1. Information Storage and Spintronics 05
Atsufumi Hirohata
Department of Electronic Engineering
15:00 Monday, 15/October/2018 (J/P 004)

2. Quick Review over the Last Lecture
LTO Storage :
12.65 mm wide tape / 1280 tracks
Track width : 8.1 mm
Length : 800 m
< 5 mm left / right distributions
< 10 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
320
320
1280
320
320
Track width :
8.1 mm *

3. 05 Development of Magnetic Storages
Drum memory
Core memory
Bubble memory
Floppy disk
Storage hierarchy

4. 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
1-inch wide tape
0.072-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 *

5. 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 *

6. 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
® Magnetic core memory
Small capacity
® Hard disk drive *
*** **

7. 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)
® Used in a space shuttle.
Read-out erases data.
Accidental data loss *

8. 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 * **

9. Magnetic Bubble Memory Operation
Memory architecture : * * **

10. 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 *

11. Shugart Technology (Seagate Technology)
Floppy Disk Sizes
Specifications : *
Disk diameter
8-inch
5.25-inch
3.5-inch
Introduction
1970 ~
1976 ~
1980 ~
Developer
IBM
Shugart Technology (Seagate Technology)
Sony
Main demand
Programme loading
Miniaturisation
High fidelity
Coercivity
300 Oe
720 Oe
Recording density
400 kB (800 kB)
1 MB
2 MB
Track density
48 TPI
96 TPI
135 TPI
Magnetic core
Laminated
Straddle
Bulk *

12. 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 *

13. Magnetic permeability
Floppy Disk Head
A head core requires the following features : *
Large saturation flux density
Large magnetic permeability
Small coercivity
Wear-proof
ferrites
ferrites
Magnetic permeability
ferrites
Frequency (kHz)
Read / Write (R / W) head
head
Track width (TW) for ERASE
Track width (TW) for R / W data
Track width (TW) for R / W data
TW for ERASE *

14. Partial Response, Maximum Likelihood
A method to convert ambiguous signals to digital signals : * *

15. Floppy Disk Drive Drive parts : **

16. Floppy Disk and CD-ROM
Track configurations of a floppy disk and a CD-ROM disk : *
Floppy disk
CD-ROM disk
Concentric
Spiral
Track starts from periphery
Track starts from internal circumference
Constant angular velocity
(FD, HDD and MO)
Constant linear velocity
(CD, MD, DVD and BD)
Small capacity
Fast access speed
Large capacity
Slow access speed *

17. 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 *

18. 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 : 80 → sectors :56 ~ 36
Backward compatibility
BIOS (partially) compatible
×2 faster access speed than a FD
Expensive *

19. 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. *

20. 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 *

21. 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 *

22. Hierarchy of Information Storage
For a Neumann machine, a central processing unit (CPU) controls the storages : *
On-line / off-line
Volatile / 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 *