Advanced Information Storage 07

Transcription

1 Advanced Information Storage 07 Atsufumi Hirohata Department of Electronics 16:00 24/October/2013 Thursday (V 120) Quick Review over the Last Lecture LTO Storage : mm wide tape / Track width : Length : tracks µm m < µm left / right distributions < nm surface roughness Top ferromagnetic layer Bottom non-magnetic layer Smooth base film (PET, PEN or PA) 70 ~ 80 % thickness Back coating Servo-signal Servo-band Track width : 8.1 µm *

2 07 Development of Magnetic Storages Drum memory Core memory Bubble memory Floppy disk Storage hierarchy Punched Tape Punched tapes were originally used for teletypes : * 0.1-mm thick tapes were used. American Standard Code for Information Interexchnage (ASCII) standardised the format in inch wide tape inch diameter holes with 0.1-inch separation 7-level code including feed holes Long lifetime Easy to repair No magnetic damages Easy to dispose Low fidelity Easy to damage Low recording density Limited usage *

3 Punched Card Punched cards were originally used for loom patterns : * In 1832, Semen Korsakov used for informatics. Charles Babbage proposed a calculating machine, Number Cards. Herman Hollerith invented a tabulating machine in Tabulating Machine Company (1896) IBM 80-column card in dollar note size 80-characters column programming Long lifetime Easy to sort No magnetic damages Easy to dispose Difficult to miniaturise Remaining punched out bits Low recording density * Magnetic Drum Memory In 1932, Gustav Tauschek invented a magnetic drum memory : * Widely used in 1950s and 60s. Ferromagnetic materials are coated on a drum. ** Read / write heads are placed in one line with defining tracks. Slow access Mechanical failure Small capacity * *; ***

4 Magnetic Core Memory In 1949, An Wang and Way-Dong Woo invented Pulse Transfer Controlling Device : * Random access memory for a computer Widely used between 1955 and 75. Magnetic toroids, cores, store data Current applications to two wires write data. Data is read by measuring a sensing wire current. Fast access speed Non-volatility Cheap Reliable (> vacuum tube) Read-out erases data. Accidental data loss Magnetic Bubble Memory In 1967, Andrew H. Bobeck invented a magnetic bubble memory : * Widely used between 1970s and 80s 4,096 bits / cm 2 Conventional stripe magnetic domains can be converted into cylindrical domains. The size of such cylindrical domains can be controlled by an external magnetic field. These domains disappear under a critical magnetic field. Magnetic bubble Large capacity Non-volatility Cheap Robust against vibration and dust Accidental data loss * *

5 Memory architecture : * Magnetic Bubble Memory Operation * * Floppy Disk In 1969, IBM introduced a flexible diskette : * Widely used until 1990s. 8-inch disk : kb ~ 1.2 MB 5 ¼-inch disk : 110 kb ~ 1.2 MB 3 ½-inch disk : 264 kb ~ 200 MB Removable Basic Input / Output System (BIOS) compatible Non-volatility Cheap Fragile against vibration and dust Magnetic field and ultra-violet (UV) light High temperature and humidity

6 Specifications : * Floppy Disk Sizes Disk diameter 8-inch 5.25-inch 3.5-inch Introduction 1970 ~ 1976 ~ 1980 ~ Developer Main demand IBM Programme loading Shugart Technology (Seagate Technology) Miniaturisation Sony High fidelity Coercivity 300 Oe 300 Oe 720 Oe Recording density kb ( kb) MB MB Track density TPI TPI TPI Magnetic core Laminated Straddle Bulk * Floppy Disk Media Media parts : * HD indicating hole Hub for rotation Shutter Plastic housing Polyester sheet to reduce friction against the housing Magnetically coated plastic disk Schematic data sector

7 Floppy Disk Head A head core requires the following features : * Large saturation flux density Large magnetic permeability Small coercivity Wear-proof Magnetic permeability ferrites ferrites ferrites Frequency (khz) head Read / Write (R / W) head Track width (TW) for ERASE Track width (TW) for R / W data Track width (TW) for R / W data TW for ERASE * Partial Response, Maximum Likelihood A method to convert ambiguous signals to digital signals : * *

8 Floppy Disk Drive Drive parts : * * Floppy Disk and CD-ROM Track configurations of a floppy disk and a CD-ROM disk : * Floppy disk CD-ROM disk (FD, HDD and MO) Small capacity Fast access speed (CD, MD, DVD and BD) Large capacity Slow access speed *

9 Constant Angular / Linear Velocity Constant angular velocity : * Constant linear velocity : * Data tracks Data tracks Detecting laser / read head Detecting laser / read head Constant velocity Variable velocity SuperDisk In 1996, Matsushita (Panasonic) and Imation developed a SuperDisk : * Precise tracking by laser-positioning to grooves between the tracks. 3.5-inch disk : 120 ~ 240 MB FD32MB : 1.4 MB 2HD floppy 32 MB tracks : sectors :56 ~ 36 Backward compatibility BIOS (partially) compatible 2 faster access speed than a FD Expensive

10 Zip Drive In 1994, Iomega developed a Zip drive : * 3.7-inch disk media First product : 100 MB Later 250 and 750 MB Magnetic thin layer : Advanced super Thin layer & high Output Metal Media (ATOMM) developed by Fujifilm. Very fast access speed (1.0 Mbps) Cheap drive High data density Direct connectability with a Parallel / SCSI port Expensive media as compared with a MO Upward compatibility A 750-MB drive cannot write a 100-MB disk. Click of death Permanent damage to the head by hitting to the protector of head movement. Jaz Drive In 1995, Iomega developed a Jaz drive : * 3.5-inch disk : 1 GB Upward compatibility : 2 GB Fast access speed similar to a HDD (5.4 Mbps) Overheat Media stuck in a drive Metal slides introduces plastic debris. Noisy rotation Failure of anti-gyro system

11 REV Drive In 2003, Iomega introduced a REV drive to replace a Jaz drive : * 2.5-inch disk : 35 GB Upward compatibility : 70 and 120 GB Fast access speed : 25 Mbps Dust-proof Anti-vibration 30-year life (> 1M times rewritability) Expensive Hierarchy of Information Storage For a Neumann machine, a central processing unit (CPU) controls the storages : * / / non-volatile For volatile memories, static / dynamic Read/write, read only or write once Random / sequential access Location, file or content addressable Destructive / non-destructive read