Outline. Storage Devices. Comparisons. Why is storage necessary? Read/Write and Read-Only media. Types of Storage

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1 Outline Storage Devices Storage devices Storage hierarchy Disk drives Hard disks Magnetic tape CD-ROM Drives DVD-ROM Drives Other storage devices Storage devices 1 Storage devices 2 Why is storage necessary? Comparisons Two types of storage Volatile: RAM -- for working storage Nonvolatile: secondary storages -- for long-term storage Much cheaper than memory Does not transfer data as fast as memory Store setup information for BIOS at the startup Store application software Store result data MEMORY STORAGE Device Cache Memory RAM Hard Disk CD-ROM disc Backup tape Access Speed Fastest Fast Medium Slow Very slow Cost/MB Highest High Medium Low Lowest Storage devices 3 Storage devices 4 Types of Storage Types of storage determined by Operations -- read or read/write Method used to access information -- sequential or random access Technology magnetic, optical or combination of the two Location in the storage hierarchy Read/Write and Read-Only media Read/write media enables a computer to perform reading and writing operations such as diskettes A computer can only perform reading from Read-only media such as CD-R discs Storage devices 5 Storage devices 6 1

2 Sequential and Random-Access Storage Sequential storage device:information can be accessed through the order that information is arranged Random-access storage device: information can be accessed directly without going through the order that information is arranged Storage Technology Magnetic storage media: the media is coated by magnetic substance such as tapes or disks an electromagnetic read/write head records information by transforming electrical impulses into a varying magnetic field that forces the particles to be arranged as a pattern. Optical storage media: Use laser beams to to read microscopic patterns of data encoded on the surface of plastic discs Storage devices 7 Storage devices 8 Storage Hierarchy Access time On-line storage (primary storage): a storage that is actively accessible by the computer without human interaction hard disk Near-on-line storage (secondary storage): A storage that can be accessible by the computer with human interaction diskettes, CD-ROM disc Offline storage (archival storage): use as a backup Magnetic tape Device Static RAM (SRAM) Dynamic RAM (DRAM) Solid state disk (SSD) Hard disk drive CD-ROM drive Typical Access time 5-15 nanoseconds nanoseconds 0.1 millisecond 6-12 milliseconds milliseconds Storage devices 9 Storage devices 10 Data Storage Devices Floppy drive/floppy disk (diskette) A floppy disk is a circular plastic coated with magnetic film same material as on a cassette tape MB Use head actuator to move read/write head over the disk surface Hard Drive/Hard Disk A hard disk is a high capacity, high-speed storage. Interfaces: provides communication from processor to hard disk IDE (Integrated Device Electronics) / EIDE (Enhanced Integrated Device Electronics) Ultra ATA -- Advanced Technology Attachment SCSI (Small Computer System Interface) Storage devices 11 Storage devices 12 2

3 Hard Drive Storage devices 13 Storage devices 14 Removable Drives Zip drive , 250, 750 MB Jaz drive -- 2 GB Thumb drive -- 64, 128, 256 MB Magnetic tapes CD-ROM Disc/Drive CD-ROM (Compact Disc Read Only Memory) drives are CD-Players inside of a computer that can range of speeds from 1x and beyond and has the capability of playing audio CDs and also computer data CDs CD-R, CD-WO (Write once) or WORM (Write Once Read Many) drive or disc. CD-R discs are discs are capable of having information written to the disc once and then read many times after that. Store up to 650 Mb Storage devices 15 Storage devices 16 DVD-ROM Disc/Drive DVD (Digital Versatile Disc or Digital Video Disc) is a new type of CD-ROM drive that allows for large amounts of data on one disc the size of a standard Compact Disc, being used for DVD movies however are also being used for games and storage mediums. Store up to 17 Gb Flash Memory Cards Uses solid state storage system Smart media card Compact flash card Memory stick Storage devices 17 Storage devices 18 3

4 Pen Drives Review Questions Storage devices 19 Storage devices 20 Problem 1 Problem 2 Which of the following storage devices do not use magnetic-sensitive materials for recording information? a) CD-ROM drive b) tape drive c) hard disk drive d) floppy disk drive Storage hierarchy consists of which of the following three levels? a) offline storage, random-access storage, online storage b) online storage, near-online storage, offline storage c) online storage, offline storage, read/write storage d) online storage, near-online storage, optical storage Storage devices 21 Storage devices 22 Problem 3 Problem 4 Which of the following is not a random accessible storage medium? a) tape b) CD-ROM c) hard disk d) floppy disk Which of the following enables you to turn any floppy disk into a read-only disk? a) head actuator b) write-protect tab c) sector d) read/write head Storage devices 23 Storage devices 24 4

5 Problem 5 The technology that follows CDs to be rewritten is known as? a) CD-RAM b) CD-ROM c) CD-RW d) CD-R Problem 6 Removable hard disks are what kind of storage medium? a) online storage b) near-online storage c) offline storage d) sequential storage Storage devices 25 Storage devices 26 Problem 7 FAT means? a) Floppy Advanced Transfer b) Fixed All-purpose tape c) Fast access time d) File allocation table Storage devices 27 5