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I.Ch 8 Secondary Storage
A.Competencies page 210
1.Distinguish between primary and secondary storage.
2.Describe the traditional floppy disk and compare it to
high capacity floppy disks.
3.Compare internal hard disks, hard-disk cartridges, and
hard-disk packs.
4.Describe ways to improve hard-disk operations,
including disk caching, redundant arrays of inexpensive
disks, and data compression and decompression.
5.Describe the different types of optical disks.
6.Describe solid state storage, Internet drives, and
magnetic tape.
B.Introduction page 211
Secondary storage devices are used to save, to back up, and even to transport files consisting of data or programs from one location or computer to another. The need for storage continues to grow due to higher demands of users to store more digital media such as videos, music, and images. Data is stored on secondary storage in digital or machine code, so it doesn’t need to be translated from the 1s & 0s when it is sent to the CPU for processing.
C.Storage page 212
RAM (Random Access Memory) is called primary storage since it is used directly by the CPU for processing data and program instructions. RAM is volatile or temporary storage (once the power is turned off, the contents are lost). Secondary storage provides permanent or non-volatile storage. Secondary storage devices read and write the data onto the storage medium. Reading is the process of retrieving/accessing the data. Writing is the process of storing/saving the data. Important characteristics of secondary storage include: Media or medium: the physical material that holds the data
Capacity: measures how much the media can store, typically measured in MB, GB, and TB Storage devices: hardware that reads (and often writes) to storage media Access speed (aka access time): measures the amount of time to read and/or write to the storage medium D.Floppy Disks Floppy disks (aka floppies, diskettes, disks or flexible disks) are portable, removable storage media. The use flat circular pieces of Mylar plastic coated with a magnetic material to store data. Floppy Disk Drives (FDD) store/retrieve data by magnetizing spots according to an encoding scheme such as ASCII, EBCDIC, or Unicode.
1.Traditional Floppy Disk page 213
Traditional disk is the 1.44 MB 3 ½” disk, introduced in the 1980’s 2HD disks are “two sided, high density” Density refers to how tightly the bits can be packed on the medium A Shutter slides to provide access to the plastic medium Labels can be applied to the external surface of the disk to identify the contents A Write-Protection Notch can be moved to protect the disk from accidentally writing over it. Floppies store the data in a series of Tracks and Sectors – each sector can store up to 512 bytes or characters.
2.High Capacity Floppy Disks page 214
High Capacity Floppy Disks (aka floppy-disk cartridges) have capacities of much higher than traditional floppies. Three leading types include: Zip Disks (sold by Iomega) have 100, 250, or 750 MB capacities and connect to the PC via USB cable. The disks are slightly thicker than traditional floppies, so they require special disk drives. HiFD disks (from Sony Corporation) have 200 MB or 720 MB capacities. The main advantage is the drives can also read traditional 1.44 MB floppies. SuperDisks (from Imation) have a 120 MB or 240 MB capacity, and the drives can also read traditional 1.44 MB floppies. E.Hard Disks page 215 Hard disks save files by altering magnetic charges of the disk’s surface Hard disks use a thicker, rigid metallic platter for the base medium
data. Popular programs for compressing files include WinZip and PKZip. The smaller size comes at a price, since it takes a little longer to uncompress the data. F.Optical Disks page 219 Optical disks can hold close to 17 GB of data – enough to store over several million typewritten pages or a medium sized library on a single disk. Optical disks use reflected light rather than magnetized spots. Binary 1s and 0s are represented by flat areas called “lands” and bumpy areas called “pits” Unlike hard disks that have concentric tracks, optical disks have a single spiral track that is divided into equally sized sectors for storing data. The most common sized optical disk is 4 ½ inches, and typically stored in a plastic “jewel box”
1.Compact Disc (CD)
One of the most widely used optical formats Typically store 650 MB to 1 GB (1,000 MB) on one side of a CD Rotational speed determines how fast data can be transferred to the CPU 24X (24 speed) CD can transfer data at 3.6 MB per second 48X (48 speed) CD can transfer data at 7.2 MB per second a)Read Only - CD-ROM Compact Disc – Read Only Memory is similar to a commercial music CD RO means it can not be written over by the user Typically used to deliver large databases, references, or software applications b)Write once - CD-R Compact Disc – Recordable: write once, read many CD burners typically use these to archive data or record music c)Rewriteable - CD-RW Compact Disc – ReWritable: write many, read many Used to create and edit multimedia presentations Typically cost a little more than CD-R d)Photo CD (aka Picture CD) A special format developed by Eastman Kodak for storing digital images
Disks are typically single session – all images are written once, but may be read many times Photo CDs are now multisession – images can be added later
2.Digital Versatile/Video Disc (DVD) page 220
A newer format that is replacing CD optical disks DVDs can store 4.7 GB to 17 GB on a single disk a)Read only - DVD-ROM Written at manufacturing plant, read many Typically used for video distribution b)Write once - DVD-R DVD+R Write once, read many Tend to cost more than CD writable disks Used for archiving data and writing video files c)Rewriteable - DVD-RW DVD+RW DVD-RAM Write many, read many Still working on setting a standard format G.Making IT Work for You – Music from Internet page 222 This section briefly describes how you can find music on the Internet, and transfer it to a portable player.
1.Finding Music
Many sites on line – best to look for current sites
2.Creating a Custom CD
Several different programs can burn a CD for you Look at the software that comes with your CD burner, or look for some on line.
3.Uploading to a Portable Player
Transfer the files to the portable player of your choice You may need to find the file formats that work with your player: mp3, wav, au, etc. H.Other Types of Secondary Storage page 221
1.Solid-state storage
These devices have no moving parts, so they are fast and reliable
Storage devices Access time or Access speed
2.Floppy Disks
a)Traditional Floppy Disk b)High Capacity Floppy Disks
(1)Zip disks
(2)HiFD disks
(3)SuperDisk disks
3.Hard Disks
a)Internal hard disk b)Hard-disk Cartridge
4.Hard Disks
a)Hard-disk Pack b)Performance Enhancements
(1)Disk caching
(2)RAID (Redundant Array of Inexpensive Disks)
(3)File Compression/Decompression
5.Optical Disks
a)Compact Discs
(1)CD-ROM
(2)CD-R
(3)CD-RW
(4)Photo CD
b)Digital Versatile Discs
6.Other Types
a)Solid-State b)Internet hard drives c)Magnetic Tape K.Key Terms page 231 1 1.44 MB 3 1/2-inch disk traditional sized floppy disk, the standard for portable storage for 20 years 2 2HD two sided, high density indication found on 3 1/2 inch floppy diskettes 3 access speed aka access time; time it takes to read data from a storage medium and send it to the processor 4 access time aka access speed; time it takes to read data from a storage medium and send it to the processor 5 C drive typical "mapping letter" for a local hard drive on a Windows based PC 6 capacity amount of data that can be stored, typically measured in bytes 7 CD (compact disk) optical disk format for storing multimedia data, typically up to 650 MB 8 CD burner aka CD drive, allows a user to save data on a recordable CD disk 9 CD-R (CD-recordable) special CD format that can be written once, read many times 10 CD-ROM (compact disc- read only memory) CD format that is written by a manufacturer, but readable many times by the buyer - often used for music CDs 11 CD-RW (compact disc rewritable) CD format that can be written and read many times, often used for backup purposes 12 cylinder set of similar tracks on different disk platters in a hard disk storage system 13 density the amount of data that can be stored on a medium 14 direct access ability to find data on storage without having to read through it sequentially 15 disk aka floppy, a small, portable plastic medium for storing data 16 disk caching technique to speed up disk access by storing the most recently used data in electronic memory (chips) 17 diskette aka floppy, a small, portable plastic medium for storing data 18 DVD (digital versatile disc or digital video disc) optical format used for storing large amounts of multimedia data, up to 17 GB 19 DVD player driver for reading DVD disks 20 DVD-R or DVD+R (DVD recordable) re-writable format for DVD, fairly new technology replacing writable CD technology 21 DVD-RAM (DVD-random- access memory) re-writable format for DVD, fairly new technology replacing writable CD technology 22 DVD-ROM (digital versatile disc-read only memory) readable DVD format typically used for movies 23 DVD-RW or DVD+RW (DVD rewritable) re-writable format for DVD, fairly new technology replacing writable CD technology 24 erasable optical disk generic term for re-writeable optical formats including CD-RW 25 file compression technique to eliminate redundant data from files to shrink their size for better storage and transport 26 file decompression opposite of compression, it's restoring of files from a compressed format e.g. unzipping a file 27 fixed disk aka internal hard disk; metallic platters storing GBs worth of data for fast access 28 flash memory card solid state storage device often used in digital cameras to store electronic photos 29 flexible disk aka floppy, a small, portable plastic medium for storing data 30 floppies aka floppy, a small, portable plastic medium for storing data 31 floppy disk aka floppy, a small, portable plastic medium for storing data 32 floppy disk drive FDD the device for reading and writing data on floppy disks 33 floppy-disk cartridge aka high capacity floppy disks; newer diskette technology to store 100 MB or more 34 hard disk aka fixed disk; metallic platters storing GBs worth of data for fast access 35 hard-disk cartridge aka removable hard disks; a portable hard disk 36 hard-disk pack removable storage for massive amounts of data, often used on mainframe systems 37 head crash occurs when the R/W heads touch the surface of the hard disk platters, making it inoperable 38 HiFD disk one type of high capacity floppy disk sold by Sony
L.Chapter Review page 232
1.Crossword
a)Across 3 FIXED Also known as the internal hard drive 8 SECTOR Invisible wedge-shaped division of a track 9 PITSANDLANDS Represent 1s and 0s 10 TRACK Rings of concentric circles without visible grooves 11 RAID Grouped disk drives treated as one hard disk by the computer system 13 ZIP Disk with 500 times the storage as a standard floppy 14 FLOPPY Portable and removable storage device 15 WRITING The process of saving information to the secondary storage device 16 PLATTER Rigid metallic part of a hard disk 17 DISKETTE Storage medium that contains a flexible plastic disk b)Down 1 DISKCACHING Improves hard-disk performance by anticipating data needs 2 MULTISESSION Meaning new images can be added to a CD at any time 4 CYLINDER Runs through each track of a stack of platters 5 ACCESSTIME Measures the amount of time required to retrieve data 6 SECTOR Invisible wedge-shaped section 7 ONLINESTORAGE Web based storage 12 DENSITY How tightly the bits can be packed next to each other
2.Multiple Choice page 233
1 A Nonvolatile storage 2 A Reading 3 D Access time 4 E All of the above 5 * None of these – DENSITY – see page 213 6 B Open 7 C C (drive) 8 B Fixed disk 9 D DVD-ROM 1 0 C Magnetic tape
3.Matching page 234
TERM MATCH NUMBER HINT RAM Q 1 A type of storage that is volatile writing T 2 The process of saving a file to a secondary storage device access speed A 3 Time required to retrieve data and programs floppy disk I 4 Also known as a diskette or disk track S 5 Closed concentric ring on a disk on which data is recorded sector N 6 Wedge-shaped section of a track floppy disk cartridge J 7 Zip disks, SuperDisks, HiFD disks cylinder C 8 Runs through each track of a stack of platters hard disk pack K 9 Several platters aligned one above the other, allowing greater storage capacity disk caching D 10 Hardware and software that anticipates data needs file compression F 11 Increases storage capacity by reducing the amount of space required to store data and programs jewel box M 12 Used to protect optical disks CD burner B 13 CD-R drive Picture CD P 14 Special CD format for storing digital pictures solid-state storage R 15 Stores data electronically and has no moving parts flash memory card H 16 Solid state storage device used in portable computers i-drive O 17 Free or low cost storage available at special service web sites disks E 18 Provide fast direct access tapes L 19 Provide slower sequential access fixed disk G 20 Also known as internal hard drive
4.Open-ended
a)Describe the three most likely successors to the 1. MB 3 1/2 inch floppy. May want to look at the three types of High Capacity Floppy disks: Zip Disks, HiFD disks, and SuperDisks May want to argue for optical disks: CD or DVD since they are becoming cheaper May also argue for portable solid state storage such as “key chain hard drives” b)What are the three types of hard disks? What is so disastrous about a head crash? Three types include internal hard drives, hard-disk cartridges, and hard-disk packs (may also want to mention external hard drives and RAID systems) A head crash occurs when a read/write head touches the disk surface, which can ruin a hard drive. c)Describe three ways to improve hard disk performance. Disk caching: reading a portion of the disk into RAM to improve response time
N.Expanding Your Knowledge page 236
1.How Music is Downloaded from the Internet
Review the animation “How Music is Downloaded” from the text’s CD and/or Web site Discuss different Web based music sites and their advantages and disadvantages Discuss ways to play music from the web (may focus on MP format and the different types of players available)
2.File Compression
Study the expansion “File Compression” on the text’s CD and/or Web site. Discuss different types of compression (lossy, lossless, etc.) and it’s use for different applications (text, images, videos, music, etc.).
O.Building Your Portfolio page 237
1.DVD
Students are asked to write a one page paper titled “DVD Technology” and answer questions discussed in the text, such as a) Define DVD-ROM, DVD-R, etc. May recommend that students research these topics on line – look at some electronic retailer sites to learn about the costs and features of some of these items.
2.CD-R and Music Files
Students are asked to write a one page summary about downloading and copying music files. Reply to questions such as “Is it fair to make a copy of a CD you have purchased on your computer”? – yes, if it’s for backup purposes May want to have your students perform some research about federal government sites addressing “fair use” as well as read through the “fine print” on licensing agreements.
II.Concept Checks at a glance
A.Ch 8 page 214
1.Discuss four important characteristics of secondary
storage.
Media or medium: the physical material that holds the data
Capacity: measures how much the media can store, typically measured in MB, GB, and TB Storage devices: hardware that reads (and often writes) to storage media Access speed (aka access time): measures the amount of time to read and/or write to the storage medium
2.What is the traditional floppy disk? Why is it likely to be
replaced in the future?
Traditional disk is the 1.44 MB 3 ½” disk, introduced in the 1980’s 2HD disks are “two sided, high density” Density refers to how tightly the bits can be packed on the medium A Shutter slides to provide access to the plastic medium Labels can be applied to the external surface of the disk to identify the contents A Write-Protection Notch can be moved to protect the disk from accidentally writing over it. Floppies store the data in a series of Tracks and Sectors – each sector can store up to 512 bytes or characters It is likely to be replaced because newer technologies have exceeded it’s capacity, speed, and portability. B.Ch 8 page 218
1.Compare floppy and hard drives. What is a head crash?
Floppy drives are meant to be portable. They are slower than hard drives, but the capacity is limited only by the number of diskettes that are used. Floppies also plastic for the main storage medium Hard drives are much faster, but generally not as portable as a floppy, since they are often “built into the machine”. Hard drives use a metallic disk for the storage medium. A “head crash” can occur when the read/write head of the drive touches the surface of the disk, therefore destroying the data. These once occurred frequently, but newer technology drives have increase the MTBF – Mean Time Between Failures.
2.What are the three types of hard disks? Briefly describe
each.
a)Internal Hard Disk Also known as a fixed disk Located inside the system unit or chassis Typically mapped as the “C:” drive Advantages are speed and capacity: a 100 GB HD can hold as much as 70,000 traditional 1.44 MB floppies = (100 * 2^30) / 1,440,
2.Compare CD and DVD formats. Why are DVDs replacing
CDs?
CDs typically hold up to 650 MB, while DVD formats can hold close to 17 GB (almost 30 x more than CDs). CD formats are older and more established, but they are slowly being replaced by DVD formats DVDs are replacing CDs because of their higher capacity and the cost of the technology has fallen. As users demand more and more data capacity for applications such as video, they will need higher capacity storage media.
3.What are DVD-RW, DVD+RW and DVD-RAM?
They are different formats for the DVD format – they differ in terms of how they can be written/rewritten. Once the standards shake out in the marketplace, many drives will need to support a number of these standards. D.Ch 8 page 225
1.What is solid-state storage? What are key chain hard
drives?
Solid-state storage is electronic storage with “no moving parts” – the data is stored on silicon chips. Examples include flash memory cards and key chain hard drives Flash memory is solid-state memory often used for storing digital images from digital cameras. Key chain hard drives are small storage devices that connect with a computer through a USB port. They can hold close to 1 GB of data, and offer a portable way to store data.
2.What are Internet hard drives? What are they used for?
Internet hard drives (aka i-drives) are regular hard drives that can be accessed via an Internet connection. They are often used for portable storage – so long as you have an Internet connection, you can access the drive. The drawbacks include the speed (limited by the speed of your connection) and privacy/security (do you feel safe with your data stored on someone else’s computer).
3.Discuss magnetic tape reels and tape cartridges.
Tape storage offers only sequential storage. Tape reels were an older technology dating from the 1950s used to store large amounts of data for mainframe computers
Tape cartridges have replaced many of the reel systems, and are used for backing up servers.
III.List of Figures at a glance
- Ch 8 page 212 figure 8-1 Secondary storage media o Photo of an optical disk being inserted into a computer o Media is the actual physical material that holds the data
- Ch 8 page 213 figure 8-2 How charges on a disk store the number 3 o Drawing of how the decimal number 3 is stored as a series of bits on a floppy disk o This number is shown with the ASCII equivalent for the number 3. The first 4 bits indicate it is a number, the second 4 bits indicate the value 0011 = 08 + 04 + 12 + 1
- Ch 8 page 213 figure 8-3 A 1.44 MB 3 ½ inch floppy disk o Photo of the traditional floppy that was the standard for portable storage for close to 20 years
- Ch 8 page 213 figure 8-4 The parts of a 3 ½ inch floppy disk o Cut away image of a traditional floppy disk showing Metal shutter: opens to permit access to the media, closes to protect it Data access area: small open “window” to allow the drives R/W heads to access the media Hard plastic jacket: outside covering of diskette Label: allows user to write notes about contents of the disk Write protection notch: when open it prevents writing to the diskette Inside of disk: diagram of tracks and sectors used to store data on the disk
- Ch 8 page 214 figure 8-5 Zip disk and drive o Photo of an Iomega zip disk & drive, a higher capacity drive that can store anywhere from 100 – 750 MB on a diskette
- Ch 8 page 214 On the Web Explorations o Encourages students to learn more about leaders in high capacity disk storage systems by visiting the text’s CD and/or Web site.
- Ch 8 page 214 figure 8-6 Typical floppy disk capacities o Table listing some storage capacities of diskette media 2HD – 1.44 MB Zip – 100/250/750 MB HiFD – 200/720 MB SuperDisk – 120/240 MB
- Ch 8 page 214 TIPS box – rules for handling diskettes o Don’t bend o Don’t touch
o Create a file o Select o Compress
- Ch 8 page 219 figure 8-15 Optical disk o Photo showing an optical disk (CD or DVD), a popular storage medium for multimedia data
- Ch 8 page 219 TIPS box o Offers tips on protecting your optical disks, including: Don’t stack (them) Don’t touch Don’t remove Avoid extreme conditions Use storage boxes
- Ch 8 page 221 figure 8-16 Types of optical disks o Table listing the Format, Capacity, Type, and Description of some optical disks CD-ROM – read only CD-R – write once CD-RW - rewriteable Picture CD – single session Photo CD – multi-session DVD-ROM – read only DVD-R and DVD+R – write once DVD-RW, DVD+RW, DVD-RAM - rewriteable
- Ch 8 page 224 figure 8-17 Flash memory card o Photo of a Microtech Smart Media card (holds 128 MB) typically used for holding digital photos in a camera
- Ch 8 page 224 figure 8-18 Key chain flash memory o Photo of a small keychain device in a person’s hand. These devices can store around 1 GB of data in a small, portable package
- Ch 8 page 224 figure 8-19 An Internet hard drive site o Screen shot of http://www.xdrive.com site that offered storage via the Internet (in Dec 2004, 5GB for $10 per month)
- Ch 8 page 225 figure 8-20 Internet hard drive sites o Table listing a few Internet hard drive sites including: http://Itools.mac.com http://www.freedrive.com – same as Xdrive http://Briefcase.yahoo.com http://www.Amerivault.com (defunct?) http://www.Connected.com o NOTE: you will probably want to test these sites out, since many of these services are no longer offered
- Ch 8 page 225 figure 8-21 Magnetic tape cartridge
o Photo of a Sony DLT tape, with capacities of 20-80 GB per tape o These are typically used for backup purposes
