Lecture 9 Storage. www.shahidrasul.com. Storage. What is storage ?. Holds data, instructions, and information for future use. Storage medium is physical material used for storage. Also called secondary storage. Storage. Kilobyte (KB). 1 thousand. Megabyte (MB). 1 million. Gigabyte (GB).
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Functions as source of input
Hardware that records and retrieves items to and from storage media
Process of transferring items from storage media to memory
Process of transferring items from memory to storage media
Memory (most RAM)
Items waiting to be interpretedand executed by the processor
Operating system, applicationsoftware, user data and information
Flash Memory Cards and USB Flash Drives
Digital pictures or files to be transported
CDs and DVDs
Software, backups, movies, music
Small files to be transported
Trackis narrow recording bandthat forms fullcircle on disk
Sectorstores up to512 bytesof data
Formatting prepares disk for use and marks bad sectors as unusable
Thin, circular, flexible film enclosedin 3.5” wide plastic shell
flexible thin film
Sectors per track:18
Bytes per sector:512
Sectors per disk:2880
Characteristics of a3.5-inch High-DensityFloppy Disk
hard disk installedin system unit
Sample Hard Disk Characteristics
Advertised capacity120 GB
Bytes per second512
Sectors per track63
Sectors per drive234,441,648
Revolutions per minute7,200
Transfer rate133 MB per second
Access time8.9 ms
Step 3.When software requests a disk access, read/write heads determine current or new location of data.
Step 2.Small motor spins platters while computer is running.
Step 4.Head actuator positions read/write head arms over correct location on platters to read or write data.
Step 1.Circuit board controls movement of head actuator and a small motor.
first requestfor data—to disk cache
second requestfor data—to hard disk
Removable hard disk—hard diskthat you insert and removefrom hard disk drive
External hard disk—freestandinghard disk that connects to system unit
SATA (Serial Advanced Technology Attachment) controller uses serial signals to transfer data, instructions, and information
EIDE (EnhancedIntegratedDrive Electronics) controller supports four hard disks, provides connections for CD and DVD drives
Chip and circuits that control transfer of items from disk
SCSI(SmallComputerSystemInterface)controller supports up to fifteendevices including hard disks, CDand DVD drives, tape drives, printers,scanners, network cards
Push the button toslide out the tray.
Insert the disc,label side up.
Push the same buttonto close the tray.
p. 366 Fig. 7-19
Step 3.Reflected light is deflected to alight-sensing diode, which sends digital signals of 1 to computer. Absence of reflected light is read as digital signal of 0.
Step 2.If light strikesa pit, it scatters. If light strikes a land, it is reflected back toward diode.
Step 1.Laser diode shines a light beam towarddisc.
single trackspirals to edgeof disc
Do not exposethe disc to excessiveheat or sunlight
Do store thedisc in a jewelbox whennot in use
Do noteat, smoke, ordrink neara disc
Do not stack discs
Do hold a discby its edges
Do not touchthe undersideof the disc
Ranges from 48X to 75X or faster
75 150 KBps = 11,250 KBps or 12.25 MBps
75X is 150 KBps (KB per second)
48X: 48 150 KBps = 7,200 KBps or 7.2 MBps
Stores digital versions of roll of film
Film developers offer Picture CD service
Can be modified using photo editing software
Step 1.Drop off film to be developed. Mark the Picture CD box on the film-processing envelope.
Step 3.At home, print images from Picture CD on your ink-jet photo printer.
Step 2.When you pick up prints and negatives, a Picture CD contains digital images of each photograph.
At a store, print images to Picture CD at kiosk.
Must haveCD recorderor CD-R drive
CD-R (compact disc-recordable)
—cdisc you can write on once
Cannot erasedisc’s contents
CD-RW (compact disc-rewritable)
—ceerasable disc you can write onmultiple times
Must haveCD-RW softwareandCD-RW drive
xD Picture Card
Microfilm — 100- to215-foot roll of film
Microfiche — small sheet of film, usually 4” 6”
Store microscopic images of documents on roll or sheet of film
Images recorded using computer output microfilm recorder
Small Office/Home Office (SOHO)
Internal hard disks
Portable hard disks
Flash memory cards and USB flash drives
Smart cards, microfilm, and microfiche