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Introduction to Information Systems

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  1. Identify and discuss the role of the essential hardware components of a computer system.
  2. Identify and briefly describe the functions of the two basic kinds of software.
  3. Outline the role of operating systems.
  4. Learn how to measure data.
  5. Outline the overall evolution of programming languages and highlight the differences between programming languages used by and users and IS professionals.


Case Study: Home Depot - Putting Hardware and Software Together to Meet Customers' Needs

Home Depot is the world's largest home improvement retailer, with over 1,900 stores planned for 2004. The company's stores cater to do-it-yourself, as well as home improvement, construction, and building maintenance professionals. Home Depot's Expo Design Centers are standalone stores that include interior design showrooms staffed with employees who can plan and coordinate home improvement projects for customers. A one-stop full-service interior design center, each Expo store is filled with showroom after showroom of exciting ideas, hundreds of full-size displays, and lots of friendly, knowledgeable professionals who can help customer with any project, big or small.

Expo Design Center customers have their own project designer to work with them from the very beginning, assisting in the selection of products, styles, and colors that best suit their lifestyles. once the details are settled, a project superintendent can take over and work with the contractor and installers to complete the job. Until recently, customer planning and ordering in the Expo Design Centers was done manually - a complicated nightmare for both customers and Home Depot staff, with workers flipping through paper catalogs and then entering special purchase orders into Home Depot's existing ordering system. Interior designers and project coordinators who supervise installations had to use file folders and pieces of paper to tract the many details.

Since the key to success of the Expo Design Centers is personal one-on-one attention and follow-up with customers, the old system clearly wasn't acceptable. HOme Depot recognized the need for improved computer hardware and software to provide this high level of customer support. The company bought powerful computers, linked them in a network, and developed software to enable employees to view products, create purchase orders for customers, and track the progress of projects. Now products can be viewed easily and ordered directly with the new system. Room measurements and installation schedules are also entered into the tracking system, so all the details, needed to track and follow up on home improvement projects are at the fingertips of the Home Depot project superintendents. The new software uses "storyboards" that lead users through a task step by step, thus minimizing training requirements for employees, most of whom have construction and trade backgrounds.

Points to considers:

1 What are the various kinds of hardware and software and how are they used?

2 Where can software be obtained, and what are th pros and cons of each approach?

1-1 Overview of a computer system

All physical parts of the computer (or everything that we can touch) is known as hardware. All of the components of a computer system can be summarized with the simple equations below..

Software gives "intelligence" to the computer.

Basically all computers, regardless of their size, have the same general design which consist of the following units: the central processing unit (CPU), memory, and input/output circuitry which are situated on the printed circuit board, also called the system board or motherboard (figure of a motherboard).












Figure 2. This diagram describes the relationships between the components of the computer system.

The microprocessor is an integrated circuit that contains transistors, diodes, resistors, and other components interconnected to form the electronic circuit. The circuit is mounted in a metal or plastic package and connections are welded to external pins. The circuit can be accessed only through these pins. This design produces the following benefits:

a reduction in size, cost, and power consumption;
an increase in operating speed;
a higher reliability.

Large computer systems can have many processors, so they are called multiprocessor systems. The microcomputer is a system with a single processor that fits on a single chip. This processor is called a microprocessor.

The RAM and ROM chips provide memory to the computer. One of the most important characteristics of memory is the amount of information it can hold.

The input/output(I/O) devices are external devices (in relation to the CPU) that are connected to the computer to provide means of the communication between the user and the computer.

Disks (floppy, hard, or optical) and tapes are used to store information for long periods of time.

Peripheral devices are connected to the computer through ports, or sockets, that are mounted outside. Some peripherals (e.g. disk drives) are located inside the computer case, so they are connected via expansion slots.


a). The back of the computer showing the ports and sockets

b). Expansion slots

Figure 3. How peripheral devices are connected to the computer


The main unit inside the computer is the CPU. This unit is responsible for all events inside the computer. It controls all internal and external devices, performs arithmetic and logic operations. The operations a microprocessor performs are called the instruction set of this processor. The instruction set is "hard wired" in the CPU and determines the machine language for the CPU. The more complicated the instruction set is, the slower the CPU works. Processors differ from one another by the instruction set. If the same program can run on two different computer brands they are said to be compatible. Programs written for IBM compatible computers will not run on Apple computers because these two architectures are not compatible.

There is an exception to this rule. Apple Macintosh with a program SoftPC loaded can run programs written for IBM PC. Programs like SoftPC make one CPU "pretend" to be another. These programs are called software emulators. Although software emulators allow the CPU to run incompatible programs they severely slow down the performance.

The CPU is composed of several units...

Diagram 1. A simplified diagram of the CPU

 The control unit directs and controls the activities of the internal and external devices. It interprets the instructions fetched into the computer, determines what data, if any, are needed, where it is stored, where to store the results of the operation, and sends the control signals to the devices involved in the execution of the instructions.

The arithmetic and logic unit (ALU) is the part where actual computations take place. It consists of circuits which perform arithmetic operations (e.g. addition, subtraction, multiplication, division) over data received from memory and capable to compare numbers.

While performing these operations the ALU takes data from the temporary storage area inside the CPU named registers. Registers are a group of cells used for memory addressing, data manipulation and processing. Some of the registers are general purpose and some are reserved for certain functions. It is a high-speed memory which holds only data for immediate processing and results of this processing. If these results are not needed for the next instruction, they are sent back to the main memory and registers are occupied by the new data used in the next instruction.

All activities in the computer system are composed of thousands of individual steps. These steps should follow in some order in fixed intervals of time. These intervals are generated by the clock unit. Every operation within the CPU takes place at the clock pulse. No operation, regardless of how simple, can be performed in less time than transpires between ticks of this clock. But some operations require more than one clock pulse. The faster the clock runs, the faster the computer performs. The clock rate is measured in megahertz (Mhz) or million ticks per second.

The two main features of the CPU are

its speed measured in millions of instructions per second;
the word size.

The word size is the number of bits the CPU can process at a time. An 8-bit processor manipulates with 8 bits simultaneously. Consider a simplified example: the CPU needs to add up two four-digit numbers. For an 8-bit CPU, it will take four operations, a separate operation for addition of each of the four digits. A 16-bit processor will be able to work on two digits simultaneously, so it will need only two operations. A 32-bit processor will complete addition in one operation.

Intel 80486 is a 32-bit processor so it can manipulate twice as much data at one time as, say, Intel 80286 which is a 16-bit processor. The maximum possible word size at the time of writing of these notes is 64 bits. Most supercomputers have such powerful processors. What is amazing that modern technology allows to produce 64-bit processors for personal computers and Pentium Pro would be one of the examples. The 32-bit processors are installed in many personal computers, minicomputers, and in most mainframes.

Today, there are two leading manufacturers of microprocessors : Intel and Motorola. Other microprocessors are compatible with them. For example, AMD-K5 is compatible with Pentium.


There are two main types of memory inside the computer.

Read-only-memory (ROM) is a chip or a group of chips containing programs, tables of constants and instructions for the CPU. Only the CPU has access to this memory. For example, when we turn on the computer, the CPU gets its first instructions from the ROM. These instructions are burnt into the chip with the help of special equipment before the chip is installed inside the computer. Users do not have access to the ROM, so they can't change these instructions.


Users work with the random-access-memory (RAM). RAM is a collection of cells and we can access any cell at any given time, hence the name random access memory.

RAM is often referred to as main memory or primary storage. RAM usually occupies a number of chips connected together. It is used to store programs and data being used by these programs while the computer is on. When the computer is turned off any information is erased from the RAM. That is why RAM is often called volatile while ROM is a non-volatile type of memory.


Every cell in the memory is assigned a unique number called a memory address. It is hard to remember memory addresses as numbers so many programming languages allow to refer to cells with alpha-numeric names. For example, when the computer gets the instruction NUMBER1=3, it allocates a free cell in the primary storage, names it NUMBER1 and writes 3 in it. From that moment this cell is occupied by 3 and we can read its content many times using the cell name NUMBER1 as a reference to it in different instructions. Every time we refer to the cell, the copy of its content is used by the instruction. So we write data once but we can read it many times until it is overwritten by something else.


1-4 Peripheral devices

Peripheral devices are devices connected to the computer but external in relation to the processing unit. If a peripheral device is disconnected, the computer will still be able to work; only functions performed by this peripheral device will not be available. For example, if you disconnect a keyboard, you would not be able to type in information but you will be able work with the graphical user interface by clicking the mouse. If you remove the hard disk, you will have to start up your computer using floppy disk and you will have to save your data on floppy disks only but the computer will still be working.

Peripheral devices can reside inside the computer case or outside. For example, a mouse, a keyboard, a monitor are always outside the case and they are connected to the computer via ports which are situated on the back of the case. Disk drives are positioned inside the case and they are connected to the motherboard via disk controller cards which are inserted in the expansion slots on the motherboard.

Peripheral devices are classified according to the purpose they serve:
Input devices are used for data input
Output devices are used for data output
Storage devices are used to store data for long periods of time

Input Devices

The purpose of input devices is to translate data and information from human-readable format to electrical impulses.

The most popular input devices are the keyboard and the mouse. We can type in commands using a typewriter part of the keyboard or we can use arrows to highlight items in menus and we press Enter to make a selection. Quicker way of making selection in the menu system is to move the mouse pointer and click the button.

Scanners are devices suitable for entering of graphical information into the computer. Some scanners are able to read text so this way of entering textual information will be much quicker than typing.




Other input devices:

1.        Voice- recognition devices:


2.        Digital computer cameras:


3.        Terminals:


4.        Scanning devices:


5.        Point –of –Sale (POS) Devices: POS devices are terminals used in retail operations to enter sales information into the computer system. The POS device then computes the total charges, including tax. Many POS devices also use other types of input and output devices, such as keyboards, bar code readers, printers, and screens.


6.        Automatic Teller Machine (ATM) Devices: This is another type of special-purpose input/output device, the automatic teller machine (ATM), is a terminal most bank customers use to perform withdrawals and other transaction for their bank accounts.


7.        Touch-Sensitive Screens.


8.        Bar Code Scanners.




Output Devices

The purpose of the output devices is to translate data and information from electrical impulses to human-readable format.

The output device which is necessary for the computer to display messages to the user is a monitor. If we want to keep the copy of the work on paper, we use printers. Plotters are devices that are more suitable for the output of high quality graphics.



Other output devices:

1.        Display monitors:


2.        Liguid Crystal Dispalys (LCDs)


3.        Earphone:



Secondary Storage


Secondary storage devices hold files that are not currently being used. For a file to be used it must first be copied to main memory first. After any modifications files must be saved to secondary storage. It is advisable to save your data files at the regular intervals as you work on them as data can be lost unexpectedly because of various reasons like interruption in power supply, memory management problems, freezing keyboard, etc.

As secondary storage media can be damaged and files on them become corrupted, it is suggested to make back-up copies of valuable files on a regular basis. Lots of people skip the last but very important step in the backup procedure - check that the backup copy of files is not damaged.


The Difference Between Primary and Secondary Storage.

·         Primary storage is volatile: when the power is off, all contents of RAM are lost. That is why data from RAM is saved as files on secondary storage which is non-volatile and almost permanent (It wears out eventually or becomes out of dated technology)

·         Size. Secondary storage is virtually infinite: when you run out of space on one disk, you use another. On the contrary there is a limited amount of RAM that can be accessed by the CPU. Some programs will not run on a particular computer system because there is not enough RAM available.

1.        RAM chips are located on the motherboard so the distance the electrical signals have to travel from the CPU to RAM or in the opposite direction is much shorter compared to the distance between the CPU and secondary storage devices. The shorter the distance, the faster the processing.

2.        Also working with the secondary storage involves mechanical operations like spinning


Storage Hierarchy.

The various levels of memory from registers to cache, to primary, to secondary storage have decreasing cost and speed and increasing capacity.

Type of Memory

Access Speed



Registers (inside the CPU)








Primary storage




Secondary storage




Types of Access

Secondary storage devices provide direct access to data or sequential access.

Direct access, also called random access, means that the system maintains a list of data locations and the required piece of data can be found quickly. The most common direct access storage is the disk. The most popular types of disks today are floppy disks, hard disks and optical disks.

Sequential access means the computer system must search the storage device from the beginning until it finds the required piece of data. The example would be a magnetic tape where data is stored sequentially and can be processed only sequentially.


Secondary Storage Devices:

1.        Magnetic Tapes:



2.        Magnetic Disks:


3.        RAID (redundant array of independent/inexpensive disks):


4.        SAN (storage area network):


5.        Optical Disks:


a.        CD-ROM

b.       CD-W

c.        CD-RW


6.        Magneto-Optical Disk


7.        Digital Video Disk


8.        Memory Cards


9.        Expandable Storage Devices:

2,3 Software and operating systems

A computer cannot do anything without instructions. Sets of instructions are called programs. Programs and data are used to control the hardware of the computer system and to interface the user to a PC. Programs and data are called software. Whatever you want your computer to do, you give your instructions using software.

Software is usually classified as system software and application software.

The most important system software is an operating system. You can consider an operating system as an interpreter between the user, application software and hardware.The operating systme, executes a variety of activities, including the following:

1.        Performing common computer hardware functions

2.        Providing a user interface

3.        Providing a degree of hardware independence

4.        Managing system memory

5.        Managing processing tasks

6.        Providing networking capability

7.        Controlling access to system resources

8.        Managing files

The table below classifies software and gives examples for each group.




Operating Systems

Word Processors



Windows 2000/XP

Word Perfect

Windows NT

Ami Pro

MacOS (e.g. System 7)





Lotus 1-2-3


Quattro Pro



Norton Utilities




Windows 3.x




Virus Buster

Paint Shop Pro


Corel Photo Paint

Virus Scan

Corel Draw








Another type of software is programming languages. Programming languages are used to create all other software whether it is system or application software. Modern programming environments have graphical user interfaces (GUI) featuring symbolic icons and drag-and-drop technique and English-like statements. Delphi and Visual Basic are the most popular examples of such environments. Programming in visual environment creates an impression that it is very easy to write programs. But becoming a good programmer requires talent, ability to learn, logic, creativity, patience and experience.

Software can be categorised as open system or proprietary.

Open system software can be modified for use with any hardware. It is not the exclusive property or design of a particular vendor. For example, UNIX is the first operating system that works on minicomputers, mainframes and PCs. Its inner workings are available to public and anyone can adapt it or develop applications to work with it.

The proprietary products are designed for particular systems and cannot be used with other hardware. Its inner workings are protected information. For example, Apple computers and software for them have been proprietary products for many years. Only recently Apple licensed its MacOS to other hardware companies to build Macintosh clones.

4. How to measure data


Data inside the computer is represented in form of electrical pulses, when high voltage is often denoted by 1 (or on) and low voltage is denoted by 0 (or off).

Because we are using only two digits, 0 and 1, for data representation we are actually using the binary number system, where 0 and 1 are often referred to as binary digits. The abbreviation of "binary digit", bit, is accepted as a basic unit when we measure amounts of information. All keys on the keyboard are coded with the combination of 0s and 1s. When you press any key, a corresponding sequence of 0s and 1s is sent to the memory inside the computer .

When a computer gets the sequence of binary digits, how can it know when the first character stops and the next one starts? The easiest solution was to make all characters to consist of the same number of digits. But how many digits?

First how many characters do we need to code? 26 upper case letters, 26 lower case letters, 10 decimal digits, punctuation and lots of special characters. Altogether to cover all these characters and all keys on the keyboard we need 256 codes. With one digit we can code two characters only. With two digits we can code 22 = 4 characters. If we proceed this way, we'll get the following table of powers of 2:

From the table we can see that to represent 256 characters we need 8 digits. What to do if the binary representation of a character is less than 8 digits? For example, upper case letter A is coded as 65 using decimal system which is 1000001 in binary. There are only 7 digits here. Place leading 0 (zero) and you get 8 digits without changing the actual value of the number (like in decimal system 5, 05 or 005 will have the same value).                                                         

So every character occupies 8 bits of memory or 8 bits of secondary storage. The word "HELLO." consists of 6 characters (5 letters and one full stop) and occupies 6*8=48 bits. The word "computer" consists of 8 characters and occupies 8*8=64 bits. Whatever amount of information you measure in bits, you will always get a multiple of 8. That is why another unit of measure, called byte, was introduced.

 A group of 8 bits is called a byte.

As amounts of data being processed keep growing, other units of measure were created.

1 Kilobyte = 1024 bytes

Outside computing, a kilo means 1000. However, in computer environment, all measures should be powers of 2 and closest to 1000 will be 1024 which is 210. Kilobyte is often abbreviated as K or Kbyte.

Today computer memory is measured in thousands of kilobytes or Megabytes and secondary storage is measured in millions of kilobytes or Gigabytes. A Megabyte is often represented as Mbyte or M. A Gigabyte is abbreviated as G.

1 Megabyte = 1024 K = 10242 bytes

1 Gigabyte = 1024 M = 10242 K = 10243 bytes

1 Terabyte = 1024 G = 10242 M = 10243 K = 10244 bytes

In programming languages, a variable is a named memory location created to keep data. But what amount of data? This depends on the type of the variable. If a variable is of type character, it will occupy only 1 byte of memory. A variable of type integer on a personal computer in most programming environments will occupy 2 bytes of memory. For example, if variable named Number is of type character and holds the value of `4' it will occupy only one byte. But if it is of type integer with the value 4, it will occupy 2 bytes.

About Standards: Latin 3 and Unicode

5. The evolution of Programming Languages

First-Generation Languages: The first generation of programming languages is machine language, which required the use of binary symbol (0s and 1s). As this is the language of the CPU, text file translated into binary sets can be read by almost every computer system platform.

Second-Generation Languages: Developers of programming languages attempted to overcome some of the difficulties inherent in machine language by replacing the binary digits with symbols programmers could more easily understand. Assembly languages use codes like A for add, MVC for move, and so on. This second-generation language was termed assembly language.

Third-Generation Languages: Third-generation language continued the trend toward greater use of symbolic code and away form specifically instruction the computer how to complete an operation. BASIC, COBOL, C, and FORTRAN are examples of third-generation languages that use English like statements and commands.

Fourth-Generation Languages: Fourth-generation programming languages emphasize what output results are desired rather than how programming statements are to be written. Prime examples include Visual C++, Visual Basic, PowerBuilder, Delphi, and SAS.Another popular fourth-generation language is called structured query languages (SQL), which is often used to perform database queries and manipulations.

Fifth-Generation Languages: With fifth-generation languages, you do not tell the computer how to do a job, but what you want it to do, and it figures out what you need. Java Studio is an example of this type of language. It is so simple to use that you can easily develop a working program without any previous programming experience.

Object-Oriented Programming Languages: Examples of this type of languages are Smalltalk, C++, and Java.


Assignment 2::

1.With your classmates, visit a major computer retail store. Spend some time there during which each of you concentrates on identifying the latest developments in processing, input,output and secondary storage devices. Use Word Processing software to write a brief report summarizing your findings.

2. Your mother is willing to give you 2000 Canadian Dollors to buy a new set of computer. With this limited buget, you need to find out what is the best deal for you in terms of satisfying your needs in an economical way. List the main componets of your hardware and how much do you have to pay for each of them.

How To Purchase and Install a Personal Computer.

Work Cited:

Fundamentals of Information Systems: Ralph M. Stair , George W. Reynolds.

Tanya Linden
Mark Mackowiak - graphic design

© UMTC, 1996-1997

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