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Pertemuan 10Hardware: Secondary Storage Matakuliah : T0604-Pengantar Teknologi Informasi Tahun : 2008 Versi : 2.0/0.0 Sumber: Chapter 4. Hardware: The CPU & Storage, p.189 Williams, B.K, Stacy C. Sawyer (2007). Using Information Technology: A Practical Introduction to Computers & Communications. Seventh Edition, McGraw-Hill, New York. ISBN-13: 978-0-07-110768-6
Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu: • menjelaskan berbagai jenis secondary storage yg ada pada masa kini, dan perkembangannya ke depan (C2)
Outline Materi • Secondary Storage • Future Developments in Processing & Storage
Storage Types Floppy and Zip disks Hard disks Optical disks Magnetic tape Smart Cards Flash memory Online secondary storage Descriptions Removable disks. Floppies store 1.44 MB Zip disks store 100, 250, or 750 MB Made from thin rigid metal covered with magnetizable substrate. Most disks have 2 or more platters Removable CDs and DVDs Thin plastic tape coated with magnetizable substance Like a credit card, but contains a microprocessor and memory chips Nonvolatile memory – no moving parts Lets you store data on an online vendor’s server Secondary Storage
Floppies Flat piece of mylar plastic inside a 3.5” plastic case Store about 1.44 MB Have a write-protect notch Data is recorded in tracks: concentric recording bands Formatting breaks the tracks into small wedge-shaped sectors Read/Write head transfers data between the computer and disk Floppies DO wear out! Zip Disks Disks with a high-quality magnetic coating Store 100, 250, or 750 MB Require a Zip drive; won’t work on floppy drives Used to store larger files than floppies can hold Zip disks wear out too! Secondary StorageFloppies and Zip Disks
Secondary StorageHard Disks • Thin, rigid metal, glass, or ceramic platters covered with a substance that allows data to be held in the form of magnetized spots • The more platters there are, the higher the drive capacity • Store data in tracks, sectors, and clusters • Formatting creates a file allocation table that maps files to clusters or inodes • Typical file systems are VFAT & NTFS for Windows, HFS and ext2 for Unix • Drive heads ride on .000001” cushion of air, and can crash! • Important data should always be backed up!
Secondary StorageHard Disks • Hard Disk Types: • External Hard Disks – a freestanding disk drive • Removable Hard Disk – inserted into a cartridge drive on the PC • Hard Disk Controllers • EIDE – Enhanced Integrated Drive Electronics • Supports up to 4 disks at 137 GB per disk • Marketed as SATA, Fast ATA, Ultra ATA, ATA-2, ATA/100 • SCSI – Faster than EIDE controllers • Fibre Channel – used in large servers – faster and costlier than SCSI
Secondary StorageOptical Disks • CDs and DVDs are Optical disks • Data is written and read using lasers, not a disk head • CD-ROM is Compact Disk Read-Only Memory • CD-R is used for recording only once • CD-RW is an erasable optical disk that can both record and erase data over and over again • DVD is a CD-style disk with extremely high capacity • Stores 4.7 or more GB • DVD-R is used for recording only once • DVD-RW, DVD-RAM, DVD+RW are reusable DVDs
Secondary StorageMagnetic Tape • Thin plastic tape coated with a substance that can be magnetized • Store 200 GB and higher • Used in the form of tape cartridges • Still popular for large backups because of their large data capacity • But don’t get it near a magnet as that will erase it!
Secondary StorageSmart Cards • Resembles a credit card, but contains a microprocessor and memory chips • Holds more information than standard magnetic-strip credit cards; 8 – 40 MB of data • UltraCard • Uses a magnetic shim that draws out of the card to be read, then retracts into the drive • Provides 2 GB of storage • Contact smart cards • Must be swiped through card readers • Can wear out from use • Contactless smart cards • Read when held in front of a low-powered laser
Secondary StorageFlash Memory • Nonvolatile memory with no moving parts • But the electronics can wear out • Available as • Flash memory cards • Insert these into a flash port of a camera, handheld PC, smartphone • Flash memory sticks • A form of flash memory that plugs into a memory stick port • Flash memory drives • A finger-sized module of flash memory • Plugs into the USB port of most PCs and Macintoshes
Secondary StorageOnline Secondary Storage • Allows you to use the internet to back up your data • Sign up with a vendor and receive access to software that allows you to upload your data to that company’s server • Files should be encrypted to maintain security • Use only for vital files that require immediate availability • Use tape, removable hard disk cartridges, zip disks, optical storage or tape for normal backup
Future Developments in Processing & Storage • Moore’s Law • Gordon Moore predicted the number of transistors on a silicon chip will double every 18 months • It has held up since the 1960s!
New Technology M-RAM OUM Nanotechnology Optical Computing DNA Computing Quantum Computing Description of Processing Technology Magnetic RAM uses miniscule magnets rather than electrical charges Ovonic Multiplied Memory stores bits by generating different levels of low and high resistance on a glossy material Tiny machines work at a molecular level to make nanocircuits Uses lasers and light, not electricity Uses strands of synthetic DNA to store data Based on quantum mechanics and stores information using particle states Future Developments in Processing & Storage
New Technology Higher-density disks Molecular electronics Description of Storage Technology Magnetic disk drives currently hold 100 GB of data Blank CDs are replacing floppy disks since they hold 650MB and cost < $1 each DVD disks hold up to 4.7 GB of data currently Perpendicular recording technology allows 25% - 100% more data to be stored on the same disk Polymer memory creates chips that store data on plastics Nonvolatile memory Data is stored based on polymer’s electrical resistance Future Developments in Processing & Storage