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TOPIC 1: IDENTIFY COMPUTER HARDWARE AND SOFTWARE
Topic content: Concepts of ICT Functions of ICT History of computers Components of a computer Classification of computers
Concepts of ICT Definitions :
A Computer is an electronic device that can perform activities that involve Mathematical, Logical and graphical manipulations.
OR
This is an electronic device that accept data (input), process it into useful information (output) and store for later reuse (retrieve).
Computer system -A system is a group of two or more interrelated components or subsystems that serve a common purpose. A computer system comprises of input, processing, storage and output devices. Data -This refers to a collection of disorganized figures, facts, statistics, opinions or predictions that are not useful for decision making. Also refers to the raw facts which have not been processed
Information - This is processed data which is in a form that is meaningful for decision making Information production is a cycle of input, processing and output as shown in the diagram below. Program : Set of instructions that enables a computer to perform a given task.
Information Communication Technology -This is the integration of computers, telecommunication and other technologies applied to the collection, storage, processing of data and dissemination of information to decision makers.
Charecteristics of computers:
- High speed: Computers have the ability to perform routine tasks at a greater speed than human beings. They can perform millions of calculations in seconds.
- Accuracy: Computers are used to perform tasks in a way that ensures accuracy.
- Storage: Computers can store large amount of information. Any item of data or any instruction stored in the memory can be retrieved by the computer at lightning speeds.
- Automation: Computers can be instructed to perform complex tasks automatically ( which increases the productivity).
- Diligence: Computers can perform the same task repeatedly & with the same accuracy without getting tired.
- Versatility: Computers are flexible to perform both simple and complex tasks.
- Cost effectiveness: Computers reduce the amount of paper work and human effort, thereby reducing costs. Limitations of computers:
- Computers need clear & complete instructions to perform a task accurately. If the instructions are not clear & complete, the computer will not produce the required result.
- Computers cannot think.
- Computers cannot learn by experience.
Functions of ICT It increases operational efficiency Enhances employee productivity Improves customer service
Increases customer satisfaction Promote effective decision making Enables development of competitive products Enables Strategic Planning for future expansion
Advantages of computer systems High speed processing A super computer can process one trillion arithmetic operations in one second. Handle large volume of repetitive tasks It can prepare a payroll by calculating hours worked, rate per hour, total wages, various deductions and net wages for thousands of employees without getting bored. Has logical ability Able to distinguish between numbers and decide which one is greater, negative or positive Remote processing Through time sharing and telecommunication, many persons at different locations can use the same computer at one location for information processing eg ATM banking or air-time top up. Enhance productivity Productivity increase once workers learn to use computers to perform their duties better and faster Accelerate decision making Managers can sort issues faster and make better decisions Reduce operation costs Computers help to hold down the costs of labour, energy and paper work Reduce storage space Information can be stored in computer components which occupy smaller space unlike paper
Disadvantages of computers High initial costs-requires high initial cost to purchase and install the computers Require skilled operators-Training needs to be done for the computer operators Cause health problems-use of computers causes health related problems such as neck ache, eyes Reduce employment opportunities-one computer can perform several tasks that could have been performed by several people hence causes unemployment Greater loss of data in case of breakage or system failure
HISTORY/GENERATION OF COMPUTERS First Generation The period 1940 to 1956, roughly considered as the First Generation of Computer. The first generation computers were developed by using vacuum tube or thermionic valve machine. The input of this system was based on punched cards and paper tape; however, the output was displayed on printouts.
Application They were used for scientific applications as they were the fastest computing device of their time. Examples UNIVersal Automatic Computer (UNIVAC), Electronic Numerical Integrator And Calculator (ENIAC), and Electronic Discrete Variable Automatic Computer (EDVAC).
Second generation computer The period 1956 to 1963 is roughly considered as the period of Second Generation of Computers. The second generation computers were developed by using transistor technology. In comparison to the first generation, the size of second generation was smaller. In comparison to computers of the first generation, the computing time taken by the computers
Super computers- They are the fastest, largest, most expensive and powerful computers. Mainly used in scientific research, simulation, weapon, analysis etc. Mainfram e- They are less powerful and less expensive than the super computers. It finds its application in government agencies, big companies e.g. bank, hospital etc. Mini computers- They are physically smaller and cheaper than mainframes. They are used in research institutions, scientific laboratories etc Micro computers- The smallest, cheapest and least powerful type of computers. It‟s called a microcomputer because its CPU is called a microprocessor. They are used mainly in learning institutions.
Examples of micro computers
2 According to Functionality
- Analog computers – They process data which is continuous in nature. They perform arithmetic operations and logical comparisons by measuring changes in physical magnitude e.g. speed, temperature etc
- Digital computers – They process data which is discrete in nature. Their operations are based on two states namely “on” and “off” or “I” and “O”.
- Hybrid computers – they are computers which are built with the characteristics of both analog and digital computers.
3 According to Purpose
- General purpose – they are designed to be able to perform a variety of tasks.
- Special purpose – they are designed to serve a specific purpose e.g. robots used in industries, mobile phone for communication only etc.
- Dedicated – they are general purpose computers that are committed to some processing task e.g. dedicated to word processor tasks only.
Basic Applications of Computer Home
Computers are used at homes for several purposes like online bill payment, watching movies or shows at home, home tutoring, social media access, playing games, internet access, etc. They provide communication through electronic mail. They help to avail work from home facility for corporate employees. Computers help the student community to avail online educational support.
Medical Field
Computers are used in hospitals to maintain a database of patients‟ history, diagnosis, X-rays, live monitoring of patients, etc. Surgeons nowadays use robotic surgical devices to perform delicate operations, and conduct surgeries remotely. Virtual reality technologies are also used for training purposes. It also helps to monitor the fetus inside the mother‟s womb.
Entertainment
Computers help to watch movies online, play games online; act as a virtual entertainer in playing games, listening to music, etc. MIDI instruments greatly help people in the entertainment industry in recording music with artificial instruments. Videos can be fed from computers to full screen televisions. Photo editors are available with fabulous features.
Industry
Computers are used to perform several tasks in industries like managing inventory, designing purpose, creating virtual sample products, interior designing, video conferencing, etc. Online marketing has seen a great revolution in its ability to sell various products to inaccessible corners like interior or rural areas. Stock markets have seen phenomenal participation from different levels of people through the use of computers.
Education
Computers are used in education sector through online classes, online examinations, referring e- books, online tutoring, etc. They help in increased use of audio-visual aids in the education field.
Government
In government sectors, computers are used in data processing, maintaining a database of citizens and supporting a paperless environment. The country‟s defense organizations have greatly benefitted from computers in their use for missile development, satellites, rocket launches, etc.
Banking
In the banking sector, computers are used to store details of customers and conduct transactions, such as withdrawal and deposit of money through ATMs. Banks have reduced manual errors and expenses to a great extent through extensive use of computers.
Business
Nowadays, computers are totally integrated into business. The main objective of business is transaction processing, which involves transactions with suppliers, employees or customers. Computers can make these transactions easy and accurate. People can analyze investments, sales, expenses, markets and other aspects of business using computers.
Training
Many organizations use computer-based training to train their employees, to save money and improve performance. Video conferencing through computers allows saving of time and travelling costs by being able to connect people in various locations.
Arts
Computers are extensively used in dance, photography, arts and culture. The fluid movement of dance can be shown live via animation. Photos can be digitized using computers.
Science and Engineering
Computers with high performance are used to stimulate dynamic process in Science and Engineering. Supercomputers have numerous applications in area of Research and Development (R&D). Topographic images can be created through computers. Scientists use computers to plot and analyze data to have a better understanding of earthquakes.
COMPONENTS OF A COMPUTER SYSTEM
The computer system consists of three units: i) Hardware – these are the physical or tangible computer components e.g. Keyboard.
ii) Main Memory (Primary Storage) It is a type of storage that is directly accessible by the processor. Provides storage location for data and instructions accessed by the control unit.
- Holds data awaiting processing -Holds data that has been processed awaiting to be output -Holds data being processed
TYPES OF MEMORY
- ROM (Read Only Memory)
- RAM (Random Access Memory)
- Read Only Memory It is used to store programmed instructions/ data permanently or semi permanently. Data and instructions stored in ROM are those required unchanged for a very long time e.g. booting instructions, computerized fuel pump instructions etc.
Types of ROM a) MROM (Mask Read Only Memory) Once the content is written on it by the manufacturer it cannot be changed. b) PROM (Programmable Read Only Memory ) Allows the user to alter it only once after the content is written on it. c) EPROM (Erasable Programmable Read Only Memory ) The content stored in the memory can be erased by exposing them to ultra violet (UV) light and then reprogrammed for another use. d) EEPROM (Electrically Erasable Programmable Read Only Memory) This type of ROM can be erased and programmed using electricity e.g. memory that stores BIOS.
Characteristics of ROM o Can only be read but cannot be written on it unless it is a special type of ROM o It is non-volatile i.e. its content is not lost when the computer is switched off o Stores permanent or semi permanent instructions from the manufacture.
- Random Access Memory It is also known as working storage. It is called random access memory because its content can be read directly regardless of the sequences in which it is stored. Used to hold instructions and data needed by the currently running application. NB : The content in RAM is held temporarily and therefore, the content is lost once the computer is turned off. Types of RAM a) SRAM (Static Random Access Memory) It is a very fast memory located inside the microprocessor. It is used for special purposes like to enhance the processing speed.
b) DRAM ( Dynamic Random Access Memory) It is relatively slower than SRAM. Holds its content for short time, even when power is on. To maintain its content, it must be refreshed severally.
Characteristics of RAM o Data can be read (retrieved/ opened) & written (stored) in it. o It is volatile (temporary) storage because its content is lost when the power is switched off. o Its content is user defined i.e. the user dictates what is to be contained in RAM.
Special Purpose Memories Apart from ROM and RAM, there are several types of special memories found inside the CPU or found in the input/ output devices. NB: These memories increase the overall performance of the CPU during processing of data & instructions.
These memories include buffers, registers and cache memory.
a) Buffer It is a special purpose memory used to provide temporally storage so that the CPU is set free to carry out other activities instead of waiting for all data to be entered or to be output. For example, a printer cannot work at the speed of the CPU, therefore the printer buffers temporarily holds the output to be printed hence freeing the CPU to perform other functions. NB: Buffers can hold more than one piece of data at a time.
b) Cache memory -It is a supplementary memory system that temporarily stores frequently used instructions and data for quicker processing by the central processing unit (CPU) of a computer It is a very high speed type of SRAM whose purpose is to allow the processor to access data and instructions faster.
c) Registers They are special purpose memories which hold data temporarily before and after processing. Unlike buffers, registers hold one piece of data at time and are inside the CPU. Purpose of registers Used for holding instructions currently being processed. It is a high speed storage location.
Examples of Register i) Accumulator – Temporarily holds the results of the last processing step of ALU. ii) Instruction register - Temporarily holds an instruction just before it is interpreted into a form that CPU can understand it. iii) Address register - Temporarily holds next piece of data waiting to be processed. iv) Storage register - Temporarily holds a piece of data that is on its way to and from the CPU and the main memory
Memory capacities Memory and storage capacity is measured in units called bytes. A byte is equivalent to a single character. A byte is made up of 8 bits. Bit is an acronym standing for BInary digiT. 8 Bits = 1 byte 1 Kilobyte (KB) =1,024 bytes (approximately one thousand bytes) 1 Megabyte (MB) = 1,048,576 bytes (approximately one million bytes) 1 Gigabyte (GB) =1,073,741,824 bytes (approximately one billion bytes) 1 Terabyte = 1,099,511,627,776 bytes (approximately one trillion bytes)
Overall Functional Organisation of the CPU The ALU, CU and the Main Memory are linked through electrical pathways called Computer Buses.
Types of computer buses
i) Control bus It‟s a unidirectional (one-way) bus that carries command signals from the Processor. These signals are necessary to coordinate the activities of the entire system. ii) Address bus It carries the address of the memory location or device to be acted on by the Processor. It is a unidirectional (one-way) bus from the Processor to the external devices. The Address bus is wide (usually between 4 – 32 lines) to enable it to address as many devices as possible. iii) Data bus It is a bi-directional (two-way) bus that carries data & information to and from the Processor. The Data bus usually carries data for processing.
Note. The Data Bus determines the Bus Width of the microprocessor. Its size indicates the moving capability of information of the chip. It consists of 4, 8 or 16 lines each carrying 1-bit at a time.
Data projector
HARD COPY OUTPUT DEVICES
The most common hardcopy output devices include printers, facsimile (fax) and plotters.
SECONDARY (AUXILIARY) STORAGE DEVICES AND MEDIA (BACKING STORAGE) These are devices that complement the primary memory or main memory. They store information for longer period.
Characteristics of secondary storage
- They provide slow access of information.
- They have high data storage capacity.
- The devices are cheap.
- They are non-volatile. Secondary storage units store data permanently.
- Used for mass storage of data & program files not currently being operated on.
- Re-usability - stored data can be erased and the media is re-used to store fresh data
Factors Considered When Choosing a Storage Device i. Cost – The storage devices come in different prices. ii. Availability – Is the desired storage device available in the market? iii. Accessibility to information stored in it, i.e. sequential or direct. iv. Durability – One should buy a device that is long lasting. v. Storage capacity – A device with a large storage capacity will hold more data and information. vi. Physical size and portability – Some device can easily fit in a pocket while others cannot. Small- sized devices are more portable i.e. they can easily be carried from place to place. vii. Compatibility with the existing computer system hardware e.g. a computer should have a CD drive if the device to be used is a compact disk (CD).
Secondary storage include:
Disk drive
- A Disk drive is a computer device for reading or writing data from or into a storage media.
- It can also be described as a unit that houses a disk.
Examples of disk drives ; Hard disk drive (HDD or drive C:). Floppy disk drive (FDD or drive A:). CD-ROM drive. DVD-ROM drive. Tape drive. Zip drive.
The Need for Secondary Storage in Computers.
- The amount of storage needed on a Microcomputer system is greater than the storage space available in the Main memory
- The RAM is volatile hence need to store programs & data in secondary storage devices from which it can be retrieved when needed.
- Primary storage is expensive, thus the need for secondary storage devices which are cheaper.
FUNCTIONS OF SECONDARY STORAGE DEVICES. (i). Used to store backup data & instructions that is not needed immediately by the CPU. (ii). Used for transferring files from one machine to another. (iii). Used to back up files for safe-keeping. (iv). Used to install new software.
CLASSIFICATION OF SECONDARY STORAGE
- Removable storage devices – These devices are not fixed on the computer system unit.
- Fixed storage devices – These devices are housed inside the computer system unit e.g. hard disk.
REMOVABLE STORAGE DEVICES
- Magnetic disk e.g. floppy disks/diskettes, zip disks, jaz disk e.t.c
- Magnetic tapes
- Optical disk e.g. CDs, DVDs, optical tapes e.t.
HANDLING REMOVABLE STORAGE MEDIA The following rules should be observed to avoid loss of data held on removable storage devices: i. Do not expose the storage media to excessive heat to avoid damaging the disk shape, data surface or electronic components. ii. Do not drop a removable media to avoid breakage or damage on its electronic components in case of solid state devices. iii. Do not bend, fold or scratch the surface of optical disks to avoid loss of data due to damaged data surface. iv. Do not forcefully eject a storage media from drive or USB port because this may result to data loss.
CRITERIA FOR SELECTING A COMPUTER SYSTEM
a) Processor speed Good computer must have a high processor speed. It is important to buy a processor that suits ones need not necessarily the fastest. b) Memory capacity A good computer should have sufficient memory. Presence of an extra memory slots for upgrading. c) Warranty It is an agreement between the buyer and the seller that spells out terms and conditions of after selling the product. A good warranty should scope a cover for six months and above, callout response and liability agreement, preventive maintenance. c) Cost It is important to do a market survey before purchasing a computer. d) Upgradeability and compatibility When buying a computer, the best option would be to get one that can be easily be upgraded and compatible across platforms. e) Hardware Portability Smaller devices enhance mobility. g) Special User needs Consider the unique needs of the user and the type of data to be processed. h) Authenticity This refers to genuineness, validity and legitimacy of an item. Make sure the software is an original copy and must be accompanied by certificate of authenticity. i) Documentation It refers to the manual prepared by the developer, this include the installation guide, maintenance and user guide. j) Reliability and security The software should offer good security to confidential and private information from unauthorized access. k) User friendly This is a measure of how easily the user can be able to operate the computer. l) Compatibility and system configuration The software product should be compatible with the existing hardware, operating system or application programs.(Compatibility refers to the ability of the computer to run the software). It is important that one reads the installation guide and system requirements that comes with the
Alphanumeric (Tying) keys – labelled A – Z, Caps lock, Enter keys, Tab key, Spacebar, backspace etc. Cursor movement (Navigation) & Editing keys – arrow keys, Page up and Page down, Home and end keys, Edit keys, Insert key, Delete Special keys – Shift, Ctrl, Alt, Esc etc.
Numeric keys –0 to 9, +, “, /, -
Alt Key A computer key that you press together with another key so that the other key does something different from what it usually does. You can also refer to this key simply as Alt. Backspace The key that you press on a keyboard to move one space backwards in a document. Caps Lock A key on a computer keyboard that makes all the keys produce capital letters. Control Key A key on a computer keyboard that is used in combination with other keys for doing particular operations. This key is usually marked „Ctrl‟. Delete Key A computer key that removes characters. This key is sometimes simply referred to as del. Enter Key A key on a computer keyboard that makes the computer perform an action or start a new line of writing. Escape Key A key on a computer keyboard that allows someone to stop an action, leave a program, or return to a previous menu. This key is usually marked „Esc‟. Num Lock A computer key that you press to make the number keys below it enter numbers and not be used for moving up and down a document.. Return key A key on a computer keyboard that makes the computer perform an action or start a new line of writing. Shift Key The key that you press on a computer keyboard when you want to write a capital letter. Space Bar The long narrow bar at the front of a computer keyboard that you press to make a space between words when you are typing. Tab Computing a button on a computer keyboard or typewriter that you press to move several spaces along the same line.
Touchpad Computing a small flat surface on a laptop computer that you touch with your finger in order to move the cursor on the screen.
List of Common Control Key Shortcuts Ctrl+A These two keys will select all text or other objects. Ctrl+B Bold highlighted text. Ctrl+C Copy any selected text or another object. Ctrl+D Bookmark an open web page or open font window in Microsoft Word. Ctrl+E Center text. Ctrl+F Open find window. Ctrl+G Open Find in a browser and word processors. Ctrl+H Open the Find and Replace in Notepad, Microsoft Word, and WordPad Ctrl+I Italicize text. Ctrl+J View downloads in browsers and set justify alignment in Microsoft Word. Ctrl+K Create a hyperlink for the highlighted text in Microsoft Word and many HTML editors. Ctrl+L Select address bar in a browser or left align text in a word processor. Ctrl+M Indent selected text in word processors and other programs. Ctrl+N Create a new page or document. Ctrl+O Open a file in most programs. Ctrl+P Open a print window to print the page you're viewing. Ctrl+R Reload page in browser or right align text in a word processor. Ctrl+S Save the document or file. Ctrl+T Create a new tab in an Internet browser or adjust tabs in word processors. Ctrl+U Underline selected text. Ctrl+V Paste any text or another object that has been copied. Ctrl+W Close open tab in a browser or close a document in Word. Ctrl+X Cut selected text or another object. Ctrl+Y These keys will redo any undo action Ctrl+End Moves cursor to the end of a document instead of end of the line. Ctrl+Z Pressing these two keys will undo any action. Ctrl+Esc Open the Windows Start Menu. Ctrl+Tab Switch between open tabs in browsers or other tabbed programs.
COMPUTER SOFTWARE
Software : Software is a program or set of instructions that causes the Hardware to function in a desired way. The basic difference between the Hardware and Software is just the same as that exists between TV and TV studio. Without TV studio (software) from where the programs are telecast, the TV (Hardware) is a dead machine.
Types of Software
- System software
- Application software
System Software Operating system/system software : this software defines the functions of a computer. They are designed specifically to coordinate the functions of the hardware, make hardware accessible to one another and grant application software access to needed hardware. There are three major operating systems today for computers, Windows Operating System, Mac Operating System and Linus Operating System. Each one of these has its own versions (history). For mobile devices, the list is more elaborate but the most common ones are iOS (iPad and iphone operating system), Android,
