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Hardware: Input, Processing, and Output Devices Chapter 3.

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Presentation on theme: "Hardware: Input, Processing, and Output Devices Chapter 3."— Presentation transcript:

1 Hardware: Input, Processing, and Output Devices Chapter 3

2 Chapter Topics Computer system components The power, speed, and capacity of processing and main memory devices. Access methods, capacity and portability of secondary storage devices. Input & output devices The popular classes of computer systems

3 Hardware: Typical System Printer (output)Monitor (output) Speakers (output) Mouse (input) Keyboard (input) System unit (processing and secondary storage)

4 Computer Hardware CPU Memory System Unit Input Devices Storage Devices Output Devices Peripherals Ports Motherboard Expansion Slots

5 On the Motherboard A motherboard CPU Expansion slots A firewire card Pins to attach to The motherboard A RAM chip

6 CPU FetchDecode ExecuteWrite-back Memory Registers ALU Control Unit

7 CPU Control Unit Maintains order Controls CPU activity Directs sequence of operations Arithmetic/logic Unit (ALU) Manipulates data Performs arithmetic computations Performs logical operations Registers Temporary storage areas for instructions or data offer the advantage of speed work under the direction of the control unit to accept, hold, and transfer instructions or data

8 Machine Cycle FetchDecode Execute Instruction Cycle Execution Cycle Write-back

9 Machine Cycle Time Measures Microseconds (1 millionth) Nanoseconds (1 billionth) Picoseconds (1 trillionth) MIPS (Millions of Instructions Processed per Second)

10 How fast is a Nanosecond? If one nanosecond is.. One mile One person One minute One square mile Then one second is equivalent to … 2000 trips to the moon and back Population of China and the U.S years 17 times the land are of the world

11 Data Bus FetchDecode ExecuteWrite-back Word sizes 8 bits 16 bits 32 bits 64 bits

12 Processing Characteristics Clock speed: electronic pulses affecting machine cycle time –Hertz: one cycle (pulse) per second –Megahertz (MHz): millions of cycles per second Microcode: internal, predefined elementary operations in a CPU

13 Microcode Instruction Sets Complex instruction set computing: CPU contains many microcode instructions Reduced instruction set computing (RISC): Minimal set of microcode instructions Very Long Instruction Word (VLIW): Each microcode instruction is longer and does more.

14 Multiprocessing More than one CPU is present –Tasks are divided among CPUs in true parallel processing Parallel processing uses multiple processors to execute instructions in concert.

15 Parallel Processing Control CPU Combined Results

16 Physical Characteristics of the CPU Digital circuits on chips Electrical current flows through silicon Moores Law states that transistor density of chips will double every 18 months

17 Memory Characteristics and Functions

18 Memories Random Access Memory (RAM) CPU Primary Cache Secondary Cache System Bus External Storage Devices Expansion slots I/O Bus ROM

19 ROM Chip and BIOS ROM stands for Read Only Memory ROM is a non-volatile memory on a chip The ROM chip contains Basic input/output system BIOS The BIOS has the instructions necessary to start up your computer

20 RAM RAM stands for Random Access Memory RAM is a volatile memory on a chip RAM chips store information in addresses that can be accessed directly and quickly

21 Storage Media Storage devices retain data when power is switched off Storage devices are slower than memory devices like RAM

22 Memory Versus Storage Memory –A temporary holding place for data and instructions –Consists of one or more chips on the motherboard –Sometimes called primary storage Storage –The media on which data, instructions, and information are kept, as well as the devices that record and retrieve these items –Storage also called secondary storage, auxiliary storage, permanent storage, or mass storage –Storage is nonvolatile

23 Managing Memory Remember the Machine Cycle? Page is swapped in Decoding and Execution Page is swapped out

24 2. OS kernel, or supervisor program becomes memory resident. 3. CPU reads and executes instructions Starting Up 1.BIOS read from ROM

25 Storage Capacity The number of bytes (characters) a storage medium can hold Manufacturers use many terms to define the capacity of storage media Storage Term Abbreviation Number of bytes Kilobyte Megabyte Gigabyte Terabyte Petabyte KB MB TB GB PB 1 thousand 1 million 1 billion 1 trillion 1 quadrillion

26 Data Representation A computer circuit represents the 0 or the 1 electronically by the presence or absence of an electronic charge. Binary Digit (Bit): Electronic State 1 On 0 Off Binary system: two unique digits, 0 and 1 Bit: the smallest unit of data the computer can represent A byte: a group of 8 bits: represents a single character in the computer

27 Bits and Bytes Byte Eight bits Kilobyte - 1 thousand bytes Megabyte - 1 million bytes Gigabyte - 1 billion bytes Terabyte - 1 trillion bytes

28 Coding Schemes A byte provides enough different combinations of 0s and 1s to represent 256 individual characters. A coding scheme: the defined combinations of 0s and 1s that represent characters by patterns –ASCII(The American Standard Code for Information Interchange) ASCII represents 0-9, upper and lower case A-Z, and English language punctuation in byte code –EBCDIC (The Extended Binary Coded Decimal Interchange Code) –Unicode

29 Data Storage Hierarchy Bits Character (byte) Field Record D O G DOG, FOUR LEGS, TWO EARS File DOG….. CAT…. FOX….

30 Storage Modes Direct(Random) Access –records can be retrieved in any order –Faster (nanoseconds) –Usually more expensive Sequential –records must be retrieved in order –Slower (milliseconds) –Less expensive The dog barked. THEDOG..THEDOG.. Th e d og bar k ed

31 Sequential access versus Direct access Sequential access –Method used for tape –Reading and writing data consecutively –You must forward or rewind the tape to a specific point to access a specific piece of data –Much slower –Utilized most often for long- term storage and backup Direct access –Method used for floppy disks, hard disks, and compact discs –Also called random access – You can locate a particular data item or file immediately, without having to move consecutively through items stored in front of the desired data item or file –Faster –Used as the primary method of storage

32 Storage Technologies Magnetic –Read/write head uses electrical impulses to create or interpret patterns of magnetic impulses Floppy disks Hard disks Tape Optical –Laser beam creates or reads non-reflective pits and reflective land areas CDs DVDs Ancient DecTape systems

33 Disks Sector Cluster Read/Write Head

34 Access time The amount of time it takes the device to locate an item on a disk Defines the speed of a disk storage device Memory (RAM) Compact Disc Floppy Disk Tape Hard Disk cost less expensive more expensive speed faster slower

35 CD-R & CD-RW CD-R (compact disc- recordable) You write on the CD-R using a CD recorder or a CD-R drive and special software The CD-R drive can read and write both audio CDs and standard CD-ROMs You cannot erase the discs contents Most CD-ROM drives can read a CD-R CD-RW (compact disc- rewritable) An erasable disc you can write on multiple times You must have CD-RW software and a CD-RW drive

36 DVD-ROM (digital video disc- ROM) An extremely high capacity compact disc capable of storing from 4.7 GB to 17 GB You must have a DVD-ROM drive or DVD player to read a DVD-ROM Looks just like a CD-ROM but data, instructions, and information is stored in a slightly different manner to achieve a higher storage capacity

37 Magnetic Tapes A magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost A tape drive reads from and writes data and information on a tape Older computers used reel-to-reel tape drives A tape cartridge is a small, rectangular, plastic housing for tape used in todays tape drives Used by business and home users to backup personal computer hard disks Both external and internal tape units for personal computers Larger computers use tape cartridges mounted in a separate cabinet called a tape library

38 Storage techniques used in an enterprise system Storage area network (SAN): A high-speed network that connects storage devices Tape library: A high-capacity tape system that works with multiple tape cartridges for storing backups of data, information, and instructions RAID system: Ensures that data is not lost if one drive fails Server: Stores data, information, and instructions need by users on the network CD-ROM jukebox: Holds hundreds of CD-ROMs that can contain application programs and data. Also called a CD-ROM server Internet backup: Stores data, information, and instructions on the Web

39 RAID Redundant array of independent disks A type of hard disk system that connects several smaller disks into a single unit that acts like a single large hard disk More reliable than a traditional disk system but quite expensive RAID duplicates data, instructions, and information to improve data reliability

40 How does RAID work? Mirroring (RAID Level 1) Striping Level 1, called mirroring, has one backup disk for each disk Levels beyond level 1 use a technique called striping, which splits data, instructions, and information across multiple disks in the array

41 Additional Devices and Media Memory Cards –A thin, credit card-sized device –Fits into a PC Card slot on a notebook other personal computer –Different types and sizes add storage, additional memory, communications, and sound capabilities to a computer –Three types of PC Card –Advantage of a PC Card for storage is portability between systems Flash memory –Also called flash ROM or flash RAM –Nonvolatile memory that can be erased electronically and reprogrammed –Stores data and programs on many handheld computers and devices –Flash memory cards store flash memory on removable devices instead of chips

42 Input and Output Interrupts Device Driver software

43 Input devices What is input? –Any data or instructions you enter into the memory of the computer –Users can input data and instructions in a variety of ways Types of input –Data: A collection of raw unprocessed facts, figures, and symbols –Instructions: Programs, Commands, User responses

44 Data Data can be human or machine readable Data entry converts human readable data into machine-readable form Data input transfers machine-readable data into the system Source data automation

45 Input Devices Personal computer input devices –Keyboard –Mouse Voice-recognition devices Digital cameras Terminals

46 Input Devices Scanning devices Optical data readers Bar code scanners MICR devices POS (point-of-sale) devices Pen input devices Light pens Touch screens

47 Output Devices Monitors –Cathode Ray Tubes (CRTs) –Liquid Crystal Displays (LCDs) Active matrix Passive matrix Printers Plotters Computer Output Microform (COM) Music Devices

48 Contains a cathode ray tube (CRT), a large sealed, glass screen The screen is coated with tiny dots of phosphor material A pixel, or picture element, is a single point in an electronic image Three dots (red, blue, and green) combine to make up each pixel What is a CRT monitor? CRT monitor screen cathode ray tube

49 What is a liquid crystal display (LCD) monitor? A type of flat-panel display Uses liquid crystals between two sheets of material to present information on a screen An electric current passes through the crystals which creates the images on the screen

50 800 x 600 typically the standard What is display resolution? Describes the sharpness and clearness of an image Resolution of a display device stated as dots, or pixels 1280 x 1024 maximum resolution of most monitors 800 horizontal pixels 600 vertical pixels Total of 480,000 pixels on screen 2048 x 1536 maximum for high-end monitors

51 What is a video card? Converts digital output from the computer into an analog video signal Sends the signal through a cable to the monitor Controls how the display device produces the picture Also called a graphics card or video adapter

52 How does video travel from the processor to a CRT monitor? Step 1: The processor sends digital video data to the video card. Step 2: The video cards digital-to-analog converter (DAC) converts the digital video data to an analog signal. Step 3: The analog signal is sent through a cable to the CRT monitor. Step 4: The CRT monitor separates the analog signal into red, green, and blue signals. Step 5: Electron guns fire the three color signals to the front of the CRT. Step 6: An image displays on the screen when the electrons hit phosphor dots on the back of the screen.

53 24-bit video card Uses 24 bits to store information about each pixel Can display 16.7 million colors 2 24 = 16.7 million colors What is bit depth? The number of bits a video card uses to store information about each pixel Also called the color depth Determines the number of colors a video card can display The greater the number of bits, the better the resulting image 8-bit video card (8-bit color) Uses 8 bits to store information about each pixel Can display 256 different colors 2 8 = 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 256 colors

54 What are various video standards? The Video Electronics Standards Association (VESA) develops video standards

55 Computer System Types Network computer Personal computer Workstation Midrange computer Mainframe computer Supercomputer


57 Selecting and Upgrading Computer Systems Computer system architecture: the configuration of a computer systems hardware components

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