Lecture 1

MIS & Computer Application

Fall 2010 Lectures - MBA02093

Instructor: Khurram Khan

Notes Written by: Ali Arshad17-Nov-2010

2 Fall 2010 Lectures - MBA02093

Lecture 1Lecture 1 consists of basics about computers. It will contain knowledge like definitions, examples and information. Let’s start by the definition of computer.

1. Computer: An electronic device that receives data, processes data, stores data, and produces a result (output).Computers are made of 2 main parts – hardware and software.

2. Hardware: the tangible, physical equipment that can be seen and touched such as: Computer case, Monitor, Keyboard & Mouse, Speakers etc...

3. Software: the intangible set of instructions that tell the computer what to do, like programs, software programs or operating system.

4. Data vs. Information: data refers to symbols that represent facts or ideas... they really don’t mean anything until they are processed, or put in some sort of context. Then they become information... so data is raw and information is processed.

5. Program vs. Software: 5.1. A program is a set of instructions written in a programming language to perform a particular

function. Many programs combine together to form software;

5.2. Software refers to a collection of several programs, other procedures and documentation. Software is also used to perform a task. The most common programming language used for making software is C and C++. Software is of two types that is system software which is the operating system and application software. So a program is a set of instructions for performing a task whereas software is made up of several computer programs. Traditionally software is purchased on a CD or DVD or is downloaded from the internet; in either case, the software needs to be installed on a computer before it can be used. There are two type of software. System software and application software.

6. Types of software:

6.1. Application software -- includes the everyday programs that you use such as Word Processors, Spreadsheets and Databases. Application software run under System Software, and are made to do a specific task i.e. (Word Processing etc), which have indirect access to the hardware (i.e. Behind System Software). There are two types of Application software: General software and Custom software.

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Fall 2010 Lectures - MBA02093 3

6.1.1. General software are simply off the shelf (which may also include free software) computer software or hardware, technology, or computer products, which are ready-made and available for sale, lease, or license to the general public.

6.1.2. Custom software (also known as bespoke or proprietary software) is a type of software that is developed either for a specific organization or function that differs from or is opposite of other already available software e.g. off-the-shelf software. It is generally not targeted to the mass market, but usually created for companies, business entities, and organizations. Custom software also refers to when companies or governments pay for customized software for budget or project managing. This software is not targeted for mass market.

6.2. System Software -- has direct control and access to our computer hardware, and memory locations. They perform I/O (On/Off) operations on various memory locations, and control the hardware, to make the application software do a task. Operating systems (OS) are the main examples for system software. Other examples include Programming Languages, Device Driver Software. Etc…

7. Device Driver: (system software) is a program that lets the operating system communicate with the computer hardware. Computer parts need a driver because they do not use standard commands. (Ex.: ATI and Nvidia graphic cards do the same jobs, but not the same way). Many parts need drivers like graphic cards, modem, network card, sound card, computer printer etc… Some other parts do not need drivers because they use a kind of standard. The operating system recognizes those parts and knows how to use those parts. Those include drivers, CD and DVD, Keyboard etc…

8. OS: (Operating system) is System software that allows applications software to communicate with the hardware. It is a link between Hardware and a user, hardware and hardware, hardware and software, software and software. In modern era, a computer is useless without an OS. There are two types of OS: Single Tasking OS and Multi-Tasking OS.

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Figure 1: Link between OS and a user

8.1. DOS: (Disk Operating System) is Single taking OS which was the first widely-installed operating system for personal computers. DOS was (and still is) a non-graphical line-oriented command- or menu-driven operating system, with a relatively simple interface but not overly "friendly" user interface. Its prompt to enter a command looks like this: " C :>”. The first Microsoft Windows operating system was really an application that ran on top of the MS-DOS operating system. Today, Windows operating systems continue to support DOS (or a DOS-like user interface) for special purposes by emulating the operating system.

8.2. Windows: Windows is a series of software operating systems and graphical user interfaces. It is a Multi-Tasking OS. For example, in the most popular OS, Microsoft Windows, it's entirely possible for a Windows user to be writing a note in a word processor while downloading a file from the Internet while printing the text of an e-mail message.

9. As we learned in 5.1, a set of instructions that tell a computer what to do is called a program. Further we discussed in 6.2 that programming languages are a type of system software. Computer programs are written in programming languages. A person who develops a program is called programmer. The programmer develops programs to instruct the computer how to process data to convert into information. A programmer uses programming languages or tools to write programs. Let’s discuss about programming languages.

10. Programming Languages: A language is a means of communication. We communicate our ideas and emotions using natural languages like Urdu, English etc. Similarly, a computer language is a means of communication between a user and the computer. A set of words, symbols and codes used to write programs is called programming language. Different programming languages are available for writing different types of programs. Some languages are specifically used for writing business programs, other are used for writing scientific programs etc. with the help of computer language, a programmer tells a computer what to do. There are two types of computer programming languages: Low-Level Languages and High-Level Languages.

10.1. Low-Level Languages: These languages are near to computer hardware and far from human languages computer can understand these languages easily. Writing a program in low-level language requires a deep knowledge of the internal structure of computer hardware. Following are the examples of low level languages:

10.1.1. Machine language: A type of language in which instructions are written in binary from is called machine language. It is the only language that is directly understood by the computer. It is the fundamental language of the computer. Program written in machine language can be executed very fast by the computer. Programs written in machine

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language are machine-dependant. Every computer has its own machine language. Machine language is difficult to understand. Writing and modifying program in machine language takes a lot of time. Machine language is also known as first generation language.

10.1.2. Assembly Language: Assembly language is a low level language. It is one step higher than machine language. In assembly language, symbols are used instead of binary code. These symbols are called mnemonics. For example Sub instruction is used to subtract two numbers. Assemble language is also called symbolic language. Programs written in assemble language are easier to write and modify than machine language. Assemble language is mostly used for writing system software. Assemble language is also known as second generation language.

10.2. High-Level Languages: A type of language that is close to human languages is called high level language. High level languages are easy to understand. Instructions of these programs are written in English like words such as input and print. A program written in high-level language is easy to write and modify. High-level languages are further divided into following categories: Procedural languages, object-oriented languages and database query languages.

10.2.1. Procedural Languages: Procedural languages are also known as third generation languages or 3GL. In these languages, a program is predefined set of instructions. Computer executes these instructions in the same sequence in which these instructions are written. Each instruction in this language tells the computer what to do and how to do.

A. FORTAN: FORTAN stands for FORmula TRANslation. It is mainly used for engineering application and scientific use.

B. BASIC: BASIC stands for Beginner All Purpose Symbolic Instruction Code. It was created in the late 1960’s. It was used mainly by students to use the computer for solving simple problems. It is easy to understand. It is widely used for education purpose.

C. PASCAL: This language is used for both scientific and business applications. Its name was assigned in the honor of French mathematician Pascal.

D. C: C language is a popular high level language. It was developed by Dennis Richie at AT&T Bell Laboratories in 1972. It was written as part or UNIX operating system. It is also known as middle-level language because it provides the facilities to write application software as well as system software.

10.2.2. Object-Oriented Languages: OOP is a technique in which programs are written on the basis of objects. An object is a collection of data and functions. Object may represent a

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person thing or place in real world. In OOP, data and all possible functions on data are grouped together. Object oriented programs are easier to learn and modify. C++ and Java are two most popular object-oriented languages. OOP is based on real word modeling. As in real world; things have properties and working capabilities. Similarly, objects have data and functions. Data represents properties and functions represent working of objects. A person can be an example of an object. It has some properties or characteristics that describe what it is. Some properties of person object can be as follows: • Name • Age • Height… The person object also has some functions that

describe what it can do. Some functions of person object can be as follows: • Walk or

Talk • Eat.

10.2.3. Database Query Languages: database is a collection of related data in an organized way. Database query languages are used to retrieve, insert, update, delete or search data from databases. These are non-procedural languages. Non-procedural languages are also known as fourth generation languages or 4GL. In non-procedural languages, user only needs to tell the computer what to do, not how to do. Most popular database query language is SQL (Structured Query Language).

11. Language Processors/Translators: Computer understands only machine language. A program written in high-level or assemble language cannot be run on a computer directly. It must be converted into machine language before execution. Language processor or translator is software that converts these programs into machine language. Every computer has its own translators. Different types of language processors are: • Compilers • Interpreters.

11.1. Compilers: A compiler is a program that converts the instruction of a high-level language into machine language as a whole. A program written in high-level language is called source program. The program converts source program in machine code called object program. The object program can be executed many times. The compiler checks each statement in the source program and generates machine instructions. Compiler also checks syntax errors in the program (We will discuss syntax errors in next point). A source program containing an error cannot be compiled. A compiler can translate the programs of only that language for which it is written for. For example, C compiler can translate only those programs that are written in C language. In a sentence, Compiler spends some time evaluating the entire program and then translates all the programming statements of a program into a machine language program, which is then executed at once.

11.2. Interpreter: An Interpreter is a program that converts one statement of a program into machine at one time. It executes this statement before translating the next statement of the source program. If there is an error in the statements, the interpreter stops working and displays an error message. The advantage of interpreters over compilers is that an error is found immediately. So the programmer can correct errors during program development. The disadvantage of interpreter is that it is not very efficient. The interpreter does not produce an object program. It must convert

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the program each time it is executed. Visual Basic uses interpreter. In a sentence, Interpreter translates interactively each programming statement into an immediately usable machine language instruction. Although an interpreter slows down the execution speed of a program somewhat, it does not require extra steps to compile and link like a compiler.

Figure 2: Difference between Compiler and Interpreter

12. Programming Errors: When a program is not written correctly, it gives an error. An error can disrupt program flow, create nonsensical results or cause a program to terminate completely. Understanding the differences between syntax errors and logical ones helps the debugging process by making error location a simpler task. Neither type of error is confined to programming. Let’s learn about these errors.

12.1. Syntax Errors: Syntax Error occurs when the code isn't formatted or typed correctly i.e. in Python (a programming language), typing “If” instead of “if” gives an error because it only recognizes lowercase. So we can also say that syntax errors are errors in spelling and grammar. As a result the code fails to compile (Error message from compiler). We can use the compiler or interpreter to uncover syntax errors but we must have a good working knowledge of error messages to discover the cause of the error.

12.2. Logical Errors: Logical Error occurs when there is a fallacy of reasoning i.e. in Python (a programming language), typing “if x < 0” and “x > 5”. Since a value can't be less than 0 and greater than 5, a logical error will occur. So we can say that these are the errors that indicate the logic used when coding the program which failed to solve the problem. We do not get error messages with logic errors. Our only clue to the existence of logic errors is the production of wrong solutions. The main difference between Syntax and logical error is; when there is a syntax

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error, the program will crash. But when there is logical error the program will not crash but will give unexpected output. For Example: A syntax error means that a language was used incorrectly, if you forget to put certain symbols in source code, the machine will not be able to read it. A logic error means though the language was used correctly, there was a misunderstanding: if you want a, where (b= c + a) and you give a = b-a instead of a = b-c, then you will get the wrong answer, but have used the correct language.

12.3. Runtime Errors: A runtime error is a computer error that appears in the form of a message box consisting of a particular code along with its corresponding definitions. Usually, a user will notice that the computer becomes noticeably slow before a runtime error appears. Runtime Error occurs at run-time. Such errors cause a program to end unexpectedly or even cause system shut-down. Such errors are hard to detect. For example error caused due to low system memory or something divided by zero, 44/0. Runtime errors indicate bugs in the program or problems that the designers had anticipated but could do nothing about. For example, running out of memory will often cause a runtime error. The runtime or run-time error message can also be caused by: Confliction with TSR (Terminate & stay resident) or other running program, Software issue, Computer Virus, Memory issue etc.

13. Debugger: Even the most experienced software programmers usually don't get it right on their first try. Certain errors, often called bugs, can occur in programs, causing them to not function as the programmer expected. Sometimes these errors are easy to fix, while some bugs are very difficult to trace. This is especially true for large programs that consist of several thousand lines of code. Fortunately, there are programs called debuggers that help software developers find and eliminate bugs while they are writing programs. A debugger tells the programmer what types of errors it finds and often marks the exact lines of code where the bugs are found. Debuggers also allow programmers to run a program step by step so that they can determine exactly when and why a program crashes. Advanced debuggers provide detailed information about threads and memory being used by the program during each step of execution. In few words, debugger is a special program used to find errors (bugs) in other programs. A debugger allows a programmer to stop a program at any point and examine and change the values of variables.

14. Printer: A printer is an output device that prints characters, symbols and graphics on paper. The printed output is called hard copy. Print resolution is commonly measured in Dots Per Inch (DPI). Different categories of printers are as follows:

14.1. Impact Printers: An impact printer works like a typewriter. It prints characters or images by striking a print hammer or wheel against an inked ribbon. Dot matrix, Daisy wheel and line printers are examples of impact printers. Let us discuss them in little detail.

14.1.1. Dot Matrix Printer: A Dot Matrix printer is am impact printer. It produces printed image when tiny pins on a print head strike an inked ribbon. When the ribbon presses against the paper, it creates dots that form characters and graphics. The print head on a dot matrix printer can contain nine to twenty-four pins. This number of pins depends on

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the manufacture and the printer model. A higher number of pins print more dots that produce higher quality. Overall dot matrix printers do not provide high quality output. They produce a lot of noise while printing. The printing cost of these printers is extremely cheap.

Figure 3: How Dot Matrix Printer prints

14.1.2. Daisy Wheel Printer: Daisy wheel printer is similar to a typewriter. It uses a print wheel. The print wheel is called Daisy Wheel. Each petal of daisy wheel contains character. A motor rotates the wheel. A hammer strikes a petal against the ribbon when the desired character reaches the position on the paper. This prints the character on the paper. Daisy wheel printer is slower then dot matrix printer but better in quality.

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Figure 4: Daisy Wheel

14.1.3. Line Printer: Line printer is a fast impact printer. It prints an entire line at a time. Its speed is measured in Lines Per Minute (LPM). Many line printers can print 3000 lines per minute. Two types of line printers are Band Printers and Chain Printer. It is normally used by mainframe and microcomputers.

Figure 5: Green Bar Paper

14.2. Non-impact Printers: A Non-Impact Printer prints character and graphics on a piece of paper without striking the paper. Some of these use spray ink while others use heat and pressure to create images. These printers are faster than impact printers. Inkjet, thermal and Laser printers are the examples of non-impact printers.

14.2.1. Laser Printer: Laser printers are non-impact printers. Its working is similar to a photocopying machine. The laser printer creates image on the paper by laser beam. LASER stands for Light Amplification by Stimulated Emission of Radiation. Laser throws magnetic material powder on paper in the form of microscopic dots. The density of these dots ranges from 300 to 2000 Dots Per Inch (DPI). The printing speed of laser printers is from 5 to 300 Pages Per Minute (PPM). Laser printers are also called Page Printers. They print complete page at a time. Laser printers produce very high quality print. They are faster than inkjet and dot matrix printers. Color printing with laser printer is very costly. Laser printers are mostly used in business fields.

14.2.2. Inkjet Printer: An Inkjet printer is a type of non-impact printer. It prints characters and graphics by spraying tiny drops of liquid ink on paper. These printers can produce quality text and graphics in both black-and-white and color. Inkjet printers are slower than laser printers. They can print 1 to 6 pages per minute. Its print quality is higher than dot matrix printer. They are also relatively inexpensive. Most inkjet printers have usually two print

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cartridges: one containing black ink and the other containing color. Another type of inkjet is also known as Bubble Jet Printer.

14.2.3. Thermal Printer: Thermal printer is a printer that uses heat process to transfer colored dyes or inks to the paper. Thermal printer is the best color printer currently available but it is also very expensive. It was originally used only in scientific labs to record data. Now this printer is widely used to produce very high-quality color artwork and text. Professional applications requiring very high image quality such as photo studio, medical labs and security identification systems use thermal printers. The cost of this printer is thousands of dollars and it prints images in wide ranges or sizes.

15. Monitor: Monitor is the most common output device. The output displayed by monitor is called Soft Copy. A monitor looks like a television and displays text and graphics. A monitor is also known as CRT (Cathode Ray Tube), display screen or simply screen. Different display screens are distinguished on the basis of following Features.

15.1. Size: Monitors are available in different sizes. The standard monitor for personal computer is 15 to 19 inches. The size of monitor is measured diagonally.

15.2. Color: The display screens can be either Monochrome or Color. The color display screens display output in multiple colors. The color display screens are also called RGB monitors. The number of colors a monitor can display is called Color Depth or Bit Depth. The RGB display screens can create 256 colors and thousand of variations of these colors. RGB stands for Red, Green and Blue. The Monochrome display screens display output in single color. Monochrome display screens show images in a color usually White, Green, Blue, Red or Amber. However, monochrome monitor can display different shades of one color. The number of shades of one color that the monitor can display is referred to Gray-Scale.

15.3. Resolution: All characters and images on the display screen are made of pixels or dots. Pixels are the dots or pictures or picture elements that form images on the monitor. In other words, Pixel is the smallest unit of an image, basically a single dot on the screen. Resolution of a monitor is the number of pixels on the screen. It is the image sharpness of a display screen. High number of pixel means sharper image. Common resolution size is 1024x768.

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Figure 6: The CRT electron gun “shoots” 3 electrons at the screen representing the amount of RGB for the pixel

15.4. Video Display Adapters: A display screen must have a video display adapter attached with the computer to display graphics. It is also called video graphic card. It is a circuit board that determines the following things: • Resolution • Number of Colors • Speed with which images

appear on the display screen.

15.5. Refresh Rate: The refresh rate is the speed with which a monitor redraws the image on the screen. It is also known as vertical scan rate or Vertical Frequency. It is measured in Hertz. It indicates the number of times the screen is refreshed in one second. Refresh is necessary because the phosphors hold their glow for fraction of second. The image on the screen appears more solid if it refreshes rate is high. The screen will flicker less. The refresh rate should be at least 72Hz. Common monitors have refresh rates between 75 and 85Hz.

15.6. Dot Pitch: The distance between each pixel on monitor is called Dot Pitch. It is also called Pixel Pitch. The distance between pixels is measured in Millimeters. Many monitors have a dot pitch of 26 or 28. A smaller dot pitch means that there is less blank space between pixels. A smaller dot pitch results in better and sharper image.

16. Types of Display Screens: Display screens are of two types. These are as follows:

16.1. CRT Monitor: CRT monitor is the most common form of display screen. It looks like a television. It can display text and graphics. It uses Cathode Ray Tube (CRT). CRT tube creates an image on the screen by an electronic beam. CRT consists of one or more guns that fire a beam, of electronics inside the screen. The screen is coated with very tiny phosphor dots from inside. The beam of electronic repeatedly falls on the surface of screen. Every beam-fall takes only a fraction of a second. CRT in color monitors consist of three guns. These guns generate Red,

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Green and Blue (RGB) colors. The other colors are generated with the combination of these three colors. A small example is already shown in figure 6. A Monochrome Monitor is a type of CRT computer display which was very common in the early days of computing, from the 1960s through the 1980s, before color monitors became popular. Unlike color monitors, which display text and graphics in multiple colors through the use of alternating-intensity red, green, and blue phosphors, monochrome monitors have only one color of phosphor (mono means "one", and chrome means "color"). All text and graphics are displayed in that color. Some monitors have the ability to vary the brightness of individual pixels, thereby creating the illusion of depth and color, exactly like a black-and-white television. One of the drawbacks of the monochrome monitor is the potential for what is known as screen burn. This phenomenon is caused by the relatively high intensity generated by the single phosphor. When text is left displayed for long periods of time, it can actually leave an impression on the screen even after the user moves on to view other stored data. Because the pixels that make up the display on a color monitor are composed of multiple phosphors, the potential for screen burn with contemporary monitors is greatly reduced, especially with the use of automatic screen savers and it was the reason why screen savers were made

.

16.2. Flat Panel Monitors: Laptop PCs use flat panel monitors. These monitors take less space. Flat panel monitors use variety of technologies. The most common technology is LCD (Liquid Crystal Display). LCD monitors use much less power than CRT monitor. These monitors are available in different sizes as 15”, 17”, 18”, 21” and 23”. LCD monitors creates images with a special type of liquid crystal that is normally transparent but becomes solid when charged with electricity. LCD monitors are Passive Matrix or Active Matrix. In active matrix display, each pixel on screen is controlled by its own transistor. It is also called Thin Film Transistor (TFT) Monitor. It is much brighter and sharper than passive screens. It is more complicated and more expensive. It also requires more power. In passive matrix display, two transistors control a whole row or column of pixels each at the same time. It is also called Dual-Scan Monitor. Its advantage is that it is less expensive. It uses less power than active matrix displays. The clarity of image is not sharp.

16.3. Touch Screen Monitors: Touch screen monitors is used for input as well as output. A touch screen is a special type of VDU (Video Display Unit). It has a grid of beams or fine wires on the screen. It allows the user to interact with the computer by the touch of a finger rather than typing on a keyboard or moving a mouse. The user enters data by touching icons or menus displayed on the screen. Most touch screen computers use sensors to detect touch of a finger. Touch screens is well suited for simple applications like ATM. It has also become common in departmental stores and supermarkets. The most popularity of touch screen now days is in Mobile phone industry.

16.4. There is more type of display screens but they are not used for computers. Those include Plasma Screens. A plasma display panel (PDP) is a type of flat panel display common to large TV

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displays. They are called "Plasma" displays because the pixels rely on plasma cells, or what are in essence chambers more commonly known as fluorescent lamps. Plasma computer monitors are less commonly used with computers due to their high operating temperatures, high power consumption, and fixed resolution. The future of display screens is OLED (Organic Light-Emitting Diode). An organic light emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compounds which emit light in response to an electric current. This layer of organic semiconductor material is situated between two electrodes. Generally, at least one of these electrodes is transparent. OLED (Organic Light Emitting Display). OLED computer monitors are much thinner and brighter than LCD or Plasma screens. OLED monitors can also be placed on transparent surfaces, such as glass, allowing the user to see through them when not active.

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Lecture 1

Education

Transcript of Lecture 1