Introduction to Computers and Information Systems

Study Unit

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INTRODUCTION TO COMPUTERS AND INFORMATION SYSTEMS

Introduction

This study unit provides a brief overview of computer hardware and software so that as an aspiring accountant, the student will have a basic understanding of how computers operate. This introductory unit will explain some of the common computer terminology, introduce some key concepts related to how computers work, explain the basics about computers, the different categories of computers, hardware and software, and also introduces the concepts of data and information as well as information systems. The study unit alsodefines and introduces the student to the general systems theory (GST).

Of most importance is the fact that the study unit also gives information that the student will require in order to work effectively with computers in an accounting environment.

What is a Computer?

Basically a computer is a device that has the ability to accept data, internally store and execute a program of instructions, perform mathematical, logical and manipulative operations on the data and internally store the data or the result from the earlier described processes and reports on the results. Put in other words, it is an electronic device that is capable of executing instructions, developed based on algorithms stored in its memory, to process data and produce the required results faster than human beings and also store the data or the results for future retrieval.

A computer has four major functions, that is:

• accepts data
• processes data
• produces output
• stores results

This can be represented diagrammatically as follows:

General Systems Theory, Computer System and The Components Of a Computer System

General Systems Theory (GST)

Systems form part of our daily lives. A world without systems would be a disorganized place, with people living their lives without direction.

A system can be defined as a group of parts organized in a body of materials , group of associated bodies moving under gravity eg solar system, working together to produce a wanted result or output. It is a group of interrelated and inter-connected components that depend on each other to fulfill their individual mandates, and by so doing, fulfill the mandate of the whole.

Elements within a system interact with each other to produce information or output and there is a level of dependence on the desired level of output, also known as coupling. Coupling describes how dependent any element is on another and how they relate. Synergy refers to how close the elements are to each other and how they are related to the combined output.

A system maybe man-made or natural, Open or closed

A natural system includes the solar body, ecosystem, human body etc. A man-made system is one that has been made by man e.g. robots, computers, manufacturing machines etc.

Open systems are the most common system types we can come across in everyday life and these are systems that interact with other systems and receive inputs from and they also output to other systems.

Closed systems do not interact with other systems and mostly try to exclude outside environments eg secret societies, Roman Catholic nuns. There is no outside input or output to the outside, but the processing is there.

A system may also be a learning and adaptive system or a non adaptive system, and maybe controlled or non-controlled.

Learning systems are systems that basically adapt to a change in stimulus e.g. human beings learn from an early stage on how to survive in their environment. On the other hand non-adaptive systems are basically systems which once they know what to do, will not change until their basic components are changed e.g. computer programs once installed will not change until the basic composition of the program is changed.

Cybernetic control system

Controlled systems need a range of acceptable status otherwise they are considered out of control or non-controlled. Controlled systems centre on how one condition can be satisfied before the next action can be carried out and this relates to connected elements within a system required to trigger a system.

Linked to the concept of control is cybernetics. The term cybernetics stems from the Greek kybernētēs, the equivalence of steersman, governor, pilot, or rudder. Cybernetics is a broad field of study, but the essential goal of cybernetics is to understand and define the functions and processes of systems that have goals and that participate in circular, causal chains that move from action to sensing to comparison with desired goal, and again to action. Studies in cybernetics provide a means for examining the design and function of any system, including social systems such as business management and organizational learning, including for the purpose of making them more efficient and effective.

Cybernetics was defined by Norbert Wiener, in his book of that title, as the study of control and communication in the animal and the machine. Stafford Beer called it the science of effective organization and Gordon Pask extended it to include information flows "in all media" from stars to brains. It includes the study of feedback, black boxes and derived concepts such as communication and control in living organisms, machines and organizations including self-organization. Its focus is how anything (digital, mechanical or biological) processes information, reacts to information and changes or can be changed to better accomplish the first two tasks. A more philosophical definition, suggested in 1956 by Louis Couffignal, one of the pioneers of cybernetics, characterizes cybernetics as "the art of ensuring the efficacy of action". The most recent definition has been proposed by Louis Kauffman, President of the American Society for Cybernetics, "Cybernetics is the study of systems and processes that interact with themselves and produce themselves from themselves".

Computer System

A computer system is an interrelated system of input, processing, output, storage and control components. Thus a computer system consists of

input and output devices, primary memory and storage devices, the central processing unit within the CPU and other peripherals.

As a system the computer receives data as input, processes it, stores it and then produces output. The computer system functions in the following manner:

• The computer accepts input.

Computer input is whatever is entered or fed into a computer system. Input can be supplied by a person (such as by using a keyboard) or by another computer or device (such as a diskette or CD-ROM). Some examples of input include the words and symbols in a document, numbers for a calculation, and instructions for completing a process, pictures, and so on.

• The computer process data

The computer performs many operations and manipulates the data in many ways.This manipulation is called processing. Examples of processing include performing calculations, sorting lists of words or numbers, modifying documents and pictures according to user instructions, and drawing graphs. A computer processes data in the CPU.

• The computer stores data.

A computer must store data so that it is available for processing. Most computers have more than one location for storing data (the hard drive or C:\, and the floppy drive or A:\). The place where the computer stores the data depends on how the data is being used. The computer puts the data in one place while it is waiting to be processed and another place when it is not needed for immediate processing. The storage of data in the computer is called ‘online storage’ while the storage of data on computer tapes, diskettes or CD-ROMs is called ‘offline storage’.

• The computer produces output.

Computer output is information that has been produced by a computer. Some examples of computer output include reports, documents, music, graphs, and pictures. Output can be in several different formats, such as paper, diskette, or on screen.

To Help You Study
1. Discuss the purpose of information in a business environment.
2. Briefly discuss the characteristics with which information should comply.
3. Briefly discuss the qualities against which information should be evaluated in order to be useful to an organisation.
4. Briefly discuss a cybernetic control system.

Categories of Computers

Computers can be generally classified by size and power; although there are considerable overlaps. There are personal computers (PC), mini-computers, mainframe computers, servers, workstations and supercomputers. The following are descriptions of several types of computers.

Personal computers

The personal computer (PC) is a small sized, relatively inexpensive computer designed for an individual user. The most common PCs are the IBM compatible and the Macintosh compatible machines, named after the two major computer manufacturers. PCs may be called desktop computers, which stay on the desk or laptop computers, which are lightweight and portable.

PCs run programs, such as word processors, desktop publishing, spreadsheets and databases management, which are designed to help individuals accomplish their work more productively.

Servers

Servers are not designed to be used directly. They make programs and data available for people hooked up to a computer network, that is, a collection of computers connected together so that they can exchange data.

Minicomputers

Minicomputers are midsize multi-user systems that can handle the computing needs of a smaller corporation or organization. Many people use them simultaneously by means of remote terminals or personal computers.

Mainframe computers

Mainframes are huge and powerful multi-user systems designed to handle gigantic processing jobs in large corporations or government agencies. Mainframes are the largest and most expensive computers which are designed for large scale processing. Mainframe computers can be used by many users at the same time. They can support concurrent programs, which means, they can perform different actions or processes at the same time. In education, they are used by scientist and researchers for complex mathematical calculations. They are also used for control systems in banking, for example Zim-Switch.

Workstations

A workstation is similar to a personal computer in that it supports a single user but it is more powerful and often comes with a high-quality monitor. They also have the capacity to store and process large quantities of data. This is mainly because workstations are commonly used to support applications that require relatively high quality graphics capabilities and a lot of memory, such as desktop publishing, software development and similar projects. In most cases workstations are linked together to form a computer network called a local area network (LAN), which means that several people, such as students in class, can communicate with each other and share electronic files and information.

Supercomputers

Supercomputers are ultra fast computers designed to process high amounts of scientific data then display the underlying patterns that have been discovered.

To Help You Study

1. Define the control unit and give four (4) of its functions.

2. Briefly discuss mainframe computers, servers and workstations. Why is it important to compare computers?

Components of a Computer

A computer is made up of two major components, namely hardware and software.

Software is the invisible instructions that control the hardware and make it work. These instructions are written in a programming language to help simplify the development of applications.

The next two study units will look at these two concepts in greater detail.

Study Unit

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HARDWARE

Computer hardware refers to all the physical components of the computer both mechanical and electronic. That is input and output devices as well as its internal components.

Computer hardware are devices that surround the system unit, for example the keyboard, mouse, speakers and the monitor are specifically known as peripheral hardware devices.

Basically a computer consists of five primary hardware components:

• the central processing unit (CPU),
• memory,
• input devices,
• output devices and
• storage devices.

These components work together with software to process the input and produce the required output. The following schematic diagram gives the layout of a personal computer (PC), most single user systems follow this general design.

Figure 9.1: Components of a computer system

The Central Processing Unit

The central processing unit (CPU) or the system unit, is the main part of a computer system like the heart of a human being. It is the part of the computer that retrieves instructions from the memory of the computer and executes them one by one. The CPU contains electronic clocks that control the timing of all operations; electronic circuits that carry out arithmetic operations like addition and multiplication, circuits that identify and execute the instructions that make up the programs and circuits that fetch the data from memory.

Computers depend primarily on microprocessors for processing (manipulating) input. Note that CPUs are not all equal. Some process data faster that others. It is therefore important that you know what kind of CPU your computer contains. The CPUs of older PCs were numbered: 286, 386, and 486. These processors are now obsolete, and you are likely to have difficulty finding suitable software to run on computers equipped with them. These numbered central processors were followed by the Pentium series, which are Pentium I to IV. Nowadays the range of processors is even wider.

When determining what type of computer to buy, it is important for you to know that the terms 286, 386, 486, and Pentium refer to the types of processors in the computer. New computers these days have Pentium microprocessors and older ones will have microprocessors from the X86 family. The later are no longer being manufactured and can only be obtained as second hand computers. It is also important that you know the type of processor in your computer. Some newer computers will not run on older processors and some newer processors are too sophisticated for older software.

The speed of CPUs is measured in hertz.A hertz is one cycle per second.All computers have a clock built into them for timing the cycles. The clock is usually located in a small metal box on the motherboard.Today, many CPUs can complete over six (6) instructions per second. The system clock determines the speed at which the computer can execute an instruction, and therefore limits the number of instructions the computer executes within a given time. The clock speed should be considered when purchasing a personal computer. Most modern software will run satisfactorily on processors with a clock speed of 350MHz or higher. MHz stands for megahertzs. A MHz is 1,000,000 cycles per second. Faster clock speeds are normally expressed in Gigahertz (GHz).

Although physically a single component, the CPU is logically made up of a number of sub-parts. The CPU has three basic parts, namely the control unit (CU), arithmetic logic unit (ALU) and registers.

The Control Unit

The CU controls and co-ordinates the actions of the other components of the computer system. It directs the flow of information into the CPU and/or memory or storage. It also controls which instructions the CPU will do next.

The Arithmetic Logic Unit (ALU)

The arithmetic logic unity (ALU) contains circuits that manipulate data. As the name suggests this is responsible for all mathematical operations. It receives data from the Control Unit and performs either Arithmetic operations (add, subtract, multiply and divide) or Logic operations (making a comparison and take an action based on the result) for example If a=2 End, Else Begin. This example shows that if a was equal to 2 the program should end and if it is not true it should start the operation again. Some common logic comparison symbols:

• = equal to
• < less than
• > greater than
• <= less than or equal to
• >= greater than or equal to
• > not equal

Computer Memory

Computer memory is used to store information and programs. Computer memory is also known as Internal memory, Main Memory or Primary Memory. It is found in the system unit on the mother board. It consists of silicon chips, usually either VLS or VLSI technology is used to create the chips.

Primary Memory

There are basically two types of primary memory that is Random Access Memory (RAM) and Read Only Memory (ROM). ROM has other variations such as the PROM, EPROM and EAROM .

Random Access Memory

RAM is considered as the working memory. It provides the working area in which the computer stores the programs it runs, performs its calculations and stores intermediate results. When using a program, the computer loads a portion of the program from the hard drive to RAM, which is a much faster memory. RAM stores all the programs and data before it can be send to a permanent storage medium such as the hard drive.

Access to information is random access.Random access means that any piece of information in RAM can be accessed at any given time without accessing other information first. It is like the tracks on a music CD. You can access any track at any time and in any order.The other kind of access is sequential access. You must access the information in the order that they are located. This is like a music tape. You must play the songs in order, or you have to fast forward past songs to get to the one you want. Note that RAM is emptied the moment the computer is switched off. This is the reason why RAM is often referred to as volatile memory. This means that its contents are lost when the computer is turned off. The computer therefore has to have some means of storing programs and data permanently.