1. T171 Learning and Living in the Environment Age Presented By: Magda Attia

2. Office hours: Even weeks Tuesday: 3-4 PM – 8-9 PM Wednesday 8 – 9 AM, 1-2 PM Phone Calls 4 - 6 pm (Sat. To Wednesday) Mobile 0504685875 How to contact your tutor:

3. Learning materials The T171 web site http://arabweb1.open.ac.uk/t171 username : t171mar password : buttercups Moodle, AOU, LMS references Accidental Empires book by Robert Cringely. Computer Concepts book by Parsons/OJA.

4. T171 web site

5. Module 1:Your computer: the story of the PC Module 1 is built around a set book, Accidental Empires. About Module 1 Section 1 Background material Section 2 Intel and the microprocessor Section 3 The start of the PC industry Section 4 Xerox PARC Section 5 IBM and the PC Section 6 IBM clones Section 7 Apple and the Mac Section 8 Windows OS/2 and networking Section 9 Conclusions

6. Module 1 Objectives - Give a coherent and informed account of the development of the personal computer. - Identify the key people, organizations and technologies who have played a part in the development of the personal computer. - Explain the basic architecture of a computer and the functions of its main hardware and software components. - Understand the key business concepts specific to the PC industry.

7. Microcomputers This module is emphatically about the microcomputer industry, and not the computer industry in general. large computers, called mainframes, were the dominant means of computing before the invention of the microcomputer. Microcomputers are so-called because they use a microprocessor for their computation. They are often referred to as personal computers (PCs).

8. Microcomputers three themes form the basis of the industry, and this module. They are: companies, personalities and technology. the companies can go out of business, the personalities can change companies, and the technology can become obsolete.

9. Computer parts and components When you think of a computer you probably think of the dull-looking box sitting on top of, or underneath, your desk, plus the monitor, keyboard and mouse. These, along with all of the components inside the computer box, are the physical parts of the computer - the hardware. But the hardware is just an expensive doorstop without something to make it work. For you to produce your annual budget, write your great novel, you need programs which will make the computer do things. The computer also requires programs just to look after itself and to manage all its components. Programs are the software. since the computer requires both to be a functional machine. You might like to think of the hardware as a car, and the software as the driver and the fuel it requires before it can be driven. Computer (Technology) = HW + SW

10. Hardware Hardware includes components such as the microprocessor, hard disk drive, memory chip, graphics card and so forth. Separate hardware items that are added onto the basic computer unit, such as the monitor, modem, printer, keyboard, etc., are often called peripherals.

11. Software Software can be written in a variety of programming languages. A programming language is used to express the instructions which tell the computer what to do in response to a certain action. For instance, word processing software tells the computer to display the letter 'a' on the monitor when you press the 'a' key on your keyboard. Software can be divided into three basic categories: 1.Operating systems. These communicate with the hardware of the machine, and act as the basis on which other software programs can be run. The operating system, or OS, is the means by which both other programs and the user interact with the computer. It is the first thing you see when your computer starts up, and it allows you to tell the computer what it is you want to do. Examples of operating systems include DOS, Windows, UNIX and the Macintosh OS. 2.Languages. These allow developers to write new software programs. There is a wide range of programming languages to suit different types of task; examples include Basic, C, Assembler, Pascal, C++, Visual Basic and Java. 3. Applications. These allow you to perform activities to which the computer is suited. Applications are the reason most people buy computers in the first place. Examples include word processors (such as Microsoft Word), spreadsheets (e.g. Lotus 1-2-3), databases (e.g. Access), graphics packages (e.g. Corel DRAW).

12. Binary System how a computer represents information At its very lowest level a computer operates by turning on or off millions of tiny switches, called transistors. transistors can only be in one of two states; that is, on or off. Such devices are thus referred to as two-state devices. The states of 'on' and 'off' can be represented by the numbers 1 and 0. In mathematics the term binary is used to refer to a number system which has only two digits, that is 1 and 0. The number system we use in everyday life has ten digits, 0 to 9, and is called denary. The binary system is the smallest number system that can be used to provide information. Any number from denary system can be represented in binary; 0 in denary is 0 in binary. Similarly 1 in denary is 1 in binary. When you get to 2 in denary you have a problem. There are no more symbols in binary; you are restricted to only 1 and 0. So how do you represent two? This question is similar to asking how you represent ten in denary. Once you get to nine you have run out of digits, so you simply create a new column and start afresh, using 1 and 0. This is also what you do in binary, so 2 in denary becomes 10 in binary. When you move on to 3 (in denary) you proceed as before; 3 becomes 11 in binary.

13. Denary numbers Vs Binary

14. Representing Letters & Instructions there is an agreed representation of text known as International Alphabet Number 5 (IA-5) in which the letter 'A' is represented by the binary pattern 1000001. The same pattern could be used to represent the denary number 65. The computer knows what to do with the data because it has instructions from a program, and these instructions are themselves binary representations.

15. Representing Data and Instructions It is worth examining the difference between data and instructions. The data is the current information the computer program is working with. This might be some numbers I am adding up, or some text I am typing. It will vary from instance to instance. The instructions are what the computer does with the data. This must always be consistent, for example clicking on the Save button will always save the data.

16. Representing Data and Instructions So numbers and text can be represented using the binary system. What else can? Images can be represented using a technique known as bit-mapping. This divides an image up into thousands of cells and allocates a value to each cell. If the image is in black and white, each cell will have a value of 1 (indicating it is black) or 0 (indicating it is white). Colour can be represented by allocating more information to each cell to indicate the proportion of red, green and blue (RGB) values. A wide spectrum of colours can be created by varying the relative values of red, green and blue. What else can be represented in binary? The answer is just about anything. Sound, like images, can be divided up into different segments and each given an appropriate binary value, which can then faithfully reproduce the sound. This is what your music CD player does.

17. Analog Vs Digital Analogous defined as partially similar or parallel uses 'physical variables', which include length, weight and voltage Analogue quantities are found commonly in nature Analogue signals Continuous Take any value within their limits (a specified range ) Digital Operating on data represented as a series of binary digits uses digits Digital signals Discrete, which means separate or distinct. Take set values within their range.

18. What Are The Benefits of Being Digital? Digital are often faster and more efficient than analogue equivalents. There are two reasons digital systems are superior: Reliability and Manipulation

19. Bits and bytes So computers work by manipulating 1s and 0s. These are binary digits, or bits. Single bits are too small to be much use, so they are grouped together into units of 8 bits. Each 8-bit unit is called a byte. A byte is the basic unit which is passed around the computer, often in groups. Because of this the number 8 and its multiples have become important in computing. Bits, bytes, kilobytes and megabytes are merely ways of measuring the size of things computers deal with. A kilobyte is 2 to the power of 10 bytes. This is actually 1024 bytes, but is close enough to a thousand to be given the prefix kilo, meaning a thousand. Similarly, a megabyte is 2 to the power of 20 (or 1 kilobyte squared), which comes out as 1,048,576 bytes. For the sake of convenience, this is called a megabyte, meaning a million bytes. A gigabyte is 1000(1-24) megabytes (billion bytes).

20. Data & Storage Measurements 1Byte=8Bit 1Kilobyte=1024(1000)Bytes 1Megabyte=1024KB=1048576(million)Bytes 1 Gigabyte = 1024 Megabyte=1073741824 =(Billion) Bytes

21. ***Computer architecture Manipulating data how a computer uses this binary representation to perform its various tasks? By combining a series of bytes any data or instruction can be represented. Consider a simple example which takes a number and displays it on the screen. The following instructions might operate for this program: 10000000 = start program 00000001 = exit program 00000011 = consider next byte as a number 00000101 = display previous number Although computers operate by manipulating 1s and 0s, this is not a very useful way for people to work. A more productive means of telling the computer what to do is required. This need led to the development of programming languages. The first of these was known as Assembler, which operates at quite a low level in the computer, telling the computer where to move data and what to do with it. Assembler takes commands and converts them in to 1s and 0s, which the computer can interpret. In the dummy program above we used a byte (eight bits) to represent each 'chunk' of information. aaa

22. The components of a computer The key to your computer is a chip called the microprocessor. This is its brains, and is where most of the computing takes place. Before the advent of the microprocessor, computers came mainly in the form of large mainframes which had a different circuit board for each function. At the core of a mainframe computer are three separate units linked together to form what is known as the central processing unit, or CPU. These three units are: 1.The arithmetic and logic unit (ALU) - this is the unit which does the actual work of the computer. As well as the four basic maths functions of addition, subtraction, multiplication and division, it has comparison capabilities such as =, >, < (equals, more than, less than). 2.The control unit (CU)- this unit controls the flow of data from the computer's memory into the ALU and to other devices. 3. The Memory.

23. Microprocessor A microprocessor combines the ALU and control unit on one silicon chip, which is why it was at one time referred to as the 'computer on a chip'. In mainframes the CPU includes memory, but this is separate in microcomputers, so I shall use the term CPU to refer to just the combination of ALU and control unit. in addition to the microprocessor which forms the CPU there are other microprocessors that are used to control the graphics card, modem and other devices. The CPU microprocessor is housed on a circuit board called the motherboard. Also on the motherboard is the clock chip which acts as a metronome for the computer so that all its actions can be synchronized. There may also be one or two ROM chips. ROM stands for Read Only Memory, which means that the data on these chips cannot be altered, it can only be read. These chips often contain some important programs which come supplied with the computer and which are needed for it to function properly. This is why they are made to be read-only; it would be very unfortunate if an unsuspecting user altered them.

25. As well as the CPU microprocessor there are devices which can be used to enter data into the computer, and which it can use to output data. These are called input/output devices (usually referred to as I/O devices ) and might include a keyboard and mouse (for input) and a monitor and printer (for output). The data for these devices will often pass via a slot-in circuit board (called a card) inside the PC which plugs into a slot on the motherboard. The CPU also sends and receives data to and from the computer's memory, which is usually referred to as RAM (random access memory). The RAM consists of chips similar in construction to the CPU. This is the memory which stores all the data the computer is currently using. The contents of RAM are often lost when the computer is switched off. Computer Components

26. MEMORY (READ ONLY MEMORY) -BASIC OS -CANNOT BE CHANGED -ENABLES COMP. TO COMPLETE SMALL JOBS -PLACING A CHARACTER ON SCREEN -CHECKING KB TO SEE IF A KEEY IS PRESSED. RANDOM ACCESS MEMORY MAIN MEMORY -STORES DATA AND INSTRUCTIONS -TEMPORARILY -DATA CAN BE MODIFIED -WHEN PC IS TURNED ON IT IS EMPTY -IF PC IS OFF, THEN DATA ARE LOST. -WORKS LIKE DESKTOP (ANY PROGRAM NEEDS TO BE EXECUTED MUST E FIRSTMOVED TO THE RAM ROMRAM

27. More in Computer Components The microprocessor will also have to read from and write to a permanent data storage device in the form of a hard disk drive. Other permanent storage devices include CD-ROMs (again the ROM in the name indicates that these CDs cannot be written to), optical disks, tape storage or floppy disks (which may be read only or writable). To receive and send all of this data the microprocessor is connected to cables, which are referred to as buses. Buses are designed to carry all kinds of data, rather like the buses you might use to travel around a city.

28. Computer Architecture

29. factors that affect computer power 4 factors that affect the computer power: 1.The first factor is the microprocessor chip used for the CPU. Successive generations of chips have more and more transistors placed on them. With more transistors available the chip can be programmed to perform more tasks, thus increasing its complexity. The new computer had an Intel Pentium microprocessor, which has approximately 3.1 million transistors.

30. Increased numbers of transistors also allow the chip manufacturers to implement new methods of improving memory usage and speed of performance. For example, earlier versions of the Intel microprocessors required a seperate chip to be installed in order to cope with any software requiring lots of calculations involving floating point numbers. The extra chip, known as a maths co-processor, was integrated in the main microprocesor as more transistors were made available in subsequent versions. More transistors means faster Processor. factors that affect computer power

31. 2. Clock speed The second factor that determines a computer's power is its clock speed. Each action of the CPU can be thought of as occupying one cycle. Therefore the greater the number of cycles per second, the faster the computer. Back in 1997, my older machine had a clock speed of 66 MHz (1 megahertz means one million cycles per second), whilst the new one had a clock speed of 133 MHz. The new computer roughly doubled the performance of the old one. In one second my new computer was able to perform roughly twice the number of functions that its predecessor could. factors that affect computer power

32. 3. Word size The third factor is the size of the words which both the microprocessor and the buses can accommodate. You may sometimes hear people refer to a computer (or particularly a games console) as a '32-bit', '64-bit' or '128-bit' machine. These terms refer to the size of word that the microprocessor can manipulate. The larger the word size, the more information each word can contain. factors that affect computer power

33. 4. Memory A fourth factor that affects a computer's power is the amount of memory, or RAM, available. RAM acts as the computer's working memory, so it contains the information the computer needs for its current session. This will include various operating system commands, the programs currently running (e.g. Microsoft Word with two documents open), and so forth. An increase in the size of the RAM increases the amount of data it can store at any one time. This improves the complexity of the computer because it can run programs which require a lot of data to be handled, and several programs can be run simultaneously. It also increases the speed of the computer because when the RAM becomes full the computer will temporarily store data on the hard disk. This will be retrieved when it is required, which takes more time than having it currently available in memory. So more RAM provides more speed. factors that affect computer power

34. Computer Types Mainframes were the dominant form of computing before microcomputers. They are usually very expensive, powerful and operate specialist software. Mainframes are typically used by large companies, public authorities and universities for their data handling tasks. These tasks are typically: 1. File maintenance: Maintaining records is a huge task for institutions. Records can contain information on sales, credit card status, payroll details, health records, stock inventory, etc. These either need to be accessed by different people in real-time (for instance a travel agent booking an airline ticket) or updated in batches (for instance warehouse stock levels at the end of each day). It is necessary in such cases to have the data stored centrally and then accessible by those who need it. A lot of minicomputers are now capable of performing these tasks in medium-sized companies.

35. Mainframes 2. Simulations: Many physical and engineering problems cannot be solved without the help of complex computer simulations. These require intensive mathematical work, and so take advantage of a mainframe's computational power. Examples include weather forecasting. Many minicomputers or workstations are now used for this type of problem. 3. General purpose: Many universities used a mainframe to act as a general purpose computing facility. They are particularly useful when data needs to be held centrally, with different people needing access to it. This is illustrated below:

36. Mainframes

37. Minicomputers Minicomputers are powerful, special-purpose computers. They were originally viewed as small mainframes - hence the prefix 'mini'. However, they have become increasingly powerful and have replaced mainframes for many functions. Examples include Digital Equipment's VAX machines and IBM's AS/400s. Tasks minicomputers might be used for include: 1. Plant control: Many industrial plants require a central computing facility to collect data from various sensors and then to act accordingly. 2. 2. Network control: Many computer networks need a central computer which provides storage space and controls the network using special network software. This is known as a server. The other computers which access the server are called clients. Such machines can also act as the interface to the Internet. Powerful PCs can also be used to perform these functions. 3. Databases: As mentioned above, the role of mainframes in file maintenance is increasingly being taken by minicomputers. Minicomputers can hold databases of records which appropriate people can access. 4. For the general public it is PCs which tend to symbolize computers. However, most 'heavy duty' computing is performed not by PCs but by minicomputers. With the growth in networking computers in most institutions the role of minicomputers has grown. It is in this market that some of the largest software companies, such as Novell who provide networking software and Oracle who supply database software, do most of their business.

38. Minicomputers

39. Workstations Workstations are based on specialized microprocessors and can be thought of as powerful PCs. They are typically used for specialist engineering tasks. Workstations use a special type of microprocessor known as a RISC chip (Reduced Instruction Set Computing). This technology, developed at IBM, removes many of the complex instructions from a microprocessor and has instead a set of basic instructions, which perform their tasks very quickly. This approach increases the speed and the power of the microprocessor, particularly when dealing with numerical problems. The workstation market is dominated by SUN Microsystems. Tasks workstations might be used for include: 1. CAD/CAM: Computer Aided Design and Computer Aided Manufacturing have been growth industries since the mid-1980s. These technologies allow engineers to design complex machine parts without having to produce an actual physical model. The necessary complex, 3-D graphics require a lot of computing power and good quality video capabilities. 2. Animation: Similarly to CAD/CAM, animations require a lot of processing power which must be performed quickly, and are ideally suited to the RISC technology. 3. Simulations: Performing simulations of processes, such as the behaviour of an industrial plant, requires considerable computing power. Multitask programming: Any complex programming which is deemed to require more power than is offered by a PC, and which needs to perform more than one task at a time (called multi- tasking), is often performed on a workstation. Recent PC operating systems such as Windows NT can also perform multi-tasking.

40. Microcomputers (Personal Computers Microcomputers are based on a microprocessor and are intended for individual use; hence they are called personal computers, or PCs. They were initially stand-alone machines, but are increasingly connected to a network. They are ideal for tasks such as those listed below where the user requires individual computing power. 1. Word processing: Word processing programs allow a user to produce professional-looking documents, with different fonts, styles and pictures. The production of complex and attractive documents is much easier with the use of word processing software than it was in the days of the typewriter. 2. Spreadsheets: Spreadsheets allow a user to create mathematical models. These are particularly useful in financial planning and can be used to answer questions such as 'What happens if we raise the cost of our product by 1%?'. 3. Desktop publishing: This allows people to create drawings, manipulate images and combine them with text to produce professional graphic design work, for instance magazine layouts, posters, book covers, etc. 4. Games: Although this may seem a non-serious use of computers, games represent a large market. By making use of the PC's computing power very good quality graphics and complex game play can be achieved. 5. Servers: As mentioned above, many powerful PCs are now being used as servers to control a network.

41. Generally the tasks performed by the mainframes have been taken over by minicomputers. PCs initially created a new type of usage for the computer; for instance, spreadsheets and desktop publishing took over from activities previously performed by hand. As PCs have increased in power they have begun to be used for some of the tasks that required minicomputers and even mainframes in the past. With the increase in computer power the distinction between types of computers is often difficult to maintain. When does a PC become a workstation for instance? Remember, though, that having an appreciation of the different types of computers and the tasks required of them is important, but you should not get too bogged down in trying to categorize machines. Microcomputers (Personal Computers

42. Summary on Computer Types Computers are generally divided into three major types, these are: Mainframe computers. These are large and expensive computers used by major companies and universities to perform various tasks such as file maintenance, simulations and other general-purpose uses. Minicomputers. These are powerful special purpose computers that could be used for plant control, network control, database servers and workstations. Personal computers. These are based on microprocessors and intended for individual use, hence the word personal computer or PC. This is the type that we will be mainly concerned with in this course. They have many uses such as desktop publishing, spreadsheets, games, With the increase of computer power the distinction between these types is often difficult to maintain.

43. Quick review and suggested readings: The table below summarizes the items learned in this section along with suggested reading from the set book “ Computer Concepts ” by Parsons and Oja.

44. Homework Study section 1 from the course site Read TMA1