1. Introduction to Computers From Chapters 1 & 2, Computers- Understanding Technology 1Bill Pegram - August 30, 2009

2. What is a Computer Operates under control of a set of instructions, that is stored in its memory Accepts data from a user Manipulates the data according to the programmed instructions Produces the results Stores the results for future use Bill Pegram - August 30, 20092

3. Special-Purpose vs. General- Purpose Computers Special-purpose, or embedded computers, perform a few specific actions whereas general purpose computers can perform a wide range of actions Examples of special purpose computers would include chips in digital thermometer, microwave oven, digital camera, car Bill Pegram - August 30, 20093

4. Terminology Digital (0 vs. 1, on vs. off) vs. analog (pulses in continuous wave) Microcomputer or personal computer (intended to be operated by a single user) 4Bill Pegram - August 30, 2009

5. Information Processing Cycle Input Processing Output Storage 5Bill Pegram - August 30, 2009

6. Computer System Hardware Components Motherboard - Central Processing Unit (CPU) (Chapter 2) and Memory (Chapter 2) Input Devices (Chapter 2) Output Devices (Chapter 3) Storage Devices (Chapter 3) Communications Devices 6Bill Pegram - August 30, 2009

7. Software System software (Chapter 4) - Operating system (e.g. Windows, MacIntosh) Utility software (e.g. file backup, virus protection) Application software (Chapter 5) – Office software, browsers, etc. Communications software 7Bill Pegram - August 30, 2009

8. Categories of Computers (p. 23) Personal computers Handheld computers Workstation Midrange server Large server or mainframe computer Supercomputer 8Bill Pegram - August 30, 2009

9. History of Computers Timeline Pages TI-A1-A14 following first chapter 9Bill Pegram - August 30, 2009

10. Input Devices Keyboard – alphanumeric & special function (some at fast food restaurant but touch screens increasing used) Touch screen – ATMs, airport checkin counters, kiosks, restaurant cashier, grocery store self-service checkout (e.g. Giant, Harris Teeter), VA DMV Written Test for Driver’s license, Apple iPhone, Windows 7 (successor to Vista) Mouse Trackball – plastic sphere resting on rollers, often used in laptop computers Touchpads – you move the pointer by sliding your finger across the surface of the pad 10Bill Pegram - August 30, 2009

11. Input Devices Operating systems such as Windows and Macintosh employ a graphical user interface (GUI – pronounced gooey) in which the user issues command by using a mouse to make selections With DOS (the previous operating system for IBM-compatible computers), users issued commands through typing on a keyboard 11Bill Pegram - August 30, 2009

12. Mouse Technology Mouse has used a rubber-coated ball on the bottom of the mouse; movement of the mouse on a surface results in rotation of the ball which is recorded by sensors in the mouse An optical mouse uses a light sensor instead of a ball to track movement 12Bill Pegram - August 30, 2009

13. Input Devices (cont.) Microphone (audio input) Joystick – computer games Graphics tablet and pen Optical scanner Bar code readers, magnetic card readers Digital cameras 13Bill Pegram - August 30, 2009

14. Input Devices (cont.) Digital video cameras – including retinal and thumb print scanners (e.g. preferred travellers at airports, thumb print scanners at tanning salons to prevent multiple visits within 24 hours) Nintendo Wii Remote and Platform 14Bill Pegram - August 30, 2009

15. Computer Representation of Data Bit (either 0 or 1) Byte - 8 bits ASCII (7 bit encoding) – PC’s EBCDIC (8 bit encoding) – large computers Unicode (16 bit) – used in newer operating systems such as Windows Vista and Macintosh OS X 15Bill Pegram - August 30, 2009

16. System Unit Power supply – converts from AC into DC and fan Bay or Storage bay – site where storage device can be installed Motherboard – thin sheet which has a number of components connected to it (see next slide) 16Bill Pegram - August 30, 2009

17. Motherboard –CPU –System clock and battery –Slots for RAM chips –One or more read-only memory chips –Expansion slots –Ports for connecting input and output devices –Buses, which allow communication between components in the computer Bill Pegram - August 30, 200917

18. Bays A bay is a site where a device such as a floppy disk drive or hard drive is installed An internal bay is concealed entirely within the computer case An exposed bay has an opening to the outside of a computer case 18Bill Pegram - August 30, 2009

19. Bays (cont.) The availability of empty bays used to be an important constraint on expanding the capabilities of a computer; much less important now due to the ability to connect external devices through USB ports (see later) Bill Pegram - August 30, 200919

20. Central Processing Unit Control unit – interprets program instructions and initiates action to carry them out – fetch and decode portion of machine or instruction cycle Arithmetic/logic unit (ALU) – execute part of cycle Registers – temporary storage locations that can be accessed much faster than locations outside of the CPU; instruction registers, data registers, storage registers 20Bill Pegram - August 30, 2009

21. CPU (cont.) System clock – generates pulses which synchronize activity within computer Clock speed is measured in hertz (pulses per second) – megahertz (MHz) (1 million/sec) and gigahertz (GHz) (1 billion/second) – chart p. 73 One clock cycle equal to 2 clock ticks Coprocessors – math, graphics, cryptographic 21Bill Pegram - August 30, 2009

22. Key Advances in Microprocessors Reduced instruction set computing (RISC) Pipelining – computer can begin executing another instruction as soon as previous instruction reaches next phase of machine cycle Closer circuits Better materials Parallel processing 22Bill Pegram - August 30, 2009

23. Key Advances in Microprocessors (cont.) Multithreading and hyperthreading – allows parallel processing Dual-core and multi-core processors 23Bill Pegram - August 30, 2009

24. Memory Random access memory (RAM) – each memory location has its own address so CPU can go directly to the instructions and data it needs Random access memory is reusable (new data or instructions can replace what was formerly there) Random access memory is volatile memory; only retains information while power is on 24Bill Pegram - August 30, 2009

25. Cache Memory Cache memory contains data and instructions recently used by processor; when CPU looks for data or instructions, it first looks in the cache Because there is often repeat use of data or instructions, this decreases time required to get the information A browser cache for images speeds up web surfing 25Bill Pegram - August 30, 2009

26. Read-only Memory (ROM) ROM contains instructions or data permanently there; does not depend on maintaining continuous power ROM contains BIOS (basic input/output system) program which is the program that boots or starts the computer when it is turned on 26Bill Pegram - August 30, 2009

27. Flash Memory Nonvolatile memory that can be erased and reused Used in many handheld computers and devices including flash drives (thumbnail drives) – significant increase in size and decrease in cost in last couple years 27Bill Pegram - August 30, 2009

28. Expansion and Ports Expansion boards – sound, video, graphics, modem, etc. Ports – external plug-in slot –serial or communications (COM) (one bit at a time) –Parallel (LPT)– traditionally used to connect printer –Video – connect monitor –USB (Universal Serial Bus) – can be used to connect many type of devices 28Bill Pegram - August 30, 2009

29. Buses A bus is a pathway within a computer along which bits are transmitted Bus width refers to number of bits that can be transmitted at one time; e.g. 32-bit bus Expansion bus – interacts with RAM and low-speed devices Local bus – high speed peripherals and connects directly to CPU 29Bill Pegram - August 30, 2009