Holds data, instructions, and information for future use Storage medium is physical material used for storage

Transcription

1 Chapter 3 Storage

2 Storage What is storage? Holds data, instructions, and information for future use Storage medium is physical material used for storage Also called secondary storage such as : floppy disks, CDs, Zip disks

3 Storage How does volatility compare? Storage medium is nonvolatile contents retained when power is off Memory is volatile holds data and instructions temporarily ON OFF Volat tile No onvolatile Screen Display Memory (most RAM) (chips on motherboard) Storage Medium (floppy disks, Zip disks, hard disks, CDs) Display appears Data and instructions available to user Contents available to user Display disappears Data and instructions erased Contents retained ed

4 Switches Representing Data The on/off state of a switch represents one bit of data. Bit (binary digit) On = 1 Off = 0 OFF ON 01 OR = 1 bit 1 0 Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall

5 Bits and Bytes: The Language of Computers Bit Binary digit 0 or 1 Byte 8 bits Each letter, number, and character = a string of eight ht0s and 1s Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall 5

6 Representing Letters and Symbols American Standard d Code for Information Interchange (ASCII) 8bits= 1byte= alphanumeric character or symbol 256 different combinations Unicode 16 bits equal 1 byte 96,000 different combinations; used for all languages Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall

7 ASCII Chart (American Standard Code for Information Interchange) Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall

8 How Much Is a Byte? Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall 8

9 Storage What is a storage device? Hardware that records and retrieves items to and from a storage medium. Examples are Floppy drive, Hard disk drive etc. Reading Process of transferring items from storage media to memory Hardware that records and retrieves items to and from storage media Writing Process of transferring items from memory to storage media Functions as source Creates output of input

10 Storage What is capacity? Number of bytes (characters) a storage medium can hold Kilobyte (KB) Megabyte (MB) Gigabyte (GB) Terabyte (TB) 1 thousand 1 million 1 billion 1 trillion Petabyte (PB) 1 quadrillion Exabyte (EB) 1 quintillion

11 Floppy Disks What is a floppy disk? Portable, inexpensive storage medium (also called diskette) shutter shell liner Thin, circular, flexible film enclosed in 3.5 wide plastic shell magnetic coating metal hub flexible thin film

12 Floppy Disks What is a floppy disk drive? Device that reads from and writes to floppy disk One floppy drive, named drive A If two floppy drives, second designated as drive B Floppy disk drive built into a desktop computer External floppy disk drive attaches to a computer with a cable

13 Floppy Disks What are tracks and sectors? Track is narrow recording band that forms full circle on disk Sector stores up to 512 bytes of data Formatting prepares p disk for use and marks bad sectors as unusable

14 Floppy Disks What are tracks and sectors? Tracks are configured in concentric circles in which data are stored. PC disks usesector organization i to store and retrieve data. The recording surface is divided into sectors (a disk-storage concept of a pie-shaped p portion of a disk or diskette in which records are stored and subsequently retrieved).

15 Floppy Disks How do you care for a floppy? Proper care helps maximize disk s life Floppy disk can last at least seven years Never open the shutter and touch the disk s surface Avoid exposure to heat and cold Avoid exposure to magnetic Avoid exposure fields to contaminants such as dust, Keep disks in smoke, or a storage tray salt air when not using them

16 Zip Disks What is a Zip disk? Magnetic medium that stores 100 MB or 250 MB of data Used to back up and to transfer files Backup is duplicate of file, program, or disk in case original is lost c Zip disks require a Zip drive chigh capacity drive that reads from and writes on a Zip disk Zip disk External Zip drive

17 Hard Disks What is a hard disk? High-capacity storage Consists of several inflexible, circular platters that store items electronically Components enclosed in airtight, sealed case for protection hard disk installed in system unit

18 Hard Disks What are external hard disks and removable hard disks? Used to back up or transfer files External hard disk freestanding hard disk that connects to system unit Removable hard disk hard disk that you insert and remove from hard disk drive

19 CDs and DVDs What are CDs and DVDs? Flat, round, portable metal discs with protective plastic coating Can be read only or read/write Push the button to slide out the tray. Insert the disc, label side up. Most PCs include CD or DVD drive, most play audio CDs Push the same button Push the same button to close the tray.

20 CDs and DVDs What is a CD-ROM? Compact disc read- only memory Cannot erase or modify contents Typically holds 650 MB to 1 GB Commonly used to distribute multimedia and complex software

21 CDs and DVDs What are CDs and DVDs? CD-ROM stands for compact disc-read-only memory. Once inserted in the CD-ROM drive, the text, video images, and so on can beread it into RAM for processing or display. The data on the disk are fixed-they cannot be altered. This is in contrast to the read/write capabilities of magnetic disks. What makes CD-ROM so inviting is its vast capacity to store data and programs. The capacity of a single CD-ROM is up to 680 MB-about that of 477 diskettes.

22 CDs and DVDs What are CD-Rs and CD-RWs? Must have CD recorder or CD-R Rdrive CD-R (compact disc-readable) disc cdisc you can write on once CD-RW (compact disc-rewritable) ceerasable disc you can write on multiple times Cannot erase disc s contents Must have CD-RW software and CD-RW drive

23 CDs and DVDs What is a DVD-ROM (digital versatile disc-rom or digital video disc-rom)? High capacity disc capable of storing 4.7 GB to 17 GB Must have DVD-ROM drive or DVD player to read DVD-ROM Stores databases, music, complex software, and movies DVD DVD drive

24 CDs and DVDs What are CDs and DVDs? DVDs are poised to replace CD-ROMs. The DVD (digitali videodisk) looks like the CD and the CD-ROM, but it can store from 7 to 14 times as mush information (up (p to about 10 GB). A DVD can store the video for a full-length movie. DVD drives are back-wards compatible; that is, they can play all of your CD-ROM and CDs. DVDs probably will replace videotapes and CDs in a few years

25 CDs and DVDs How is data stored on a CD or DVD? Typically stored in single track Track divided into evenly sized sectors that store items single track spirals to edge of disc disc sectors

26 Tape What is tape? Magnetically coated plastic ribbon capable of storing large amounts of data at low cost Primarily used for backup

27 Tape How is data stored on a tape? Sequential access Reads and writes data consecutively, like music tape Unlike direct access used on floppy disks, Zip disks, hard disks, CDs, and DVDs which can locate particular item immediately

28 Miniature Mobile Storage Media What is miniature mobile storage media? Storage for small mobile devices Miniature mobile storage media

29 Miniature Mobile Storage Media What are common types of miniature mobile storage media? CompactFlash Smart Media Secure Digital Memory Stick Microdrive USBDrive

30 Setting It All Up: Ergonomics Ergonomics: minimizing injury or discomfort while using the computer Steps to follow: Position monitor correctly. Use adjustable chair. Assume proper position while typing. Take breaks. Ensure adequate lighting. Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall 30

31 Ergonomics and Mobile Devices Mobile devices present ergonomic challenges Ergonomic Disease Blackberry thumb ipod deafness Cellular blindness Laptop thighs Laptop shoulder Cause Thumb typing without breaks or stretching can cause DeQuervains tendinitis in the thumbs. Listening through ear buds for prolonged periods at a volume of 80 decibels or more can cause deafness. Extended viewing on tiny screens can cause eye strain and/or dry eyes. Resting a laptop directly on your lap for extended periods of time can result in 1 st and 2 nd degree burns. Large, heavy, one-strap laptop bags can result in neck, shoulder, and back pain and/or strain. Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall 31