both analog and digital computers. It can accept continuous, discrete or both type of input. Its output could be in the form of discrete or continuous values or the combination of both. This type of computer is commonly found in highly scientific environments. Example is the electronic calculating scale used in food stores.
Criterion 2: Computer Types by physical size
In classifying computer according to physical size, there are four (4) types, namely and computers in this category are digital in nature:
Microcomputers: Microcomputers are the smallest in size; they are the cheapest; and they have the least operational speed and memory capacity. They are made for single user and single-tasking. They are portable (i.e. they can be moved about easily), easy and simple to learn and use. The microprocessor of a microcomputer is made of integrated circuits, called chip, mounted a single circuit board. It has interfaces for input, output and storage devices. Examples include IBM Personal Computers and compatible systems, Compaq, Dell etc. Microcomputers come in different shapes and sizes: Personal Computer (PC) System: is a microcomputer designed for independent use by an individual at work or in the home mainly for business purposes. Some PCs are called Home Computers because they have limited capability designed for domestic use with programs that are typically used for computer games and controlling family finances.
Minicomputers: Minicomputers are medium-sized, general- purpose digital computers; a bit larger than microcomputers but smaller than mainframe computers. They are multi-user (i.e. supports many users at a time) and multi-tasking (i.e. ability to perform many tasks simultaneously). Compared with microcomputers, they have larger memory size, higher processing speed, more numerous and faster input/output devices; and they are costlier. They are used in small-scale industries. Examples of mini-computer include: PDP-8, PDP-11, Honeywell-DPS6, DEC‘s VAX series, Texas instrument DS990, IBM 8100 etc.
Mainframe computers: Mainframe computers are generally more powerful in terms of processing speed than minicomputers. They have larger memory storage memory/capacity and cost more than minicomputers. They are multi-user and multi-tasking oriented, supporting full range of programming languages, used for commercial and scientific research purposes, with sophisticated devices attached. They can access numerous terminals/workstations on a network. They use different types of peripheral devices such as tapes and disks. They are operated by well-trained
experts. Examples of mainframe computers include: NCR 8000, IBM 370,
Super computers: Supercomputers are the largest, fastest and most expensive computers. They are often referred to as Maxi-computers. They can be seen as technological improvement on mainframe computers. They are often used in scientific environments such as in space studies and weather forecast. Examples include: CRAY-1, CRAY-2
Criterion 3: Computer Types by Purpose
There are two types of computers according to classification by purpose:
General purpose computers: General purpose computers are designed to solve wide range of problems such as science, technology, education, business etc. Complex calculations are performed within fractions of a second and results obtained fast. Most Personal Computers (PCs) are general purpose computers.
Special purpose computers: Special purpose computers are designed for a particular job/purpose only; to solve problems of a restricted nature. They are also called dedicated computers. Most special purpose computers are put within some other devices or systems, such that the computers are not accessed directly. These types of computers are called Embedded Computers. Examples include computers designed for use in digital watches, micro-wave oven, in petrol pumps or in weapons guidance systems.
Criterion 4: Computer Types by generations/Technology Age There are five (5) generations of computers as at date based on this criterion.
First Generation Computers: These are computer systems manufactured during the 1940s. Their features include
The CPU was made of vacuum tubes or thermionic valves.
Primary memory made of magnetic drum.
The Visual Display Unit (VDU) or monitor used cathode ray tube.
Very bulky in size, occupied space, and very costly.
Used machine language programming.
Complex and cumbersome to operate.
Generated a lot of heat.
Examples are: EDSAC, EDVAC, LEO, UNIVAC I and UNIVAC II.
Second Generation Computers: These are computer systems manufactured during the 1950s. Their features include:
The CPU was made of electronic transistors.
Primary memory made of magnetic core.
Cost less, faster, smaller and more reliable than first generation systems.
Less complex and easier to operate compared with first generation.
Generated less heat than first generation.
Examples: LEO Mark III, ATLAS, Honeywell 800, UNIVAC III, IBM 7000 series, etc.
Third Generation Computers: These are computer systems manufactured around the 1960s and early 1970s.
Features:
The CPU was made of Small Scale Integrated (SSI) Circuits, built on one Silicon Chip.
The SSI circuits evolved to Medium Scale Integrated (MSI) circuits.
The MSI eventually evolved into Large Scale Integrated (LSI) circuits, leading to greater degrees of integration of electrical components.
The various evolutions of IC technologies gave rise to computer systems which were smaller in size, cheaper, faster, more reliable and durable than first and second generation systems.
It was the era of minicomputers and microcomputers, resulting in higher awareness of computer technology.
The VDU were in colours.
Primary memory made of magnetic core and solid state semi-conductors.
Less complex and easier to operate compared with first and second generations.
Used high level language e.g. COBOL for operation. Examples: ICL 1900 series, IBM 360 series etc.
Fourth Generation Computers: These are computer systems manufactured around the late 1970s to 1985. Features include the following:
The CPU was made of Very Large Scale Integrated Circuits (VLSIC), called microchips; i.e. thousands of components in a very small space.
There was a thin line demarcation between third and fourth generations.
The VLSI circuits gave rise to computer systems which were more compact, cheaper, faster, more reliable and durable than first, second and third generation systems.
It was the era of microcomputers, resulting in higher awareness of computer technology.
Invention of microprocessors, which gave birth to pocket calculators, digital watches and the inclusion of micro hips in other devices.
Use of fourth generation query language (4GLs).
The VDU were in various designs – RGB, EGA, CGA, VGA colour monitors.
Primary memory made of solid state semi-conductors.
Less complex and easier to operate compared with first and second generations.
Evolution of more application areas of computers.
v. Fifth Generation Computers
The research into the fifth generation computers started about 1985 and continued into 1990. The features are as follows:
This generation is characterized by the advent of Artificial intelligence, i.e. the ability of computer system to exhibit behaviors like an intelligent person.
Speech recognition/processing
Parallel architecture/processing – where a computer system have hundreds of processors that could all be working on different parts of a single complex problem simultaneously.
Pattern recognition –
Expert system – an application program that has the capability of making judgments and decisions like a human expert in a particular field of profession. It is an interactive system that puts users through question-and-answer session to clarify issues and make recommendations, e.g. in medicine.
Multimedia system – PC + Sound Card + Speakers + CD Drive
Semi-conductor memory.
2.7 Social Implication Of Computer System
The society in which we live has been so profoundly affected by computers that historians refer to the present time as the information age. This is due to the ability to store and manipulate large amounts of information (data) using computers. As an information society, we must consider both the social and ethical implications of our use of computers. By ethical questions we mean asking what are the
morally right and wrong ways to use computers and this could be explain as follows:
Ergonomics: this is the science that studies safe work environments. Many health-related issues, such as carpal tunnel syndrome and computer vision syndrome (CVS), are related to prolonged computer use.
Environmental concern: Power and paper wastes are environmental concerns associated with computer use. Suggestions for eliminating these concerns include recycling paper and printer toner cartridges and turning off monitors and printers when not in use.
Employee monitoring: Employee monitoring is an issue associated with computers in the workplace. It is legal for employers to install software programs that monitor employee computer use. As well, e- mail messages can be read without employee notification. The invasion of privacy is a serious problem associated with computers. Information: Because computers can store vast amounts of data we must decide what information is proper to store, what is improper, and who should have access to the information. Every time you use a credit card, make a phone call, withdraw money, reserve a flight, or register at school, a computer records the transaction. These records can be used to learn a great deal about you—where you have been, when you were there, and how much money was spent. Should this information be available to everyone?
Computers are also used to store information about your credit rating, which determines your ability to borrow money. If you want to buy a car and finance it at a bank, the bank first checks your credit records on a computer to determine if you have a good credit rating. If you purchase the car and then apply for automobile insurance, another computer will check to determine if you have traffic violations.
The Ethical Responsibilities of an IT Professional
IT (information technology) professional has responsibilities that relate to system reliability. System reliability involves installing and updating appropriate software, keeping hardware working and up- to-date and maintaining databases and other forms of data. Professional ethics helps a professional choose what to do when faced with a problem at work that raises a moral issue. One can certainly study what professionals do when faced with such problems, and confine the enquiry to the description. Our concern here, however, is to assist with making choices – an approach called prescriptive professional ethics.
Governments, schools, and employers rely on IT professionals to maintain their computer systems. In addition to ensuring system reliability, an IT professional must take responsibility for the ethical aspects of the career choice. The lists below are the most commonly reported behaviors IT professional which is unethical;
Plagiarism
Failure to protect confidential data
Failure to share credit on a report
Fabrication of data
Criticize the ability/integrity of colleague for own gain
Holding back or disguising data
Design of sampling strategy to favor a specific outcome
Destruction of data that contradicts desired outcome
1.1 I Information Communication Technology Versus Information System
information and Communications Technology or (ICT), is often used as an extended synonym for information technology (IT), but is a more specific term that stresses the role of unified communications and the integration of telecommunications (telephone lines and wireless signals), computers as well as
necessary enterprise software, middleware, storage, and audio-visual systems, which enable users to access, store, transmit, and manipulate information. The term ICT is now also used to refer to the convergence of audio-visual and telephone networks with computer networks through a single cabling or link system. There are large economic incentives (huge cost savings due to elimination of the telephone network) to merge the audio-visual, building management and telephone network with the computer network system using a single unified system of cabling, signal distribution and management.
The term Infocommunications is used in some cases as a shorter form of information and communication(s) technology. In fact Infocommunications is the expansion of telecommunications with information processing and content handling functions on a common digital technology base.
Information technology (IT) is the application of computers and telecommunications equipment to store, retrieve, transmit and manipulate data, often in the context of a business or other enterprise. The term is commonly used as a synonym for computers and computer networks, but it also encompasses other information distribution technologies such as television and telephones. Several industries are associated with information technology, such as computer hardware, software, electronics, semiconductors, internet, telecom equipment, e-commerce and computer services.
In a business context, the Information Technology Association of America has defined information technology as “the study, design, development, application, implementation, support or management of computer-based information systems”. The responsibilities of those working in the field include network administration, software development and installation, and the planning and management of an organization‘s technology life cycle, by which hardware and software is maintained, upgraded, and replaced.
Yekini and Lawal (2012) Sees ICT as: a powerful collection of elements which include computer hardware, software, telecommunication networks, workstations, robotics and smart chips, which is also at the root of information systems
1.2 Information System (IS)
An information system (IS) is the study of complementary networks of hardware and software that people and organizations use to collect, filter, process, create, and distribute data. The study bridges business and computer science using the theoretical foundations of information and computation to study various business models and related algorithmic processes within a computer science discipline. Computer Information System(s) (CIS) is a field studying computers and algorithmic processes, including their principles,
their software and hardware designs, their applications, and their impact on society while IS emphasizes functionality over design.
Any specific Information System aims to support operations, management and decision making. In a broad sense, the term is used to refer not only to the information and communication technology (ICT) that an organization uses, but also to the way in which people interact with this technology in support of business processes.
Some authors make a clear distinction between information systems, computer systems, and business processes. Information systems typically include an ICT component but are not purely concerned with ICT, focusing instead on the end use of information technology. Information systems are also different from business processes. Information systems help to control the performance of business processes.
An information system is a special type of work system. A work system is a system in which humans and/or machines perform work using resources to produce specific products and/or services for customers. An information system is a work system whose activities are devoted to processing (capturing, transmitting, storing, retrieving, manipulating and displaying) information.
An information system is a form of communication system in which data represent and are processed as a form of social memory. An information system can also be considered a semi-formal language which supports human decision making and action.
There are various types of information systems, for example: transaction processing systems, office systems, decision support systems, knowledge management systems, database management systems, and office information systems.
Critical to most information systems are information technologies, which are typically designed to enable humans to perform tasks for which the human brain is not well suited, such as: handling large amounts of information, performing complex calculations, and controlling many simultaneous processes.
“Information systems specialists are the people that integrate information technology solutions and business processes to meet the information needs of businesses and other enterprises.
Silver et al. (1995) provided two views on IS that includes software, hardware, data, people, and procedures. A second managerial view includes people, business processes and Information Systems.
1.3 ICT Literacy
Since we live in information society, everyone is expected to be ICT literate. The ICT literacy entails.
Awareness: As you study computers, you will become aware of their importance, versatility, pervasiveness, and their potential for good and ill in our society.
Knowledge: You will learn what computers are and how they work. This requires learning some technical jargons that will help you deal with the computer and with people that work with computers.
Interaction: This implies learning to use a computer to perform some basic tasks or applications.
1.4 Impact Of ICT On Society
There are both positive and negative impacts of ICT in this modern society. Some these impact are discussed below:
1.4.1 Positive Impacts
Faster Communication Speed: In the past, it took a long time for any news or messages to be sent. Now with the Internet, news or messages are sent via e-mail to friends, business partners or to anyone efficiently. With the capability of bandwidth, broadband and connection speed on the Internet, any information can travel fast and at an instant. It saves time and is inexpensive.
Lower Communication Cost: Using the Internet is cost- effective than the other modes of communication such as telephone, mailing or courier service. It allows people to have access to large amounts of data at a very low cost. With the Internet we do not have to pay for any basic services provided by the Internet. Furthermore, the cost of connection to the Internet is relatively cheap.
Reliable Mode of Communication: Computers are reliable. With the internet, information could be accessed and retrieved from anywhere and at any time. This makes it a reliable mode of communication. However, the input to the computer is contributed by humans. If the data passed to the computer is faulty, the result will be faulty as well. This is related to the term GIGO. GIGO is a short form for Garbage In Garbage Out. It refers to the quality of output produced according to the input. Normally bad input produces bad output.
Effective Sharing of Information: With the advancement of ICT, information can be shared by people all around the world. People can share and exchange opinions, news and information through discussion groups, mailing list and forums on the Internet. This enable knowledge sharing which will contribute to the development of knowledge based society.
Paperless Environment: ICT technology has created the term paperless environment. This term means information can be stored and retrieved through the digital medium instead of paper. Online communication via emails, online chat and instant messaging also helps in creating the paperless environment.
Borderless Communication: Internet offers fast information retrieval, interactivity, accessibility and versatility. It has become a borderless source for services and information.
Through the Internet, information and communication can be borderless.
Create Employment: Although many employment areas have suffered job losses, other areas have grown and jobs have been created. Some examples of areas where jobs have been created: IT Technicians: All of the computers in a business need to be maintained: hardware fixed, software installed, etc. IT technicians do this work. Computer Programmers: All of the software that is now used by businesses has to be created by computer programmers. Hundreds of thousands of people are now employed in the ‘software industry‘ Web Designers: Much of modern business is conducted on-line, and company websites are very important. Company websites need to be designed and built which is the role of web designers.
1.4.2 Negative Effects
Individualistic and introvert: Nowadays, people tend to choose online communication rather than having real time conversations. People tend to become more individualistic and introvert.
Moral decedent and threats to the society: Some ICT users use ICT tools for, fraud, identity theft, Pornography, Hacking etc. That could result to a moral decedent and generate threats to the society.
Health Problems: A computer may harm users if they use it for long hours frequently. Computer users are also exposed to bad posture, eyestrain, physical and mental stress. In order to solve the health problems, an ergonomic environment can be introduced. For example, an ergonomic chair can reduces back strain and a screen filter is used to minimize eye strain.
Unemployment Situation: Some jobs have been lost as a result of computers being used to do the same work that
people used to do, for examples: Manufacturing: Many factories now have fully automated production lines. Instead of using people to build things, computer-controlled robots are used. Robots can run day and night, never needing a break, and don‘t need to be paid! (Although the robots cost a lot to purchase, in the long-term the factory saves money.) Secretarial Work: Offices used to employee many secretaries to produce the documents required for the business to run. Now people have personal computers, they tend to type and print their own documents. Accounting Clerks: Companies once had large departments full of people whose job it was to do calculations (e.g. profit, loss, billing, etc.) .A personal computer running a spreadsheet can now do the same work. Newspaper Printing: It used to take a team of highly skilled printers to typeset (layout) a newspaper page and to then print thousands of newspapers. The same task can now be performed far more quickly using computers with DTP software and computer-controlled printing presses.
ఒక కుటుంబంలో తాతయ్య, నానమ్మ, అమ్మ, నాన్న, అన్నయ్య, తమ్ముడు, అక్క, చెల్లి మొదలైనవారు ఉంటారు.
అన్నదమ్ములు, అక్కచెల్లెళ్ళని “తోబుట్టువులు” అంటారు.
కుటుంబంలో ప్రతి ఒక్కరు ఒకరికొకరు సాయం చేసుకుంటూ ఇంటిపనులు నిర్వహిస్తారు.
పెద్దవారు చిన్నవారి పట్ల ప్రేమగా ఉంటూ భద్రత కల్పిస్తారు.
మన గ్రామంలో వివిధ వృత్తి పనులు చేసేవారు ఉంటారు. ఆదాయం కోసం నైపుణ్యంతో చేసే పనులు “వృత్తులు”.
కుటుంబ పేద పరిస్థితుల కారణంగా కొందరు పిల్లలు బడికి వెళ్లలేని స్థితి ఉంటుంది – బడిబయట పిల్లలు.
సాధారణంగా కుటుంబ సభ్యులు పెద్దవారి పోలికలతో ఉంటారు. తమ ప్రవర్తనలో కూడా వారిని అనుసరిస్తూ ఉంటారు.
పిల్లలు రంగు, ఎత్తు వంటివి తల్లిదండ్రుల నుండి సంక్రమిస్తాయి.
మనచుట్టూఉన్నమొక్కలు
మొక్కలకి వేర్లు, కాండం, ఆకులు, పువ్వులు, కాయలు మొదలైన భాగాలు ఉంటాయి.
వేర్లు నేల దిగువన ఉంటాయి. ఇవి మొక్క భాగాలు అన్నింటిలో ముఖ్యమైనవి. నేలలో లవణాలు, నీరు పీల్చుకుని మొక్క కాండం, ఆకులకి పంపుతాయి.
వేర్లు పీల్చుకున్న లవణాలు, నీరును కాండం మొక్కలో వివిధ భాగాలకి అందిస్తుంది. మొక్కకి ఊతం ఇస్తుంది.
టమాటా మొక్క కాండం సన్నగా ఉంది నూగుగా ఉంటుంది. కాండాలు వివిధ రకాలుగా ఉంటాయి. కొన్ని మెత్తగా ఆకుపచ్చ రంగులో ఉంటాయి. కొన్ని గట్టిగా గోధుమ రంగులో ఉంటాయి. కొన్ని లావుగా ఉంటాయి.
మొక్క పెద్దయ్యే కొద్దీ కొన్ని కాండాలు బలంగా మారతాయి. ఈ బలమైన కాండాన్ని “మ్రాను” అంటారు. మ్రానులు బెరడుతో కప్పి ఉంటాయి.
పెద్దగా, బలంగా ఉండే మొక్కలు – చెట్లు
ఉదా : మర్రిచెట్టు, చింత చెట్టు
గట్టి కాండం కలిగి గుబురుగా పెరిగి మొక్కలు – పొదలు
ఉదా : గులాబీ, మందార
మెత్తగా ఆకుపచ్చ కాండాలు గల మొక్కలు – గుల్మాలు
ఉదా : తులసి, గోధుమ
ఏదైనా ఒక ఆధారం పట్టుకుని పెరిగే మొక్కలు – ఎగబ్రాకే మొక్కలు
ఉదా : ద్రాక్ష, కాకర
నేలపై పాకుతూ పెరిగే మొక్కలు – పాకే మొక్కలు
ఉదా : పుచ్చకాయ, గుమ్మడికాయ
ఆకులు మొక్కలకి కావాల్సిన ఆహారం తయారుచేస్తాయి. ఆకులు ఆహార కర్మాగారాలు. ఇవి ఆహారం గాలి, నీరు, సూర్యరశ్మి సాయంతో తయారుచేస్తాయి.
అరటి ఆకులు – పెద్దవిగా
మందార – వెడల్పు, రంపపు ఆకారం అంచు
బొప్పాయి – హస్తం ఆకారం
కొబ్బరి – పొడవు ఈనెలు
చింత – చిన్న ఆకులు
పుదీనా, కొత్తిమీర, తులసి – మంచి వాసన కలవి
కొత్తిమీర, మునగాకు, కరివేపాకు మొదలైన ఆకులు తింటాం.
తేయాకు – టీ
వేపాకు, తులసి – వైద్యం
అరటి, మర్రి ఆకులు మొ. – విస్తర్లు, పాత్రలు తయారీ.
రాలి పడిన ఆకులు ఎరువుల తయారీలో వాడతారు.
మొక్కలు కార్బన్ డై అక్సైడ్ పీల్చుకుని ఆక్సిజన్ మనకి ఇస్తాయి.
పెద్ద మొక్క వేర్లు నేలలో బలంగా చొచ్చుకుపోవడం వల్ల భూసార నష్టం కాకుండా కాపాడతాయి.
మనచుట్టూఉన్నజంతువులు
మన ఇళ్లల్లో మనతో పాటు నివసించే పిల్లులు, కుక్కలు మొదలైన జంతువులు – పెంపుడు జంతువులు
ఆవులు పాలు ఇస్తాయి. ఎద్దులు, దున్నలు వ్యవసాయ పనుల్లో సహాయ పడతాయి. కోడిపెట్ట, బాతు గుడ్లు పెడతాయి. మేకలు పాలు, మాంసం ఇస్తాయి. గుర్రాలు, గాడిదలు బరువులు మోస్తాయి. ఇవి అన్నీ కూడా మచ్చిక చేసుకునే జంతువులు.
అడవుల్లో నివసించే పులి, సింహం మొదలైనవి – వన్య మృగాలు
జంతువులు వివిధ ప్రదేశాల్లో నివసిస్తాయి. కొన్ని చెట్లపైన, కొన్ని నీటిలో, కొన్ని నేల మీద నివసించును.
నేల మీద నివసించేవి – భూచర జీవులు. ఆవు, కుక్క, కోడి మొదలైనవి.
నీటిలో నివసించేవి – జలచర జీవులు. పడవ ఆకారం శరీరం, వాజాలు, మొప్పలు, తోక నీటిలో నివసించడానికి వీటికి సహాయపడెను. ఉదా. చేపలు
నేల మీద, నీటిలో నివసించేవి – ఉభయచరాలు. తేమగా ఉండే చర్మం, వేళ్ళ మధ్య చర్మం, బలమైన వెనుక కాళ్ళు అనేవి వీటికి నేలమీద, నీటిలో నివసించడానికి సహాయం చేస్తాయి. ఉదా. కప్ప, సాలమండర్
మొక్కల నుండి లభించే ఆహార పదార్ధాలను తినేవి – శాఖాహారులు. ఉదా. ఆవు, గుర్రం, జింక, ఏనుగు మొదలైనవి.
ఉడుతలు కాయలు, గింజలు తింటాయి.
ఇతర జంతువుల మాంసం తినేవి – మాంసాహారులు. ఉదా. పులి, సింహం, నక్క
వడ్రంగి పిట్ట – చెట్టు కాండాలకి పెద్ద తొర్రలు చేసి నివాసం ఉంటుంది.
గిజిగాడు – చెట్లు చిగురుల్లో గడ్డి, కర్రపుల్లలు ఉపయోగించి గూడు కట్టెను. క్రింది వైపు ప్రవేశించడానికి ఒక ద్వారం ఏర్పరుచుకుంటుంది.
ఊరికిపోదాం
బస్సులు నిలుపు స్థలం – బస్టాండ్.
బస్సు కోసం వేచి ఉండడానికి, కూర్చోడానికి అనువైన స్థలం – ఫ్లాట్ ఫారం.
రోడ్డు తయారీకి వాడే పదార్ధాల బట్టి రోడ్డులు ఆరు రకాలు. అవి మట్టిరోడ్డు, గ్రావెల్ రోడ్డు, ఎర్రమట్టి రోడ్డు, గ్రానైట్ రోడ్డు, తారు రోడ్డు, కాంక్రీట్ రోడ్డు.
ప్రయాణీకుల అవగాహన కోసం, ప్రమాదాలు జరగకుండా, ట్రాఫిక్ అసౌకర్యాలు అరికట్టడానికి వివిధ సూచికలు తెలిపే బోర్డులు వాడతారు.
సిగ్నల్ లైట్స్ : ఎరుపు – ఆగడం, పచ్చ – వెళ్లడం, ఆరెంజ్ – సిద్ధంగా ఉండుట
వాహనాలు నడపడానికి పెట్రోల్, డీజిల్, CNG వంటి ఇంధనాలు వాడతారు.
మాట్లాడుకుందాం
ఇతరులకు మన భావాలు ఆలోచనలు తెలిపే విధానం – భావ వ్యక్తీకరణ
నృత్య కళాకారులు, మైమ్ కళాకారులు వివిధ రకాల సంజ్ఞల భాష వాడతారు.
నృత్య కళాకారులు భావ వ్యక్తీకరణకి ముద్రలు వాడతారు.
కమ్యూనికేషన్ ముఖ్య ఉద్దేశ్యం మన భావాలు, ఆలోచనలు ఇతరులతో పంచుకోవడం.
భావ వ్యక్తీకరణ రెండు రకాలు. అవి
మౌఖిక సంభాషణ – పరస్పరం మాట్లాడడం
శబ్ద సంభాషణ – హావభావాలు ద్వారా
ప్రత్యక్ష భావ వ్యక్తీకరణ – భావాలు, ఆలోచనలు వారి శరీర కదలికలు ద్వారా వ్యక్త పరచడం.
పురాతన కాలంలో ప్రజలు దూరంగా ఉండేవారితో వారు చెప్పదలచినది డంకా ద్వారా గాని, పొగ ద్వారా సంకేతం ఇవ్వడం, పావురాల ద్వారా లేఖలు పంపడం, గుర్రపు స్వారీ చేయువారు ద్వారా వర్తమానం పంపేవారు.
చెవిటి, మూగ వ్యక్తులు తమ భావాలు వ్యక్తపర్చడానికి సంకేత భాష వాడతారు.
చీమలు తమ కాళ్ళు, తల ద్వారా ఒకదానితో ఒకటి భావాలు వ్యక్తపరుస్తాయి.
దృశ్య భావ వ్యక్తీకరణ :
తాబేలు, నత్తలు బెదిరింపుకి గురి అయితే వాటి తల ముడుచుకుంటాయి.
కుక్కలు సంతోషంగా ఉంటే వాటి తల ఊపుతాయి.
శ్రావణ భావ వ్యక్తీకరణ :
ఏనుగులు ఘీంకారం ద్వారా ఇతర గుంపుతో మాట్లాడెను.
ఇతర తోడేళ్లను పిలవడానికి తోడేళ్ళు ఊళ వేస్తాయి.
రసాయన భావ వ్యక్తీకరణ :
పిల్లులు తమ వాసన గుర్తించుటకు వస్తువుల మీద రుద్దెను.
పాములు, కుక్కలు శత్రువులు గుర్తించుటకు వాసన జ్ఞానం ఉండెను.
స్పర్శ ద్వారా భావ వ్యక్తీకరణ :
కుక్కలు, పిల్లులు తమ ప్రేమ వ్యక్త పరచడానికి పిల్లలను నాకుతాయి.
కోతులు, బబూన్ లు ఒకదానితో ఒకటి ప్రేమ కనబరచడానికి దువ్వుతాయి.
“వాగల్ డ్యాన్స్” అనేది తేనెటీగలలో ఒక రకమైన దృశ్య భావ వ్యక్తీకరణ. కూలీ తేనెటీగలు ఆహారం యొక్క సమాచారం నాట్యం ద్వారా తెల్పును.
ఆటలు – వినోదం
ఆటలు అనేవి వినోదాత్మకం
లోపల ఆడే ఆటలు – ఇండోర్ గేమ్స్. అష్టా చెమ్మా, చదరంగం, పులి-మేక, వామన గుంతలు, గుచ్చం గాయలు, చైనీస్ చెక్కర్స్, టేబుల్ టెన్నిస్ మొదలైనవి.
ఖాళీ ప్రదేశాల్లో, క్రీడా మైదానంలో ఆడే ఆటలు – అవుట్ డోర్ గేమ్స్. కబడ్డీ, ఖోఖో, ఫుట్ బాల్, టెన్నిస్, టెన్నికాయిట్, క్రికెట్ మొదలైనవి.
ఆనందం కోసం, మన శరీరం తేలికగా ఉండడం కోసం చేయు క్రియ – వినోదం. చదవడం, ఆటలు, సంగీతం వినడం, తోటపని, ప్రయాణం మొదలైనవి.
పార్కులు, బీచ్ లు కొన్ని వినోదం కలిగించే ప్రదేశాలు.
మన రాష్ట్ర క్రీడ – కబడ్డీ (చెడుగుడు), జాతీయ క్రీడ – హాకీ
పల్లెల్లో పిల్లలు వివిధ ఆటలు ఆడతారు. ఏడు పెంకులాట, కోతి కొమ్మచ్చి, బొంగరాలు ఆట, పులి మేక, ముక్కు గిల్లే ఆట, తొక్కుడు బిళ్ళ, నేల – బండ, కర్ర – బిళ్ళ మొదలైనవి. వీటిని “ప్రాంతీయ క్రీడలు” అంటారు.
మనం ఆటలు ఆడేందుకు కొన్ని పరికరాలు, ఆట సామగ్రి అవసరం
టెన్నికాయిట్ – రింగ్ బాల్, తాడు
క్రికెట్ – బ్యాట్, బాల్, స్టంప్స్
పిల్లల అటల సమయం – సాయంత్రం 4 నుండి 6 గం.
ఆటల వల్ల ఆనందం, ఆరోగ్యం కలిగెను.
పరస్పర సహకారం, ఐక్యత, పరస్పర అవగాహన, నాయకత్వ లక్షణాలు అభివృద్ధి చెందును.
జట్టులో ఆటగాళ్లు పరస్పరం ఒకరిని ఒకరు సహకరించుకోవడం – బృంద స్ఫూర్తి
దిక్కులు – మూలాలు
మన సమీప ప్రాంతంలో సౌకర్యాలు మన జీవితాలను సౌకర్యవంతం చేయును.
సూర్యుని ఎదురుగా నిలబడితే – ఎదురుగా ఉండేది తూర్పు, వెనుక పడమర, ఎడమ – ఉత్తరం, కుడి – దక్షిణ
అన్ని దిక్కులు స్థిరం. ఉత్తరం నుండి లెక్కించబడెను.
ఒక ప్రాంతం/ఊరు హద్దులు – సరిహద్దులు
రెండు దిక్కుల మధ్య ప్రాంతం – మూల
తూర్పు – ఉత్తర మధ్య — ఈశాన్యం
తూర్పు – దక్షిణ మధ్య — ఆగ్నేయం
పడమర – ఉత్తర మధ్య — వాయువ్యం
పడమర – దక్షిణ మధ్య — నైఋతి
పురాతన కాలంలో నావికులు సూర్యుడు, నక్షత్రాలు, పవనాలు దిశ బట్టి దిక్కులు కనుగొనేవారు.
నేడు దిక్సుచి, GPS ద్వారా దిక్కులు కనుగొంటున్నాం.
GPS – GLOBAL POSITIONING SYSTEM
ఒక ప్రాంత సమీపంలో తెలిసిన ప్రదేశాలను “గుర్తింపు చిహ్నాలు” అంటారు.
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