COMPUTER STUDY

COMPUTER APPRECIATION

HISTORY AND DEVELOPMENT OF COMPUTER

Computer can be defined as an electronic device that accepts input, processing, outputs and store data and information. The computer accomplishes all of these by obeying a sequence of instructions called a program.

Or

Computer could be defined as an electronic device, capable of receiving data, processing and producing data or information.

COMPUTER EVOLUTION: By evolution we mean a gradual development process that precedes an invention. The evolution of computer is as a result of man’s desire to resolve her mathematical problems.

Man had a problem with mathematics, accounts, bills, record keeping and data processing etc.

The very first calculation machine that was devised by man for mathematical solution was the ABACUS which was invented in about 34BC, it was a machine pebble counter in which beads were strung on wires or string held in a frame.

After the Abacus came several machines like the slide rule, which was invented by John Napier in 1914, and the DIGITAL CALCULATION invented by Blasie developed in 1642 has been in use. In 1804 a French man named Joseph Jacquard development a PUNCH CARD SYSTEM for controlling the threads on his weaving looms.

Charles Babbage followed up in 1833 analytical engine which could perform calculations automatically using in punch cards. This machine was like because it had input output and other units that characterized contemporary computer.

The first computer was founded by Presper Echert and John Mauchly of IBM (International Business Machines) under the auspices of Holleritn. (The father of IBM).

GENERATION OF COMPUTERS

The operating system has undergone a lot of a modifications and refinements since its incepting. Generations of operating systems range from zero generation to fifth generations.

Zero Generation: In the 40s and early 50s, computers were made used without any Operating System.

Programming was made possible by coding programs and instruction to be computer in machine language (Binary codes) or assembly codes.  

1^st Generation: A major problem associated with the early first generation electronic computers were reliability and storage of data and information. Vacuum tubes were used for computing and storage.

2^nd Generation:   The development of transistors in the late 1940’s gave birth to the second generation of computers. These machines used transistors for their internal circuitry. Transistors were solid state devices which were small, very fast, and much more reliable that vacuum tubes.

3^rd Generation: The development of IC’s quickly gave rise to medium-scale-integrated (MSI) circuits containing hundreds of transistors. Third generation computers were built using MSI circuit.

4^th Generation: Development in the miniaturization process of integrated circuits made it possible for Large-Scale-Integrated (LSI) and Very-Large-Scale-Integrated (VLSI) circuit to be produced and be used for the fourth generation computers.

5^th Generation: The fifth generation computers appear to be the brainchild of the Japanese. They have pursued the idea of having an intelligent computer system, which will be implemented with VLSI chips and Expert systems.

This generation of computers is expected to contain programs that are mimic human intelligence.

Various fifth generation products, such as programs that translate text from one language to another and computers that could be directly controlled by speech have been appearing in the market since the 1990’s.  

CHARACTERISTICS OF COMPUTER:

Computers have the following characteristics. KILOBYTE, MEGABYTE, GIGABYTE & TERABYTE are multiples of bytes in thousands, millions, and trillion respectively. Bytes define the memory space of a character in computing terms. In accordance with ASC II code, define combinations of 8 0s and 1s equals a specified alphanumeric character (8 bits = 1 bytes)

1.     Electronic: - Computer functions through the action/emission of electrons and are hence similar to our common household electronic gadgets.

2.     Speed: - Computer has the characteristic of being very fast, most computers process information in 1 million of a second. So a task that would ordinarily take a Human being a long time to accomplish can be easily achieved by the computer in far less time.

3.     Device: - A computer is a device. It is a tool used by humans to make their work easier and the accomplishing time quicker.

4.     Storage: - Computer has the capacity to store data and information for future reference and retrieval.

5.     Versa tic: - Computers have the characteristic of being able to be applied to diverse applications. For instance, computer can be used in typing letters, playing games designing house etc.

6. Diligence: - Like all tools, computers are very diligent in carry out tasks.

LIMITATIONS OF COMPUTER:

Computer with all their power and incredible speed also have limitations.

These limitations are:

1.     Computer lack initiative. Computers cannot by themselves decide to act in a way different from how they have been programmed.

2.     Computer cannot react to unforeseen and therefore un-programmed events. Computer cannot simply think for their selves. A computer can only act upon a set of instruction given to it and nothing more.

COMPONENTS OF THE COMPUTER SYSTEM:

The computer system has three basic components. These are:

1.     Human ware / People ware

2.     Hard ware

3.     Soft ware

Human ware/People Ware: The human ware component simply refers to the computer user. Those that use a computer for work or play are described as human ware.

Hard ware:-  The hard ware implies or is used to describe all physically tangible and visible parts of computer system. In other words, all parts of a computer that can be seen and touched are called the hardware.

Software: - Software is sequences are instructions directing the computer on what to do at any particular circumstance. Software can simply be thought of as the non-physical parts of the computer system.

Or

An instruction or command given to a computer to perform a particular task or function. This instruction or command comes in form of programs that one runs in a computer to enable you work perfectly. There are basically two types of software: the Operating system software and Application system software.

SOFTWARE COMPONENTS OF A COMPUTER

Introduction

Computer software is the collective term for all programs which control the activities of a computer. A program is basically a sequence of instruction that is given to a computer to guide it in processing information.

Two categories of programs can be identified. These are SYSTEMS programs (Systems Software) and APPLICATIONS program (Application Software)

SYSTEM SOFTWARE

System programs are programs usually but not necessarily furnished by a computer manufacturer which contribute to the proper control and enhanced performance of the computer system. Examples of systems software include Operating Systems (OS), Utilities, Translator, and Editors.

Utilities and translators – These are extra software installed to make the operating system perform more functions such as repairing spoiled disk or translating programming language into machine language.

OPERATING SYSTEMS

Operating Systems (OS) are formed by a suite of programs which takes control over the operations of the computer to the extent of being able to allow a number of programs to be run on the computer to the computer without human intervention.

Some of the functions of operating system include, allowing users to share data amongst themselves, scheduling and loading of programs to provide for continuous processing, control over selection and operation of Input/output (I/O) devices, loading of programs and subroutines into primary memory as and when required, allocation of memory to programs and data files, passing of control from one job (program) to another under a system of priority, provision of error-correcting routine, and the provision of interface between the computer and users thereby facilitating communication with the computer operators and others users via terminals. 

APPLICATION SOFTWARE – These are software designed to perform specific tasks in particular areas of human endeavor. Application software are written to solve practical problems such as inventory control, payroll system, word – processing, spreadsheet analysis etc. examples of application software are CORELDRAW, AUTOCARD, MS ACCESS, MS EXCEL, MS – WORD etc.

DIFFERENCE BETWEEN WINDOWS AND MS – DOS

1)         Windows operating system is very interactive and friendlier to users than MS – DOS.

2)         Windows operating system is multi-tasking operating system i.e. it has the ability to run more than one program at a time while MS-DOS is unit-tasking operating system. That is, it can only run one program at a time.

3)         Windows operating system uses of graphical user interface (GUI), which allows you to get up and running through the use of pictures and graphics where as MS-DOS uses textual user interface (TU).

4)         Windows operating system uses both mouse and keyboard to choose commands. While MS-DOS is keyboard oriented only.

5)         Windows also incorporate hyper link and wed function into the desktop. These are not applicable in MS – DOS environment.

FUNCTIONS OF AN OPERATING SYSTEM

·        Communicating with computer operator by means of console

·        Loading and unloading of programs

·        Supervising multi-programming operations

·        Allocating peripherals to programs and checking their availability.

·        Controlling and monitoring all information transfer

·        Warning the operator when peripheral units require attention.

CLASSIFICATION OF COMPUTERS:

Computer can be classified into the following:

1.     Analog (analogue) computers: - This type of computer measures physical magnitudes such as temperature and signals whose amplitude varies with time. Generally, analog computers are used for scientific and engineering purposes.

2.     Digital Computers: - These are computers that process discrete signals such as alphabets, numbers and punctuation keys.

3.     Hybrid computers: - The hybrid computers can process both discrete and continuous signals.

CLASSIFICATION BY PURPOSE

General Purpose computers: - This category of computers can be used for several human applications. They can be used in typing letters, calculating payrolls, designing card etc.

Special Purpose computers:-These, as the name suggests, are computer designed for a particular job only and used to solve problems of a restricted nature. Examples are computers designed for air traffic control or weapons guidance systems.

CLASSIFICATION BY SIZE

(a)              Supercomputer: These are the fastest, largest and most expensive computers in the world. Supercomputers are common only in Europe and America. They have the capacity to perform one billion operations in one second.

(b)     Mainframes: - These are large computer having wide range of   memory facilities.

(c)      Minicomputer: - These are middle-range computers, between the   smallest (Micro) computers and biggest (Mainframe) computer.

(d)     Microcomputer: - These are computer realized on a small number of silicon clips with a microprocessor as the Central Processing Unit (CPU).

They are usually the smallest in size, in term of memory (data storage facility) capacity. This is the software required by any computer to start and communicate with user and application software. Examples are: windows XP 2005, 1998, 2000, NT, MS DOS, etc.

                   THE FOUR MAJOR PROCESSES OF A COMPUTER ARE:

a)     Input Unit

b)    Processing Unit

c)     Output Unit

d)    Storage Unit

INPUT UNIT: Input consists of devices and mechanism through which information is fed into the computer system. Examples of devices in the category include:

a)     Keyboard

b)    Mouse

c)     Joystick

d)    Scanner

e)     Light Pen

Keyboard:-

Keyboard is an input device as well as a control device. I.e. it is used to give a command to the computer. The keyboard is the most common computer input device. The keyboard consists of 104 keys, which are divided into 5 groups of keys:

                   I.      Alphabet keys: this area of the keyboard is much the same as that on a standard typewriter. The typing keys comprise all alphabets, numerals, punctuation keys such as the SHIFT KEY, CAPLOCK KEY.

                II.      Special keys: These keys have particular functions ascribed to them. These keys include: ESC, (Escape key), CTRL (control key), ALT (Alternate key), BACKSPACE, HOME, END, INS (INSERT), DEL (DELETE), PGUP (PAGE UP), PGDN (PAGE DOWN), etc.

             III.      Function keys: These are labeled F1 to F10 for Enhanced keyboards while standard keyboards have function keys labeled F1 to F12. These keys have various functions depending on the software in it. Example are: alpha numeric keys: - A-Z, 1-10) numeric function keys: keys keypad: - it usually found at the right side of the keyboard. Editor/cursor keys.

            IV.      Cursor Movement keys: These are made up of 4 directional keys pointing up, down, left and right. They are used to position the cursor on the screen. The cursor indicates the location on which a character typed would appear.

               V.      Numeric keypad: The numeric keypad consists of numeric keys placed together with the arithmetic operator symbols.

Ø These keys when pressed executes functions/commands depending on the software that is in use;

Ø Some of these keys are permanently labeled with the functions they execute while others are numbered and perform different functions on different software.

Ø Usually each soft ware product comes with own keyboard template which shows the functions/commands assigned to each function keys for easy e.g. Most software packages have F1 as the function  keys for help.

Ø It also contains number keypad and cursor control keys for easy data entry. The cursor control keys are used to move the cursor around the screen or to select options in menus and submenus and to view part of documents that are not appearing on the screen by scrolling up and down.

o   Summering, there are three basic ways a command can be entered through the keyboard:

ü Key in the command using the alphanumeric portion of the keyboard.

ü Press a function key.

ü Use the cursor control keys (arrow keys) to select a menu option from a menu.

The keyboard consists of three main divisions which help to differentiate their functions. The three divisions are:-

·        The functions keys: this is set of twelve keys (12) from F1 – F12 for standard keyboard while Enhanced keyboards have ten (10) F1 – F10 on the top most line of the keyboard.

·        Alpha – Numeric keys: The right division of keys that switched functions from numbers to cursor control

·        Alphabet keys: These are keys normally used for documentation.

Mouse – The mouse is a peripheral pointing device used to make selection of commands. It can perform functions like select menu commands, move icons, resize windows, start programs, and choose options.

Left Mouse Button

Right Mouse Button

Figure 1:

MOUSE ACTION:

There are four common mouse actions:

Ø    CLICK: A click often selects an item on the screen. To click press and release the left mouse button

Ø    DOUBLE – CLICK: A double-click often opens a document or start a

Program. To double-click, quickly press and release the left mouse button twice.

Ø    DRAG AND DROP: Dragging and dropping makes it easy to move an item on the screen, position the pointer over an item on the screen and then press and hold down the left mouse button. Still holding down the button move the pointer to where you want to place the item and then release the button.

Ø    RIGHT – CLICK: A right click often displays a list of commands on the screen. To right – click, press and release the right mouse button.   

Joystick: - A Joystick is a pointer device. It is basically a lever that movement in all directions and controls the movement of a pointer. Joystick is used mostly for computer games.

The Light Pen: - A light pen is similar to a mouse except that with a light pen you can move the pointer and select objects on the display by directly pointing to the object with the pen.

Scanner: - used to input document into the computer.

[

PROCESSING UNIT- The processing unit is central to the operation of the computer. The processing unit can be referred to as the actual computer, for without this section the computer remains just a mere electronic device like our television set.

The processing unit comprises components such as:

a)     The CPU

b)    Power Supply Unit

c)     Hard disk

d)    Mother Board etc.

e)     Processor

f)      Memory (RAM)

g)     Case (chassis)

STORAGE UNIT: - This consists of devices by which computer stores information for further reference retrieval.

The memory system of a computer is made up of the Primary Memory and Secondary Memory. For a PC, the primary Memory is mainly made up Ram (Random Access Memory and a small ROM (Read Only Memory).

1.       PRIMARY STORAGE:        The primary memory contains the programs and

data being processed at any given time. It is smaller in size than the secondary memory. It is however much faster than the secondary memory. 

(a)     ROM- The contents of ROM are usually loaded in at the time of manufacture. It is an area of the main memory where data and information that can only be read but cannot be altered, deleted or written into. The contents of ROM are not lost when power or the computer system is switched off.

(b)             RAM – This part of the main memory contains data, which can be read,

altered, deleted and written into. Unlike ROM, RAM is unpredictable and hence can only store data and information temporarily. Being unpredictable here means that when there is power cut all data and information stored in RAM are lost.

2.       SECONDARY STORAGE:  The secondary storage is also sometimes

called the auxiliary storage or Backup Memory or storage. Is a

supplement of primary memory? It usually holds programs and data files for

both processed and unprocessed information and would have slower but larger

capacity storage when compared with primary memory.  

RAM (Random Access Memory):- Memory comes in several forms, but generally the processor accesses random access memory (RAM). RAM gets its name from how the memory is physically accessed. Data can be accessed by one of two methods, either sequentially or randomly. RAM allows your computer to store and retrieve data in random locations in memory.

OUTPUT UNIT: - Output unit transforms processed information from its internal form into ordinary readable forms. The most common output devices are:

1).     Monitor     

2).     Printer

3).     Plotter        

4).     Line printer:

This category of printers makes use of a continuous bank, containing all the

Characters which revolve at high speed in front of a ribbon. 

While the monitor provides temporary display of the output, printer and plotter provide permanent output called hard copy.

1).     MONITORS: The monitor is similar to the television. A Monitor is sometimes called screen or Visual display units (VDU) monitors are either monochrome or color. Monochrome monitors display output in a single color only.

While on the other hand colored monitors can display a Variety of colors.

Monochrome monitors have become outdated making colored monitors the most common.

2).     PRINTERS: Printers produce output on paper. Printers can be classified on whether they print a character, a line or a page at a time. Character printers print a single printer on the other hand print a line at a time.

3).     PLOTTERS: Plotters produce lines and curves move distinctively than printers. It is for this reason they are used mainly by engineers and architects for producing design or engineering plans.

DATA AND INFORMATION

Data: Data is unprocessed information or a raw material.

Information: Information is a processed data.

Information can be presented in two ways:

a)     Soft copy: These are information that can be only be view but cannot be touched.

b)    Hard copy: Hard copies are information on paper or on things we can see or touched.

DATE PROCESSING AND ITS APPLICATION

INTRODUCTION: - Data Processing is a critical component of business organizations. It is a process of manipulating specific operations on a set of data or a database. Various methods, approaches, and services are employed in the processing of data.

1.       Information is a collection of facts organized in such a way that it has more value beyond the facts themselves.

          The collections of data, rules, procedures, and relationship that must be

          followed are contained in the knowledge base.

         

Data Processing:

Data processing refers to the process of performing specific operations on a set of data or a database.