Data Storage
File system : A system that an operating system uses
to organize and keep track of its files.
FAT: (File Allocation Table)
- Used by the operating system to locate files on a disk.
- Files may be divided into many sections that are scattered around
the disk. The FAT keeps track of all the pieces.
- FAT formatted partitions cannot be larger than 32gb
NTFS: (NT File System)
- This file system is a journaling file system, which means it is
less likely to become corrupt and will recognize bad sectors and correct
itself.
- To control access to files, you can set permissions for directories
and/or files. NTFS can only be used by Windows NT, 2000, and XP.
- The NTFS contains an MFT (Master File Table) that keeps track of
files on disks.
Types of Memory
- RAM(random-access memory): Data
is able to be written and read to and from this RAM. Most RAM is volatile, which
means that it requires a steady flow of electricity to maintain its
contents. As soon as the power is turned off, whatever data was in
RAM is lost.
-
ROM (read-only memory): This holds instructions
for starting up the computers. Rom cannot be written to. ROMs are non-volatile.
- PROM
(programmable read-only memory): A PROM is
a memory chip on which you can store a program.
After the PROM has been used, you cannot wipe it clean and use it
to store something else. PROMs are non-volatile.
- EPROM (erasable
programmable read-only memory): An
EPROM is a special type of PROM that can be erased by exposing it
to ultraviolet light.
- EEPROM(electrically
erasable programmable read-only memory): An EEPROM is
a special type of PROM that can be erased by exposing it to an
electrical charge.
Storage Sizes
Bit : The smallest unit of information on a machine.
A single bit can hold only one of two values: 0 or 1. Eight consecutive
bits are equal to one byte.
Byte : A unit of storage capable of holding a single
character.
Kilobyte – 1,024 bytes
Megabyte - 1,048,576 bytes
Gigabyte – 1,073,741,824 bytes
Terabyte – 1,099,511,627,776
bytes
Storage Devices
Floppy Disks: A soft magnetic disk to store data
- Relatively slow
- Small capacity
- Portable
- Inexpensive
- Universal
Hard Drive : A hard magnetic disk
to store data
- Very fast
- More capacity than floppy disks
- Expensive
- Not portable
Tapes: A magnetically coated strip of plastic on which
data can be encoded
- Relatively inexpensive
- Portable
- Large storage capacities
- Do not permit random access of data
CD-ROM: A Storage medium which can be read and which
is written by lasers
CD-R – CD-Writable
- Can only be written to once
- Inexpensive
- Cannot be erased
- Portable
- Multi-session recording allows the user to add layers of data at
a later date
- Requires a CD burner
CD-RW – CD-Rewritable
- Can be written to multiple times
- Slightly more expensive than a CD-R
- Can be erased
- Portable
- Requires a CD burner
DVD-ROM: A new type of storage medium that is written
by lasers and can be read
DVD-R
- Write-once disks
- Excellent compatibility with both standalone DVD players and DVD-ROM
drives
- Requires a DVD-R burner to write to disk
DVD-RW
- Rewriteable discs
- Majority of standalone DVD players will play video recorded on DVD-RW
discs
- Requires a DVD-R burner to write to disk
DVD+R
- Not supported by the DVD Forum
- Write-once disks
- Excellent compatibility with both standalone DVD players and DVD-ROM
drives
- Requires a DVD+/-R burner to write to disk
DVD+RW
- Not supported by the DVD Forum
- Rewriteable discs
- Majority of standalone DVD players will play video recorded on DVD+RW
discs
- Requires a DVD+/-R burner to write to disk
DVD+/-R Single sided dual layered
- Holds up to 9.4gb of storage
- Majority of standalone DVD players will play video recorded on DVD-RW
discs
- Requires a dual layered DVD+/-R burner
USB Drive : A small portable hard
drive that plugs into the USB port on a computer
- Easy-to-use
- Small enough to be carried in a pocket
- Plug into any computer with a USB drive
- Durable because they do not contain any internal moving parts
- Less storage capacity than an external hard drive
Flash Memory Cards: A type of EEPROM that can be
erased and written in blocks
- Small
- High data storage capacity
- Not interchangeable with other flash memory
- Used in such items as Cellular Phones, Personal digital assistants,
Digital cameras and Digital printers
References
www.webopedia.com
What is a memory Card?
http://www.bhphotovideo.com/bnh/controller/
home?O=getpage.jsp&A=getpage&Q=Product_Resources/memcard.jsp
Produced by:
The National Child Exploitation
Coordination Centre
Strategic
and Operations Support Services
Research and Development Division
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