Download Computer Fundamentals: Generations, Classification, and Processing and more Study notes Computer Science in PDF only on Docsity!
lOMoAR cPSD| 47802020
ICS 2174: INTRODUCTION TO COMPUTER SCIENCE
COURSE OUTLINE
Objectives
- Enable the student understand the general overview and fundamental components of a computer system.
- Equip the student with the necessary skills to operate the computer. No. Topic Sub-topic
- Introduction to Computer Fundamentals Computers Classification of Computers
- Software Application software; customized, general purpose
- System software; operating systems, utilities
- Hardware Input devices; Output devices; Storage devices
- Assessment 1 Revision and Continuous Assessment Test 1
- Computer Processing Central Processing Unit
- Components of the CPU
- Role of the CPU
- Operating Systems Functions of Operating Systems
- Categories of Operating Systems
- Data Representation Data Representation; Bits, Bytes, Character codes
- Number systems, binary, octal, decimal, etc,
- Assessment 2 Revision and Continuous Assessment Test 2
- Introduction to Computer Types of networks: -Advantages/ disadvantages of Networks networks Network topologies
- Introduction to the World Wide Web (WWW) Internet Web browsers
- Application Software Word Processing:- Ms Word Packages Spreadsheets:-Ms Excel Presentations:- Ms PowerPoint
- Assessment 3 Assignment and Revision Assessment:
- Continuous Assessment Tests 20%
- Assignments 10%
- End of Semester Exam 70% Total 100% References:
1 Norton P (2006) Introduction to Computers (5thEdition); New York, USA McGraw Technology Education
- Caplon H (2004) Computers: Tools for an Information Age (8th^ Edition); Addisson Wesley
- Shelly Cashman Series, Discovering Computers 2010, Living in a Digital World
- Shelly G. B., Cashman T. J. & Vermaat M. E. (2002). Microsoft Office. Shelly Cashman Series. 1.0 INTRODUCTION TO COMPUTERS Preview Computers are machines that perform tasks or calculations according to a set of instructions, or programs. The first fully electronic computers, introduced in the 1940s, were huge machines that required teams of people to operate. Compared to those early machines, today's computers are amazing. Not only are they thousands of times faster, they can fit on your desk, in your lap, or even in your pocket. Computers work through an interaction of hardware and software. Hardware refers to the parts of a computer that you can see and touch, including the case and everything inside it. The most important piece of hardware is a tiny rectangular chip inside your computer called the central processing unit (CPU), or microprocessor. It's the "brain" of the computer—the part that translates instructions and performs calculations. Hardware items such as your monitor, keyboard, mouse, printer, and other items are often called hardware devices. Software refers to the instructions, or programs, that tell the hardware what to do. A word processing program that you can use to write letters on your computer is a type of software. The operating system (OS) is software that manages your computer and the devices connected to it. Two well-known operating systems are Windows and Macintosh operating system. Your computer most likely uses the Windows operating system. Computers Fundamentals Computer can basically be defined as an electronic device that receives (raw) data, transforms (processes) that data and produces (meaningful) output as information with the capability of storing the data/information for future retrieval. Data can be anything like marks obtained by you in various subjects. It can also be name, age, sex, weight, height, etc. of all the students in your class or income, savings, investments, etc. Thus, a computer of any type irrespective of their size and make perform basically four major operations or functions. These are
- it accepts data or instructions by way of input,
- it stores data,
- it processes data as required by the user, and4) it gives results in form of output.
2.0 CLASSIFICATION OF COMPUTERS Computers can be classified according to a number of parameters such as function, size, age or generation, etc. Generally, a computer with high processing speed and large internal storage is called a big computer (Size!). Due to rapidly improving technology, there is always confusion among the categories of computers. 2.3 Classification of computers by age/generation The history of computer development is often referred to in reference to the different generations of computing devices. A generation refers to the state of improvement in the product development process. This term is also used in the different advancements of new computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and computer memory has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play. Each generation of computers is characterized by major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices. First Generation – 1950s-1960s: Vacuum Tubes The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language to perform operations, and they could only solve one problem at a time. Machine languages are the only languages understood by computers even today. While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers. Computer Programmers, therefore, use either high level programming languages or an assembly language programming. An assembly language contains the same instructions as a machine language, but the instructions and variables have names instead of being just numbers. Programs written in high level programming languages are retranslated into assembly language or machine language by a compiler. Assembly language program retranslated into machine language by a program called an assembler (assembly language compiler). Input was based on punch card and paper tapes, and output was displayed on printouts. ENIAC (Electronic Numerical Integrator and Calculator/Computer): It was the first electronic computer built in 1946. The ENIAC was 30 50 feet long, weighed 30 tons, contained 18,000 vacuum tubes, 70,000 registers, 10,000 capacitors and required 150,000 watts of electricity. Today an average personal computer is many times as powerful as ENIAC, still size is very small. The ENIAC soon became obsolete as the need arose for faster computing speeds. Punched card system of a machine, Inside of a vacuum tube with plate cut open.
Third Generation – 1970s-1980s: Integrated Circuits The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers. Silicon is the basic material used to make computer chips, transistors, silicon diodes and other electronic circuits and switching devices because its atomic structure makes the element an ideal semiconductor. Silicon is commonly mixed with other elements, such as boron, phosphorous etc, to alter its conductive properties. A chip is a small piece of semi conducting material (silicon) on which an integrated circuit is embedded. A typical chip is less than ¼-square inch and can contain millions of electronic components (transistors). Computers consist of many chips placed on electronic boards called printed circuit boards. There are different types of chips. For example, CPU chips (microprocessors) contain an entire processing unit, whereas memory chips contain blank memory. Computer chips, both for CPU and memory, are composed of semiconductor materials. Semiconductors make it possible to miniaturize electronic components, such as transistors. Not only does miniaturization mean that the components take up less space, it also means that they are faster and require less energy. Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors. Fourth Generation – 1980s -Present: Microprocessors The microprocessor brought the fourth generation of computers, as more millions of integrated circuits were rebuilt onto a single silicon chip, (VLSI). In the world of personal computers, the terms microprocessor, microchip, chip and CPU are used interchangeably. At the heart of all personal computers sits a microprocessor. Microprocessors also control the logic of almost all digital devices, today, from clock radios to fuel-injection systems for automobiles. In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUI's, the mouse and handheld devices Fifth Generation Computers Assignment Carry out some research and come up with a clear description of the fifth generation computers 2.2 Classification of computers by Function Servers Server usually refers to a computer that is dedicated to providing a service. For example, a computer dedicated to a database may be called a "database server". "File servers" manage a large collection of computer files. "Web servers" process web pages and web applications. Many smaller servers are actually personal computers that have been dedicated to providing services for other computers. Workstations Workstations are computers that are intended to serve one user and may contain special hardware enhancements not found on a personal computer. Embedded computers Embedded computers are computers that are a part of a machine or device. Embedded computers generally execute a program that is stored in non-volatile memory and is only intended to operate a specific machine or device. Embedded computers are very common. Embedded computers are typically required to operate continuously without being reset or rebooted, and once employed in their task the software usually cannot be modified. An automobile may contain a number of embedded computers; however, a washing machine and a DVD player would contain only one. The central processing units (CPUs) used in embedded computers are often sufficient only for the computational requirements of the specific application and may be slower and cheaper than CPUs found in a personal computer. Information appliances Information appliances are computers specially designed to perform a specific user-friendly function —such as playing music, photography, etc. The term is most commonly applied to mobile devices, though there are also portable and desktop devices of this class. 2.3 Classification of computers by Size!
computer. The laptop computer is portable and fully functional microcomputer. It can be used on your lap in an airplane, thus it is referred to as laptop computer. The memory and storage capacity of laptop computer is almost equivalent to the PC or desktop computer or even more. It also has the hard disc, CD-ROM drive, CD-writer etc. it has built-in keyboard and built-in trackball as pointing device. Laptop computer is also available with the same processing speed as the most powerful personal computer. It means that laptop computer has same features as personal computer. Laptop computers are more expensive than desktop computers. Normally these computers are frequently used by business travelers. b. Handheld computer In the mid 1990s, many new types of small personal computing devices have been introduced and these are referred to as handheld computers. These computers are also referred to as Palmtop Computers. This type of computer is named as handheld computer because it can fit in one hand while you can operate it with the other hand. Because of its reduced size, the screen of handheld computer is quite small. Similarly it also has small keyboard. Some handheld computers have a specialized keyboard. These computers are used by mobile employees, such as meter readers and parcel delivery people, whose jobs require them to move from place to place. E.g. Personal Digital Assistance, cellular telephones (Mobile phones), Etc 3.0 COMPUTER SOFTWARE Take note that computer cannot do anything without instructions from the user. In order to do any specific job you have to give a sequence of instructions to the computer. This set of instructions is called a computer program. Software therefore refers to the set of computer programs (set of instructions), procedures that describe the programs and how they are to be used so that a task can be accomplished in the computer. We can say that it is the collection of programs, which increase the capabilities of the hardware. Software guides the computer at every step where to start and stop during a particular job. The process of software development is called programming. Note that software and hardware are complementary to each other. Both have to work together to produce meaningful result. Also producing software is difficult and expensive. Thus software is a generic term for organized collections of computer data and instructions, often broken into two major categories: application software which is used by users to accomplish specific tasks and system software that provides the basic non-task-specific functions of the computer.
There are two categories of computer software: application software and system software. (a) Application software Application software consists of programs that perform specific tasks for users. Popular application software includes word processing software, spreadsheet software, database software, and presentation graphics software. Application software can be packaged software (general purpose software that meets the needs of a variety of users), custom software (tailor-made software developed at a user’s request). Application software can be used as a productivity/business tool; to assist with graphics and multimedia projects; to support home, personal, and educational activities; and to facilitate communications. Specific application software products, called software packages, are available from software vendors. Examples of Applications Software People use application software to become more effective, efficient and productive while performing daily activities. Word processing software allows users to create and manipulate documents that contain text and graphics. With word processing software, you can insert clip art into a document; change margins; find and replace text; use a spelling checker to check spelling; place a header and footer at the top and the bottom of a page; and vary font (character design), font size (character scale), and font style (character appearance). With spreadsheet software, data is organized in rows and columns, which collectively are called a worksheet. The intersection of a row and column, called a cell, can contain a label (text), a value (number), or a formula or function that performs calculations on the data and displays the result. Database software allows you to create and manage a database. A database is a collection of data organized to allow access, retrieval, and use of that data. A query is used to retrieve data according to specified criteria, which are restrictions the data must meet.
T y p e s o f S o f tw a r e
Software
ApplicaƟon
SoŌware
General purpose
SoŌware
(Packages)
Special purpose
soŌware (Custom)
Sys tem
SoŌware
OperaƟng
Systems
UƟliƟes
Operating System An operating system is the program that acts as the interface between the user (and/or application) and the hardware. It’s basically the program that controls the computer. The operating system helps simplify the task of writing applications, since the programmer does not have to be concerned with the complexities of interfacing with the hardware. The interface to the Operating System (O/S) is made simpler by providing Application Programming Interfaces (APIs) that programmers use when accessing various devices. Once a program is written using an API, it is a simple matter to move the program to a new hardware platform. Without this system software (OS), it is impossible to operate your computer as shown in the figure. Thus the purpose of operating system is to insulate the applications programmer/ user, as much as possible from the details of the particular computer complexity being used, especially memory and other hardware features such as communications and devices such as printers, keyboards, etc. Utility Software Utility programs supplement the operating system. Most operating systems include several utility programs for performing specific tasks relating to computer management. Utilities generally reside in secondary storage until summoned by the user or operating system kernel. A good example of utility is antivirus programs which prevent, detect, and remove computer viruses. A file viewer is a utility that allows you to display and copy the contents of a file. A file compression utility shrinks the size of a file. A diagnostic utility compiles technical information about a computer’s hardware and certain system software programs and then prepares a report outlining any identified problems. An uninstaller is a utility that removes an application, as well as any associated entries in the system files. A disk scanner is a utility that (1) detects and corrects both physical and logical problems on a hard disk, and (2) searches for and removes unnecessary files. A disk defragmenter is a utility that reorganizes files and unused space on a computer’s hard disk so data can be accessed more quickly and programs can run faster. A backup utility copies, or backs up, selected files or an entire hard drive onto another disk or tape. A screen saver is a utility that causes the monitor’s screen to display a moving image on a blank screen if no keyboard activity occurs for a specified period. The Startup Process for a Personal Computer (Booting) Booting is the process of starting or restarting a computer. When you turn on the computer, the power supply sends an electrical signal to devices located in the system unit. The processor chip resets itself and looks for the ROM chip that contains the BIOS (basic input/output system), which is firmware that holds the startup instructions. The BIOS executes the power-on self test (POST) to make sure hardware is connected properly and operating correctly. The POST results are compared with data in a CMOS chip on the motherboard. If the POST completes successfully, the BIOS searches for specific operating system files called system files. Once located, the boot drive (the drive from which your personal computer starts), loads the system files from storage (the hard disk – usually drive C) into memory (RAM) and executes them. Next, the kernel of the operating system loads into memory and takes control of the computer. The operating
system loads configuration information. When complete, the operating systems (Windows) desktop and icons display, and programs in the Startup folder are executed. POST (Power On Self Test) All electronic devices that are processor based, must go through an initialization when they’re first powered up. The processor when it first receives power might still have some of the data in it from the last time it was used so it must be initialized to clear out its internal buffers. When you first power-on a PC the power supply runs a self test, if good it sends a “Power Good” signal to the processor. Once the processor receives this signal it flushes out its buffers of any instructions or data and only knows one address to go to get instructions. This address points to a memory location inside the System BIOS chip. (Think of an address like a phone number the processor calls to get the first instruction) The System BIOS responds by sending instructions to the processor telling it what to do. The instructions sent to the processor make up what is referred to as the POST (Power On Self Test). POST verifies that the components needed to start the system are functioning properly. It does not test every component, only the ones absolutely necessary to successfully “Boot” the system. 4.0 COMPUTER HARDWARE Computer hardware refers to the physical parts of a computer and related devices. Internal hardware devices include motherboards, hard drives, and RAM etc. External hardware devices include monitors, keyboards, mice, printers, scanners, etc. The internal hardware parts may be referred to as components, while external hardware devices may be called peripherals. Hardware may be grouped into four major categories as shown here. Computer Storage (Memory) Computer storage, often called storage or memory, refers to computer components, devices, and recording media that retain digital data used for computing for some interval of time. Computer data storage provides one of the core functions of the modern computer, that of information retention. It is one of the fundamental components of all modern computers, and coupled with a central processing unit (CPU, a processor), implements the basic computer operation There are two kinds of computer storage/memory: primary and secondary storage/memory. Primary memory is accessible directly by the processing unit. RAM is an example of primary memory. As soon as the computer is switched off the contents of the primary memory is lost. You can store and retrieve data much faster with primary memory compared to secondary memory. Secondary memory such as floppy disks, magnetic disk, etc., is located outside the computer. Primary memory is more expensive than secondary memory. Because of this the size of primary memory is less than that of secondary memory. Computer memory is used to store two things: i) instructions to execute a program and ii) data. When the computer is doing any job, the data that have to be processed are stored in the primary memory. This data may come from an input device like keyboard or from a secondary storage device like a floppy disk. As program or the set of instructions is kept in primary memory, the computer is able to follow instantly the set of instructions. For example, when you book ticket from airline reservation counter,
Hardware
Input
Device
s
Outpu
Device t
s
Sto
r
age
De
v
ice
s
Processo
r
- The intricate dance they perform is known as the machine cycle or instruction cycle, which follows these major phases as illustrated by the figure below: 1. Fetch the instruction: prefetch unit requests instruction from memory. It is transferred from memory, via the bus, into the decoding unit. 2. Decode the instruction : decoding unit decodes the operation and operands and activates the control unit 3. Execute the instruction : the control unit sends values to the ALU to be added, subtracted, or whatever 4. Store the results : the results of the operation may be stored into memory
- The instruction cycle is repeated millions of times per second.
- It is controlled by the computers clock, which sends out timing pulses, or "ticks".
- The instruction cycle requires several clock ticks. Some instructions require more clock ticks than others.
- CPUs are usually characterized by their clock speed, measured by number of clock ticks per second. Clock speed is measured in "GHz", (Giga Hertz). 1 GHz is 1 billion clock ticks per second NOTE: If you compare 2 computers with two different clock rates, the one with the higher rate may not be "faster"! o some instructions require more clock ticks than others o if your software application uses lots of these complex instructions, it will run slower even on the same computer than some other application
- Control Unit up close and personal o major subcomponents are Instruction Register and Program Counter o a register is a very small but fast storage (32 or 64 bits) located on the CPU o the Instruction Register holds the next instruction to be carried out o the Program Counter contains the memory address where the next instruction is stored
- Cache unit is random access memory on the CPU chip itself but separate from the CPU. o Is quicker to access cache than RAM memory unit o Recently and frequently used instructions and data are stored in cache o Level 1 (L1) cache is closest to the CPU. It is fastest to access but has smallest capacity (measured in KB) o Level 2 (L2) cache is further away but still on the chip. It is slower to access but has larger capacity (possibly measured in MB) o Some chips also include Level 3 (L3) cache, measured in MB
- The CPU chip may contain two or more cores. o Each core is a processor and all can operate simultaneously o Each core will likely have its own L1 cache, but L2, L3 may be shared. o All cores share the same RAM memory unit
- You can get CPU information on a Windows XP system by selecting My Computer from the Start menu then View System Information from System Tasks. 6.0 OPERATING SYSTEMS (C’TD) Main Objectives of Operating Systems Modern Operating systems generally have following three major goals. Operating systems generally accomplish these goals by running processes in low privilege and providing service calls that invoke the operating system kernel in high-privilege state. To hide details of hardware by creating abstraction An abstraction is software that hides lower level details and provides a set of higher-level functions. An operating system transforms the physical world of devices, instructions, memory, and time into virtual world that is the result of abstractions built by the operating system. To allocate resources to processes (Manage resources) An operating system controls how processes (the active agents) may access resources (passive entities). Provide a pleasant and effective user interface The user interacts with the operating systems through the user interface and usually interested in the “look and feel” of the operating system. The most important components of the user interface are the command interpreter, the file system, on-line help, and application integration. The recent trend has been toward increasingly integrated graphical user interfaces that encompass the activities of multiple processes on networks of computers. One can therefore view operating systems from two points of view: Resource manager and Extended machine. From Resource manager point of view, operating systems manage the different parts of the system efficiently and from extended machines point of view, operating systems provide a virtual machine to users that is more convenient to use. The structurally operating systems can be designed as a monolithic system, a hierarchy of layers, a virtual machine system, or using the client-server model. The basic concepts of operating systems are processes, memory management, I/O management, the file systems, and security. Major Functions of Operating Systems An operating system has a complex mixture of diversified functions. Operating systems is the resource manager. At the simplest level, an operating system manages the hardware and software resources of the system and provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware (Abstraction) (a) User interface:-The operating system provides a convenient interface between a computer and its users. A user interface controls how you enter data and instructions and how information displays on the screen (b) Processor management::-Users submit programs or program segments to the computer for processing, requesting different processors and peripheral equipment. (c) Memory management:-A computer generally has a mixture of memory types—e.g. main memory (RAM, ROM), cache, hard disks, and flash disks--each with a different size and access time.
Other Categorization of Operating Systems Within the broad family of operating systems, there are several types of operating systems, categorized based on the types of computers they control and the sort of applications they support. The categories are: (a) Single-user, single task - As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm OS for Palm handheld computers (PDA) is a good example of a modern single-user, single-task operating system. (b) Single-user, multi-tasking - This is the type of operating system most people use on their desktop and laptop computers today. Microsoft's Windows and Apple's MacOS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time. For example, 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. (c) Multi-user, multi-tasking - A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users. Unix, VMS and mainframe operating systems, such as MVS, are examples of multi-user operating systems. (d) Real-time operating system (RTOS) - Real-time operating systems are used to control machinery, scientific instruments and industrial systems. An RTOS typically has very little userinterface capability, and no end-user utilities, since the system will be a "sealed box" when delivered for use. A very important part of an RTOS is managing the resources of the computer so that a particular operation executes in precisely the same amount of time, every time it occurs. In a complex machine, having a part move more quickly just because system resources are available may be just as catastrophic as having it not move at all because the system is busy. 7.0 DATA VERSUS INFORMATION
- Data refers to the lowest abstract or a raw input which when processed or arranged makes meaningful output. Data consists of facts and figures that are relatively meaningless to the user. It is not enough to have data (such as statistics on the economy). Data in themselves are fairly useless. In computer parlance, a spreadsheet generally starts out by holding data.
- When data are processed, organized, structured or presented in a given context so as to make them useful, they are called Information.
- Data is the computer's language. Information is our translation of this language.
- The transformation of data into information is performed by an information processor. The information processor is one of the key elements in the conceptual system. Understanding the Difference between Data and InformaƟon Data are raw numbers or other findings which, by themselves, are of limited value to decision makers. InformaƟon, on the other hand, is the result of organizing, processing, and interpreƟng data,
thus transforming the findings into facts that are useful to decision makers. For example, the number of new users your clinic serves in a month means liƩle unƟl you compare it with the number of new users from previous months and years to see whether there has been an increase or decrease in the trend over Ɵme. Data are transformed into informaƟon by:
- SelecƟon—choosing the data that are useful and adequate for answering the quesƟons that have been posed, and ignoring the data that are useless or inadequate for that purpose.
- InterpretaƟon — analyzing the data to put them into context, uncover paƩerns or problem areas, and reflect on the meaning of these paƩerns in relaƟon to the quesƟons being asked.
- The overall objecƟve of converƟng data to informaƟon is to describe, explain, predict, and/or evaluate a program and its results. DATA REPRESENTATION Computer data is made up of long sequences of ones and zeros, called bits, grouped by eight to form bytes. Actual information is represented by the bit values stored in these bytes, such as signed and unsigned integers, real numbers (fractional numbers), characters, etc. (We’ll talk about integer values here. We won’t talk about fractional (floating point numbers) representation.) Inside the computer, the steps followed are quite different from what we see on the monitor or screen. In computer’s memory both programs and data are stored in the binary form. The binary system has only two values 0 and 1. These are called bits. As human beings we all understand decimal system but the computer can only understand binary system. It is because a large number of integrated circuits inside the computer can be considered as switches, which can be made ON, or OFF. If a switch is ON it is considered 1 and if it is OFF it is 0. A number of switches in different states will give you a pattern like this: 110101....10. So the computer takes input in the form of 0 and 1 and gives output in the form 0 and 1 only. Bits The smallest "unit" of data on a binary computer is a single bit. Since a single bit is capable of representing only two different values (typically zero or one) you may get the impression that there are a very small number of items you can represent with a single bit. Not true! There are an infinite number of items you can represent with a single bit. With a single bit, you can represent any two distinct items. Examples include zero or one, true or false, on or off, male or female, and right or wrong. However, you are not limited to representing binary data types (that is, those objects which have only two distinct values).
