1. INFS 211: Introduction to Information Technology
Session 1 – Components and Classification of Computer Systems
Lecturer: Dr. Ebenezer Ankrah, Dept. of Information Studies
Contact Information:

2. Session Overview
Computer systems play a critical role in all aspects of life. This session seeks to introduce students to the components and types of computer systems.
At the end of the session, the student will:
Understand what exactly is the a computer system
Understand the classifications or different types of computer systems
Be able to explain the functions of the various components of a computer system

3. Session Outline
The key topics to be covered in the session are as follows:
The computer hardware
Components of a computer system
Types of computer systems
Information systems

4. Reading List
Alan, E., Kendall, M., & Poatsy, M. A. (2015). Technology In Action Complete (12th ed.). Upper Saddle River: New Jersy. Prentice Hall. (Chapter 2)
O’brien, J. A., & Marakas, G. M. (2011). Management Information Systems (11th ed.). Boston: McGraw-Hill Irwin. (Chapter 1)

5. Topic One
The computer hardware

6. The computer hardware
A computer is a device that can be programmed to accept data, process it into useful information, and store it for reuse.
The computer system has several parts mostly connected with electronic circuits and is normally controlled by programmes (software), which are used to direct how it runs and can accept data (the user input), which it processes into information.

7. The computer hardware
Information is refined and organized data that is meaningful and useful and is output to the user or stored for later use or both.
Information is data that has been processed. The processing makes data to become organized, meaningful and useful.
Data is the raw material that is input into the computer and is yet to be processed.

8. The computer hardware
The principal characteristics of computer systems are:
It responds to a specific set of instructions in a well-defined manner.
It can execute a prerecorded list of instructions (a program).
It can quickly store and retrieve large amount of data.

9. COMPONENTS OF A COMPUTER systems
Topic Two
COMPONENTS OF A COMPUTER systems

10. Components of computer systems
The components of a computer systems are:
Processor
Input devices
Output Devices
Storage Devices
Primary Memory
Secondary Memory

11. Components of computer systems
The components of computer systems

12. Components of computer systems
The processor
This is formally known as the Central Processing Unit (CPU).
The processor uses computer instructions to manipulate input data in its electronic circuitry into information.
It thus executes computer instructions, normally called processing. It is the central control part of a computer.

13. Components of computer systems
Central processing unit (CPU) is the heart of the computer system.
This is the component that actually executes instructions organized in programs (software) which tell the computer what to do.

14. Components of computer systems
The input devices
The input devices accept data in a form that the computer can use and send the data to the processing unit.
The output devices
The output devices make the processed data (information) available in a form suitable to the user.

15. Components of computer systems
Storage devices
The storage devices are normally associated with memory that stores data. There are two types of storage devices and these are:
Primary Memory
Secondary Memory

16. Components of computer systems
Primary Memory is connected to the central processing unit . It is used to hold temporarily, the data and instructions (programmes) that the central processing unit needs in order to process data. This memory is often referred to as primary storage.
Secondary Memory is a kind of storage, which consists of different types of secondary storage devices, which can store additional data and programmes.

17. Components of computer systems
The hardware devices attached to the computer are called peripheral equipment. Peripheral equipment includes all input, output, and secondary storage devices.
In many personal computers, the CPU, memory and disk drives are all contained in the same housing and usually called System Unit. The keyboard (input device) and screen (output device) are separate.

18. Components of computer systems
In larger computer systems, however, the input, processing, output, and storage functions may be in separate rooms, separate buildings, or even separate countries.
Although the equipment may vary widely, from the simplest computer to the most powerful, by and large the four elements of a computer system remain the same: input, processing, output, and storage.

19. Types of computer systems
Topic Three
Types of computer systems

20. Types of Computer Systems
Computers can be generally classified by size and power as follows;
1. Supercomputers
2. Mainframe computers
3. Minicomputers
4. Microcomputers (personal computers)
4.1 Desktop computers
4.2 Notebook computers
4.3 Tablet PC
4.4 Handheld computers (PDA)

21. Types of Computer Systems
SUPERCOMPUTERS
Super computers are the most powerful type of computers. They are so called because of their speed and power. They are so powerful that they can process billions of instructions per second.
Supercomputers are very expensive and are used for specialized applications that require immense amounts of mathematical calculations (number crunching).

22. Types of Computer Systems
These machines are special high-capacity computers used by very large organizations e. g. NASA uses supercomputers to track and control space explorations.
They are also used for major tasks such as worldwide weather forecasting, creating effects on movies, DNA analysis and weapons research. Others include; Scientific simulations, Graphics, Fluid dynamic calculations, Nuclear energy research, Electronic design and analysis of geological data (e.g. in petrochemical prospecting). Perhaps the best known supercomputer manufacturer is Cray Research.

23. Types of Computer Systems
Super computers

24. Types of Computer Systems
MAINFRAME COMPUTERS
Mainframe computers occupy specially wired, air-conditioned rooms. Mainframe computers are capable of great processing speeds and data storage.
Their speed enables them to process millions of instructions per second (MIPS). They were first made in the 1940's and are mainly used by research laboratories, banks, insurance companies and manufacturers.

25. Types of Computer Systems
The main difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.

26. Types of Computer Systems
MINICOMPUTERS
Minicomputers are also known as mid-range computers. They are refrigerator-sized machines. Their power and storage capacity are less than that of a mainframe but higher than that of a microcomputer.
They are meant to be small and offer special purpose services. The difference between minicomputers and mainframe computers have blurred because of the fast development. As a result of this development, the term super-mini has been coined as an appropriate description for the top range of minicomputers.

27. Types of Computer Systems
Minicomputers are used by medium-sized companies or departments of large companies for specific purposes. For example, production departments use minicomputers to monitor certain manufacturing processes or assembly line operations.
They are widely used by retail businesses, colleges and city departments. A minicomputer is a multiprocessing system capable of supporting about 200 users simultaneously.

28. Types of Computer Systems
MICROCOMPUTERS
Microcomputers are also called personal computers. They are the least powerful, yet the most widely used and fastest-growing type of computer. The development of this type of computer has been the fastest.
Personal computers first appeared in the late 1970s. One of the first and most popular personal computers was the Apple II, introduced in 1977 by Apple Computer. Then, in 1981, IBM entered the fray with its first personal computer, known as the IBM PC.

29. Types of Computer Systems
The principal characteristics of personal computers are that they are single-user systems and are based on microprocessors.
The trend in the work environment is to connect these computers to larger size computers (supercomputers, mainframes and minicomputers) and thereby making the microcomputers workstations in the environment of the bigger computers.

30. Types of Computer Systems
There are four types of micro­computers; desktop, notebook, tablet PC, and handheld computers.
Desktop computers are small enough to fit on top of or alongside a desk yet are too big to carry around.
Notebook computers also known as laptop computers are portable.
A tablet PC is a type of notebook computer that accepts handwriting. This input is digitized and converted to standard text that can be further processed by programs such as a word processor.

31. Types of Computer Systems
Handheld computers are the smallest and are designed to fit into the palm of one hand. Also known as palm computers, these systems typically combine pen input, writing recognition, personal organizational tools, and communications capabilities in a very small package. Personal digital assistants (PDA) are the most widely used handheld computers.
The distinction among these computers is based on processing speed and storage capacity. As a result of the fast development in the computer technology, the distinction has blurred considerably since processing speed and storage capacities have increased at all levels.

32. Types of Computer Systems
Some examples of microcomputers

33. Topic Four
INFORMATION SYSTEMS

34. Information Systems
Information System is a collection of hardware, software, people, data and procedures that work together to provide information essential to the running of an organisation. To prepare as a competent end user of computers, we need to understand the basic parts of an information system. It comprises people, procedures, software, hardware and data.
A recent addition to the information system is connectivity. Connectivity has to do with connection to the Internet and the Web. The components of information systems are hardware, software, data, procedures, people and connectivity.

35. Information Systems Hardware
Hardware consists of the physical equipment. It includes the keyboard, mouse, monitor, system unit and other devices.
These parts you can see and touch. They are controlled by software and process data into information. The term “device” refers to any piece of hardware used by the computer, such as a keyboard, monitor, modem, mouse, etc.

36. Information Systems Software
Software (programme) provides step-by-step instructions to control the computer to convert data into information. Software can be divided into two i.e. system software and application software.
System software is background software that exists for the computer's use in helping the computer to manage its own internal resources (tasks and devices).
Application software is the main software that end users use to interact with the computer. They exist for the user, and enable the computer to perform tasks for the user, such as creating documents.

37. Information Systems Data
Data consists of unprocessed facts including text, numbers, images, and sound which the computer can manipulate and process into information that is useful to people. Information is data that has been processed by the computer. The processing makes data to become organised, meaningful and useful.
Computerized data is digital, meaning that it has been reduced to digits, or numbers. The computer stores and reads all data as numbers. Although computers use data in digital form, they convert data into forms that people can understand, such as text, numerals, sounds, and images.

38. Information Systems Procedures
The rules or guidelines for people to follow when using software, hardware, and data are procedures. These procedures are typically documented in manuals written by computer specialists.
Software and hardware manufacturers provide manuals with their products. These manuals are provided either in printed or electronic form.

39. Information Systems People
People are obviously the most important part of the information system. The purpose of information systems is to make people or end users more productive.
People are the computer’s operators, or users. Some types of computers can operate without much intervention from people, but personal computers are designed specifically for use by people.

40. Information Systems Connectivity
Connectivity is an additional part of today's information systems. It allows computers to connect and share information. To be computer competent, end users need to understand information technology (IT).
As a result of the fast development of ICT; data, software procedures and others could be stored at distant locations from where they could be assessed using the Internet. Consequently, connectivity has become an important part of the information system.

41. References
French, C. S. (2001). Data processing and information technology (10th ed.). London, Continuum: Sage Publications Ltd.
Hutchinson, S. E., & Sawyer, S. C. (2000). Computers, communication and information: A user’s introduction (7th ed.). Boston: Irwin McGraw-Hill.
O’Leary, T. J. (2004). Computing today. Boston: McGraw Hill.
O’Leary, T. J., & O’Leary, L. I. (2005). Computing Essentials. Boston: McGraw Hill.
Thompson, R. L., & Cats-Bail, W. L. (2003). Information technology and management (2nd ed.). Boston: Irwin McGraw-Hill.
Williams, et al (2003). Using information technology: a practical introduction of computers and communications. Boston: McGraw-Hill.