Chapter 3

1. Introduction to Computers Chapter 3

2. Understand how computers began and evolved into what they are today. • Identify main computer components and understand basic functions. • Be able to identify the different types of computers. • Understand computer networks and differentiate LANs, MANs, and WANs. • Identify the basic software applications needed to work on a computer. • Understand basic flowcharting and decision making. • Have a basic knowledge of several programming languages and their use. • How computers read and interpret data.

3. History of Computers • One of the first programmable devices wasthe Jacquard loom.

4. History of Computers • The history of the modern computer begins with two separate technologies—that of automated calculation and that of programmability. • Examples of early mechanical calculating devices are the abacus, the slide rule, the astrolabe and the Antikythera mechanism • Hero of Alexandria (c. 10-70 AD) built a mechanical theater which performed a play lasting ten minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when. This is the essence of programmability.

5. History of Computers Earliest Programmable Analog Computer The “castle clock,” an astronomical clock inventedby the Arabian Inventor /mechanical engineer; Al-Jazariin 1206, considered to be the earliest programmable analog computer. It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing automatic doors to open every hour, and five robotic musicians who play music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed every day in order to account for thechanging lengths of day and night throughout the year.

6. History of Computers In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard Loom was an important step in the development of computers because of the use of punched cards to define woven patterns can be viewed as an early form of programmability.

7. History of Computers In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine.” Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.

8. History of Computers • Large-scale automated data processing of punched cards was performed for the U.S. Census in 1890 by tabulating machines designed by Herman Hollerith and manufactured by Computing Tabulating Recording Corporation, which later became IBM.

9. History of Computers • By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: • Punched card • Boolean algebra • Vacuum tube (thermionic valve) • Teleprinter

10. Types of Computers • There are four main types of computers: • Supercomputers • Mainframe computers • Minicomputers • Microcomputers.

11. Types of Computers Very powerful machines, used by large corporations or organization. CRAYand IBM’s Blue Gene are considered the fastest computers in the world. Supercomputer

12. Types of Computers Capable of great processing speeds and data storage Less powerful than a supercomputer Stores and processes data centrally for the entire organization Accessed via large number of terminals Mainframe Computer

13. Types of Computers Used for a specific purpose by medium-sized companiesor departments of large corporations. You will find themused to monitor certain processes; in universities, factories or financial institutions. Minicomputer

14. Types of Computers They are the least powerful computer but also the leastexpensive and the fastest growing type, and most widely used computers. This is your PC or laptop most likely. Microcomputer

15. Types of Microcomputers • Desktop computers/Personal Computer • Designed for use at a desk or table. • Typically larger and more powerful than othertypes of personal computers. • Desktop computers are made up of separate components.

16. Types of Microcomputers • Handheld Computer • Also called PDA’s. • Small and battery powered. • Use touch screen or stylus. • Useful for appointments, addresses, phone numbers etc.

17. Types of Microcomputers • Laptop or Notebook/Netbook Computer • Lightweight mobile PCs with a thin screen. • Small and battery powered. • Unlike desktops, CPU, screen and keyboard all in one case.

18. Types of Microcomputers • Tablet PC Computers • Mobile PCs that combine features of laptops and handheld. • Small and battery powered. • Powerful and have touch screen.

19. Computer Components and Functions Input devices: Keyboard Mouse Keypad Tablet Pen

20. Computer Components and Functions Processing: Computer processing is the explanation of how information gets from the user to the computer. We input information into the computer using input devices such as the keyboard. The information is stored in temporary memory. When it leaves the temporary memory, the Processor acts as the commander and passes the instructions to the various parts of the computer.

21. Computer Components and Functions Memory: There are three types of memory; RAM, Cache, and ROM. Memory stores data, while and after it is being processed by the computer. Some memory stores the data temporarily, other types of memory stores the data permanently.

22. Computer Components and Functions Output Devices: Make the information resulting from processing available for use. The output from computers can be presented in many forms, such as a printed report or displayed on a screen. Most common are printers and monitors.

23. Computer Components and Functions Storage: Used to store instructions, data, and information when they are not being used in memory.

24. What is Inside your Computer Motherboard CPU Memory Video Card Power Supply Storage Hard disk CD or DVD Drive :

25. Multitasking/Multiprocessing In computers, it is running more than one program at the same time.  For instance, many people like to run Internet Explorer along with their word processing software Multitasking: Multiprocessing: Multiprocessing is the use of two or more Central Processing Units(CPUs) within a single computer system. Sometimes Multiprocessing refers to the execution of multiple concurrent software processes in a system as opposed to a single process at any one instant.

26. Networking and the Internet Networking is a series of computer linked and working together. In every small, medium, or large organization, there is a need for Networking. Networking means linking computer together to share resources, and information. Networking Network Types: LAN, MAN and WAN

27. Simple Flowchart A flowchart is common type of chart that represents an algorithm or process showing the steps as boxes of various kinds, and their order by connecting these with arrows. Flowcharts are used in designing or documenting a process or program in various fields.

28. How Computers Read and Interpret Data The Digital World: Computers cannot recognize information the same way humans do. We process and follow instructions based on different format; text, data, pictures, sound,…etc. If you want somebody to go right, you can simple draw an arrow pointing right, or if you want somebody to add two numbers; you could say or type, add 5 and 10. However computers cannot process such a request, they can only process digital electronic signals. So our instructions have to convert to digital electronic signals so the computers can understand and execute. Numeric RepresentationThe binary system is used to represent data and instructions; it is a two-state system; On and Off; being 1 is On, and 0 is off. Each 0 or 1 is called a bit; short for binary digit. In order to represent numbers, letters, and special characters, bits are combined into groups of eight bits called bytes. Each byte can store one letter or one digit. So when you enter a number into a computer system, the number has to be converted into a binary number before the computer can process it. However, binary numbers are hard to work with because they require so many digits, so are often represented in a format more readable by humans. The hexadecimal systemor hex, uses 16 digits (0,1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F)to represent binary numbers. One hex digit represents four binary digits, and two hex digits are commonly used together to represent 1 byte (8 binary digits).

29. End of Chapter Chapter Three Complete