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The computer will work according to the instructions given to it. We can use the generic term computer program to refer any piece of software. Some software are specially designed for the primary functions of the computer to manage its operations while some software are designed for the users to get their work done, ex.
However, software can be categorized into different categories and you will learn deeply about software in Session 04 of this course material. This information may be in the form of text, documents, images, audio clips or software program. The primary use of the computer is to convert these data into useful information to the user. The computer accepts data from some sources or from the user to produce useful information. Thus the raw data fed into the computer may not make much sense to the users until it is processed.
You may think whether a user is essential as you might have seen some performs their job without a person sitting in front of the computer. But you should not forget that the people design and build the programs running on it. The people do repairs to computer systems when needed.
Therefore, User is an essential part of a computer system. Further, you will learn about the applications that you can run in Personal computers within this course material. Hardware b. Software 2. Briefly describe them. Briefly describe three.
Describe what hardware is Classify computer hardware according to the usage of them Give examples for each category of computer hardware Identify the different ports of a PC Identify why your computer is slow Identify the factors affecting on performance of computers.
You are already aware that a computer system is made up of several different components. Those that can be seen and touched are referred to as the Computer Hardware or simply hardware.
In other words, the physical equipments that are involved in the function of the computer are called its hardware. The following diagram Figure 3.
Computer Hardware. Figure 3. The Central Processing Unit is an electronic device which runs computer programs: a set of sequential instructions. It is also called as the Computer Processor or the brain of the computer. According to the above Figure 3. The CU is the circuitry that controls the flow of data through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC.
The ALU is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one, for purposes such as maintaining timers. We consider the CPU as the processing device of the computer. These two components work together to perform the processing operations. Let us talk about the above sub parts briefly. The Control Unit CU As you know, a computer program or set of instructions must be stored in memory for a computer to process data.
Further, the CU directs and coordinates most of the operations of the computer. The speed at which the processor. The higher the number of MHz the faster the computer can process information. The Intel i7, Athlon, Celron, and Duron, Ultra Spark are some examples for the brands of processors available in the market.
The size of the memory is measured by the number of bites available. The following equalities give the measuring units of the memory. The data and the instructions needed by the CPU are temporarily stored in the Memory.
Therefore the memory acts as the internal storage of a computer. The programs that are stored in external storages are loaded into the memory before they start running. The memory of a computer may be either volatile or non-volatile. If the data will be lost as soon as the power is turned off the computer, then this type of memory is said to be Volatile.
This small memory is capable of memorizing temporarily. It can be read and written. The programs which are needed to start up your computer Ex: to boot the computer are stored in ROM. Memory cache, also called a cache store or RAM cache, helps speed the processes of the computer by storing frequently used instructions and data thus reducing the access time of data. When the processor needs an instruction or data, it first searches in the cache. A computer executes instructions and processes data into information and stores the information for future use.
Input devices are used to enter instructions and data into the computer. Input is any data or instructions you enter to the memory of a computer. Once input is in memory, the CPU can access it and process the input into output. There are four types of input namely: data, programs, commands, and user responses. A computer manipulates and processes data into information, which is useful. Note: Although technically speaking a single item of data should be called a datum, the term data is commonly used and accepted as both the singular and plural form of the word.
Programs respond to commands issued by the user. Commands can be issued by typing keywords or pressing special keys on the keyboard. A keyword is a specific word, phrase, or code that a program understands as an instruction. Some keyboards include keys that send a command to a program when you press them.
Instead of requiring you to remember keywords or special keys, many programs allow you to issue commands by selecting menu choices or graphical objects. For examples, programs that are menu driven provide menus as a means of providing commands. Today, most programs have a graphical user interface GUI that uses icons, buttons, and other graphical objects to issue commands. However, GUI is the most user friendly way to issue commands. For example, Do you want to save the changes you made?
Based on the response given by the user, the program performs certain actions. In this example, if the answer was Yes, then the program saves all changes you made to the file on the storage device. Some of the commonly used input devices are listed below. It is a text based input device that allows the user to input alphanumeric characters and some other special characters.
The keyboard is consisting of a set of keys mounted on a board. Each key or button acts as an electronic switch corresponding to a symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence; other keys do not produce any symbol, but instead affect the operation of the computer or the keyboard itself.
Physically, a mouse consists of a small case, held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features can add more control or dimensional input.
The mouse's motion typically translates into the motion of a pointer on a display, which allows for fine control of a Graphical User Interface. Furthermore, a mouse is an input device that allows the user to point and click or drag and drop. Common functions are pointing moving the cursor or arrow on the screen by sliding the mouse on the mouse pad , clicking using the left and right buttons and scrolling hold down the left button while moving the mouse.
The resulting image can be of different qualities depending on the resolution of the scanner. The Flat-bed scanner is the most popular scanner which is similar to a photo copy machine except that it creates a file softcopy of the document instead of a paper copy hardcopy. The file that contains the scanned object can be stored on an external storage device, displayed on the screen, printed, faxed, sent via e-mail, or included in another document.
Most items in shops, special in super markets in Sri Lanka have a bar code printed or affixed on them. The Bar code is a trip of vertical bars of varying widths that creates a unique reference for the particular item. Groups of bars represent individual digits and most bar codes are made up of digits. The last number is a check digit and it is used to verify that the number has been scanned in correctly. The computer applies a set of calculations to the individual digits and the answer should equal to the last check digit.
Bar code reader uses a visible red light to scan the bar code and it is interpreted through a decoder. The reference is matched with the stock list in the computer system to find the appropriate price.
Sometimes, numbers are printed below the vertical stripes which are to be used in cases the bar code reader fails to read the code. When text documents are scanned, they are scanned and saved as pictures in the computer.
Output is data that has been processed into a useful form called information. A computer processes input into output.
Computers generate several types of output, depending on the hardware and software being used and the requirements of the user. You may choose to display or view this output on a monitor, print it on a paper using a printer, or listen to it through speakers or a headset. Accordingly the four common types of output are text, graphics, audio, and video. A brief description on each of output type is given below.
Text Text consists of characters that are used to create words, sentences and paragraphs. A character can be a letter, number, punctuation mark, or any other symbol that requires one bite of computer storage space. Graphics Graphics are digital representations of non-text information such as drawings, charts, pictures and photographs.
Graphics also can be animated, giving them the illusion of motion. Animations are created by displaying a series of still images in rapid sequence. Many of todays software programs support graphics. For example, you can include a photograph in a word processing document or create a chart of data in a spreadsheet program.
Some software packages are specifically designed to edit graphics. Audio Audio is Music, speech, or any other sound. You might have learnt at school that sound waves, such as the human voice or music are analog. To store such sounds, a computer converts the sounds from a continuous analog signal into a digital format.
Most output devices require that the computer converts the digital format back into analog signals. Video often is captured with a video input device such as video camera or VCR. Most video signals are analog; however, most of the modern video devices record the video images digitally. A video capture card converts an analog video signal into a digital signal that a computer can understand. The digital signal then is stored on the computers hard disk.
Some output devices accept the digital signal, while others require that the computer converts the digital signals back into analog signals. Some commonly used output devices are listed below. Therefore, let us look at some general facts about these categories of output devices. Monitor The monitor displays the output to the user visually.
The monitor looks like a television, but they often have higher resolutions than a normal television. Similar to televisions, the sizes of monitors are varying and often expressed in diagonally measured distance in inches. The technology used with monitors is expanding rapidly and there are two major types of monitors that differ in the technology of visualizing the output to the user.
The CRT monitor has more lines of dots per inch, higher the lines more amount of the resolution. It creates the picture by number of rows or lines of the small tiny dots. For an instance the resolution of x will be sharper than x resolutions. The LCD consists of two sheets of polarizing material with a liquid crystal solution between.
When an electric current passed through the liquid crystal solution, crystals align so that light cannot pass through them. It is like a shutter either allows light to pass through or blocking the light.
The LED is the latest marketing innovation of display units. It looks similar to LCD and it is also a flat panel display. The way the backlight works however with the LED's will lead to a number of improvements in the display. Many printers are primarily used as local computer peripherals, and are connected by a printer cable to a computer which serves as a document source.
Some printers, commonly known as network printers can serve as a hardcopy device to be shared and used by any user among a group of users connected to the network. Individual printers are often designed to support both local and network connected users at the same time. Ex: Impact printers Ex. Impact Printers Any impact printer forms characters and graphics on a piece of paper by striking a mechanism against in an ink ribbon that physically contacts the papers.
Because of the striking activity, impact printers generally are noisy. Many impact printers do not provide letter-quality print. Letter-Quality LQ output is a quality of print acceptable for business letters. Many impact printers produce near letter-quality NLQ. NLQ impact printers are used for jobs that require only NLQ, such as printing of mailing labels, envelopes, or invoices. Impact printers are also ideal for printing multipart forms because they easily can print through many layers of paper.
Finally, impact printers are used in many factories and retail counters as they can survive in dusty environments, vibrations, and extreme temperatures. Non-Impact Printers A non-impact printer forms characters and graphics on a piece of paper without actually striking the paper.
Some spray ink, while others use heat and pressure to create images. Since these printers do not strike the paper, they are much quieter than the above impact printers. See figures from 3. Plotter Plotters are special type of printers used to print graphical output on paper. It interprets computer commands and makes line drawings on paper using multicolored automated pens. The plotter is capable of producing graphs, drawings, charts, maps, illustrations etc.
For an example, consider the touch screen which is a type of monitor that displays text or images you can touch using your figure tips. Touching different locations determines different information to be displayed next or what action to be taken next. Thus this touch screen see Figure 3. Storage refers to the media on which data, instructions, and information are kept, as well as the devices that record and retrieve these items. In this section we will discuss about the storage media and storage devices.
Memory holds data and instructions temporarily while they are being processed by the CPU. Storage, also called Secondary, Auxiliary storage, or Mass storage, holds items such as data, instruction, and information for future use. Think of storage as a filing cabinet used to hold file folders, and memory as the top of your desk.
When you need to work with a file, you remove it from the filing cabinet storage and place it on your desk memory. When you are finished with the file, you return it to the filing cabinet.
A storage medium is the physical material on which the items are kept. One commonly used storage medium is a disk, which is round, flat piece of plastic or metal with a magnetic coating on which items can be written. A storage device is the mechanism used to record and retrieve items to and from a storage medium.
Storage devices can function as source of input and output. For example, each time a storage device transfers data, instructions, and information from a storage medium into memory a process called Reading ; it functions as an input source. When a storage device transfers these items from memory to a storage medium a process called Writing , it functions as an output source.
Compared to memory, storage devices are slow. The access time of memory devices are measured in milliseconds. However, you may already have some idea about them. Floppy disks A floppy disk is a data storage medium that is composed of a disk of thin, flexible floppy magnetic storage medium encased in a rectangular plastic shell.
Floppy disks are read and written by a floppy disk drive. Application Any use where small files such as word processing, small spread sheets and databases need to be moved from one computer to another. Useful to backup small data files. Fixed hard disks A hard disk drive is the device used to store large amounts of digital information in computers and related equipment like iPods and games consoles such as the Xbox and PS3.
Hard disk drives are used to store operating systems, software and working data. These are suitable for any application which requires very fast access to data for both reading and writing to. However, Hard disk drives may not be suitable for applications which need portability.
Almost all computers used a fixed hard disc. Used for on-line and real time processes requiring direct access. Used in file servers for Figure 3. Hard Disk drive which is often referred to as Hard Disk or Hard Drive is a device to store and retrieve data in a computer. The hard drive can store important system files like the operating system, program files and other data. Though HDDs were originally designed to be used with computers nowadays the applications for HDDs have expanded beyond computers to include digital video recorders, digital audio players, personal digital assistants, digital cameras and video game consoles.
HDD is a non-volatile storage device that stores digitally encoded data. It is an electromagnetically charged surface or set of disks that record data in concentric circles known as tracks.
HDDs record data by magnetizing ferromagnetic material directionally, to represent either a 0 or a 1 binary digit. They read the data back by detecting the magnetization of the material.
A typical HDD design consists of a spindle which holds one or more flat circular disks called platters, onto which the data is recorded.
The platters are made from a non-magnetic. Portable Hard Disks Portable hard disk is an interesting and useful device because you can carry data about all over the place and transfer information, programs, pictures, etc.
Modern portable hard disks have a massive capacity like GB. Advantages: Greatly improved data cargo carrying capacity. More expensive than other forms of removable media.
Application Portable discs are used to store very large files which need transporting from one computer to another and price is not an issue. Magnetic tapes Magnetic tape has been used for data storage for over 50 years. When storing large amounts of data, tape can be substantially less expensive than disk or other data storage options.
Tape storage has always been used with large computer systems. Modern usage is primarily as a high capacity medium for backups and archives. Drawbacks Writing and retrieving data is slow. It uses serial access for reading and writing. It is commonly used for backups of file servers for computer networks, in a variety of batch processing applications such as reading of bank cheques, payroll processing and general stock control.
CDs tend to be used for large files but smaller than 1 GB which are too big for a floppy disc to hold such as music and general animation. DVDs are used to hold very large files several GBs such as movie films. Both can be used to store computer data. CDs - recording of music downloads from the Internet, recording of music from MP3 format, recording of data for archiving or backup purposes.
DVDs recording of film movies and television programs. Not suitable for music recording but is very useful for keeping generations of files. DVDs have between five and ten times the capacity of CDs. Solid state backing storage These are the smallest form of memory available in the market today. Widely used as removable storage. They are stronger than other forms of storage. Though expensive than other forms they can be easily written to and updated.
Storage capacities typically range from 64 MB to 64 GB. USB flash drives offer potential advantages over other portable storage devices, particularly the floppy disk. They have a more compact shape, operate faster, hold much more data, have a more durable design, and operate more reliably due to their lack of moving parts.
Flash drives are widely used to transport files and backup data from computer to computer. A memory card or flash memory card is a solid-state electronic flash memory data storage device used with digital cameras, handheld and Mobile computers, telephones, music players, video game consoles, and other electronics.
Some digital gadgets support more than one memory card to Figure 3. With reference to Figure 2. It should be mentioned here that many people use to refer to this as the CPU incorrectly. This erroneous reference may be due to CPU: The brain of the commuter being that significant. However, the electronic devices such as CPU, memory, hard disk drive are located inside the System Unit.
A brief description of each above component is given next. Note: The system unit is also called the housing, case, computer chassis, or cabinet. The motherboard is sometimes called the system board, planner board or main board. It is the main circuit board of a computer. The motherboard contains several connectors for attaching additional boards. All of the basic circuitry and components required for a computer to function are onboard the motherboard or are connected with a cable.
The most important component on a motherboard is the chipset. It often consists of two components or chips known as the Northbridge and Southbridge, though they may also be integrated into a single component. These chips determine, to an extent, the features and capabilities of the motherboard. See Figure 3. All boards will be slightly different as far as which components they have, and the locations of those components may differ, but they are fairly close.
These can be used for components such as Ethernet cards, sound cards, and modems. These are used for your graphics card. With two of them onboard, you can run 2 graphics cards in SLI. These are the 16x speed versions, which are currently the fastest.
These can be used for expansion cards such as Sound Cards, or Ethernet Cards. Northbridge - This is the Northbridge for this motherboard. This connection will come from your Power Supply.
Using this connection over one from your power supply will allow the motherboard to control the speed of your fan, based on the CPU temperature. Socket - This is where your CPU will plug in. The orange bracket that is surrounding it is used for high end heat sink-s. It helps to support the weight of the heat sink. Most boards will have 4 slots, but some will only have 2. Using them this way will give your memory a speed boost.
This is the main power connection for the motherboard, and comes from the Power Supply. Most drives today come with SATA connections, so you may not use this. Front Panel Connections - this is where you will hook in the connections from your case. These are mostly the different lights on your case, such as power on, hard drive activity etc. If you have a floppy disk drive in your computer, this is where you will hook it up.
CMOS battery - This is the motherboard's battery. This is used to allow the CMOS to keep its settings. Usually we connect the power code of the computer to the domestic mains supply. Power supplies have a certain power output specified in Watts, a standard power supply would typically be able to deliver around Watts. Most probably, you might have seen the Compact Disks CDs which are commonly used as a storage media. The CD-ROM drive is a high capacity optical data storage device with a removable disk, it writes data onto or reads data from a storage medium.
Floppy disks were used as a storage medium of which capacity is 1. However, nowadays the floppy disks or diskettes are outdated and USB Flash Disk drives and card readers have now come into play instead of floppy disks. Card reader is a data input device that can read data embedded in plastics cards which come in several forms such as bar codes, magnetic strip, computer chip. This reader may act as a memory card reader, smart card reader, magnetic card reader, or business card reader depending on the card read by the unit.
Following Figure 3. However, it should be noted that there may be new components added with the advent of technology in the PCs what you can find now. We have already dealt about the peripheral devices in previous sections. Here we are going to see how we can connect these peripheral devices to your computer.
Have you ever observed the back panel of the CPU? If you see the back panel of the CPU carefully you will come to know that there are several types of ports. They are in different colures and in different shapes. These ports can be fixed with specific ports from the peripheral devices. Hence ports can be considered as the interface in-between the computer and the peripheral devices. This mechanism is much more similar to a lock and key mechanism.
Now lets take a look at each port individually and it is certainly going to be interesting! Commonly motherboards consist of these ports but this has become phased out because of the usage USB ports to connect these devices.
This is used to connect the parallel devices to the computer. It is often called as Centronics interface after the company that designed the original standard for parallel communication between a computer and printer.
Parallel ports can have 25 connections. Serial port can have either 9 connections or 25 connections. Modem which is used to obtain the Internet connection is an ideal example for serial device. This was common method of data transfer throughout the history of the personal computers. Network equipment such as routers and switches commonly use serial console for configuration.
Serial ports are still used in these areas as they are simple, cheap and their console functions are highly standardized and widespread. A serial port requires very little supporting software from the host system. These 15 pins transmit video signals based on colors and video synchronizing. They give an extra way to maintain an additional external monitor when using laptop.
Using a VGA port is not too complicated, just plug the cable in and turn on the monitor. The existing analog video standards have been replaced with the arrival of HDMI. There are typically at least two USB ports on laptops and four on desktop computers, while USB "hubs" provide more connections there are exceptions as well.
Fire wire Port Firewire is a type of cabling technology for transferring data to and from digital devices at high speed. Some professional digital cameras and memory card readers connect to the computer over FireWire. FireWire card readers are commonly faster than those that connect via USB.
FireWire is one of the fastest peripheral standards ever developed, which makes it great for use with multimedia peripherals such as digital video cameras and other high-speed devices like the latest hard disk drives and printers. It has the bandwidth of megabits per second and the latest machines include FireWire ports operate at around megabits per second.
FireWire is a cross-platform implementation of the high-speed serial data bus which can handle up to 63 on the same bus consisting of simplified cabling and hot swapping. When this port is in use, a little monitoring light flickers. You may be wondering why your computer is slow at times and there are other times when it is fast in processing. This could be caused by a number of factors.
They include: the speed of the CPU, the space on the hard disk, the size of the RAM, the type of the graphics card, the speed of the hard disk, if the computer is multitasking, the defragmenting files. Note that, good computer performance may involve one or more of the following:. Performance of the Microprocessor A microprocessor is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory.
Performance of the Microprocessor is depended on the several factors including;. The clock speed of the CPU is the frequency of which the processor executes instructions or the frequency by which data is processed by the CPU. It is measured in millions of cycles per second or megahertz MHz. If the Clock speed of the CPU is fast then definitely the performance of the computer will be affected positively, in other words the computer will carry out processing functions at a faster pace.
Bus Speed A bus transfers data between components inside a computer. For an example, the processor is connected to the motherboard through the bus called, Front-side bus. The more data a bus can handle at one time, the faster it allows information to travel.
The speed of the bus, measured in megahertz MHz , refers to how much data can move across the bus simultaneously. Number of cores The "core" in a processor is the microprocessor inside of the CPU. For example, if you have an i7 CPU then you have 4 microprocessors inside of the CPU; this allows you to do four things at once, as a microprocessor can only do one thing at a time.
Available features Some latest technologies introduced over the processor technology have increased the performance of the processor. For example, Turbo Boost Technology and the Hyper- Threading Technology For an example, the following list gives some existing features available in the modern Intel i7 microprocessor which has increased its performance.
Cores 4 Threads 8 Clock Speed 3. Performance of the Hardware devices Computer is a digital electronic device, consists of set of electronic circuits Example Motherboard therefore, performance of the hardware devices are dependents on several factors including.
BUS Speed of the system Performance of the available ports Technology used to develop The following figures show the physical architecture of the computer motherboard and the bus system. Performance of the Storage devices To increase the performance of the storage devices, storage system has been divided in to the several units such as;. Primary Memory Secondary Memory Cache memory Accordingly, the performance of the computer goes up if the collective memory Primary, secondary, and Cache is high.
Here, we mainly focus on the device drivers installed into your computer. You should make sure that you have installed drivers recommended by the hardware vendor. You will learn more about the computer software in the next session and you will find what Software Drivers are in that session.
Briefly explain the components of the CPU. Describe the factors which affect the performance of it. How is it measured? Define the following devices. Input devices b. Output devices 3. Using suitable examples, describe the use of bar codes.
Briefly explain the functionality of the following display devices. CRT Monitor b. LCD Monitor 3. Suggest suitable devices for the following.
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