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Storage
holds data, instructions and information for future use
Storage Device
Storage device refers to the apparatus for recording computer data. Examples are the RAM, floppy drives, ZIP drives, and other disks drives
Storage media
storage media are the materials on which data are written and stored. Examples are the floppy disks, optical discs, hard disks
Access time
The average time lag between a request for information stored on a particular component, such as the hard drive or RAM, and its delivery.

Access time is slower with storage devices (microseconds) than memory (nanoseconds).
Hard disk
a storage device, that uses magnetic particles to store date
Characteristics of Hard disks
  • one bit capacity;
  • it is determine from whether it uses longitudinal or perpendicular recording,
  • platters
  • read/write heads
  • cylinders
  • sectors and tracks
  • revolution per minutes
  • transfer rate
  • access times
Track
a narrow recording hand that forms a full circle on the surface of the disk
Sector
break the track into small arcs
Cluster
the smallest unit of disk space that stores information
Platter
made up alluminum glass or ceramic made coated with alloy material that allows it to be recorded magnetically
Read and write
Reads items and writes items in the drives as it barely touches the disk surface
Cylinder
is the vertical section of a track that passes through platters
Revolutuion per minute
allows nearly instant access to all tracks and sectors on the platter
Head crash
when a read /write head touches the surfaces of a platter which leads to a loss of data and or information
RAID

NAS

SATA


EIDE

SCSI

SAS
redundant array of independent disks

Network Attach Storage

serial advanced technology attachment

enhanced integrated drive electronics

small computer system interface

serial-attached SCSI
Hard Disk Interfaces
SATA, EIDE, SCSI, and SAS
Hard Disk Controller
controls the transfer of data, instructions and information from a disk to and from the system bus and other components in the computer
Flash memory
is a type of non-voliatile memory that can be erased electronically

solid State Drive
a storage device that uses flash memry to store data instructions and information
Advantages SSd over magnetic hard disk
access time is 80x faster
transfer rates of SSd is faster
SSd generate less heat
more durable
disadvantages SSd over magnetic hard disk
higher failure rate
more expensive
Memory Card
removable flash device
Steps of Memory Card
1. conductors makes contact with connectors allowing transfering of things
2. The notch prevents the card from slipping out
3. on request controller tranfers item stored on the flash memory chip, using registers for temporary storage
4. Some cards contain write protect switches to prevent erasing accidents.
USB Flash Drives
a flash memory devices that is plugged into a USB port.
Cloud Storage
is an internet service that provides storage to computer users



  • to acces files on the internet from any computer

How do Optical Discs store information?
Pits and lands in the middle layar of the disc
how is this information is recorded and read? (Optical disc)
a high powered laser creates pits
a low powered laser reads them by reflecting light through the bottom
CD-Rom
An optical disk that can only be read
CD-R

CD-RW
CD-R can write but not erase

CD-RW and rewrittable;the reliability of a CD-RW disc tends to drop if you keep rewriting on it.
Blu-Ray and DVD
DVDs and Blu-Ray Discs work similarly to CDs, with some minor technical details. A
DVD-R/DVD-RW


DVD+R/DVD+RW
DVD-R and DVD+R are different formats, but that they have basically the same capabilities (they're both recordable) - likewise for DVD-RW and DVD+RW (they're both rewritable).
Guaranteed Life Expectancy

Magnetic disk

Optical disk

Solid State Drives

Microfilm


3-5 years

5-10 years

50 years

100 years
Potential

Magnetic Disk

Opticals

Solid State Drives

Microfilm


20-30

50-100

140

500
USB

CD-ROM

CD- R

CD-RW
universal serial bus

compact disc read-only memory

compact disc recordable


compact disc rewritable
Sending Device
initiates instructions
Communications channel
the data, instructions or information travel
Receiving device
accepts the data from the sending device that travelled through the communications channel
Network topologies

This specifies the physical layout of the network, and what kind of hardware is used (as communications devices and channels).

Star, Ring and Bus
Star all networks connect to the center

Bus a single cable all computer and others devices connect

Ring a cable creates a loop with all devices and computer arranges along the ring.
Network Classifications
this specifies the size of their area of coverage. Types of network classifications are LAN, MAN, WAN

Local Area Network connects computers to devices in limited geographical area

Wide Area Network covers a large geographic area using communications channel

Metropolitain area network high speed connects LAN to WAN
Network Architectures
This determines how control over the network is distributed. Types of network architectures are Client/Server and Peer-to-Peer

P2P is when there is a connection of about 10 or less computers that equal responsibilities

Client Server is the controller of the network aka the host computer.  The clients rely on the host for resources.
Dedicated Server
perform a specific task and can be place with other dedicated servers to perform task
File Server
stores and manages files
Database server
stores and provides access to databases
Network Server
manages network traffice
Web Server
a computer that delivers requested Web pages to your computer
Intranet
an internal network that uses internet technologies
Extranet
allows customers or suppliers to access part of it's intranet
Token Ring
specifies that computers and devices on the network share or pass a special signal.

only one token exist per network

Ethernet
a network standard that specifies no central computer or device on the network should control when data is transmitted; that is eac nose attempts to transmit data when it determines the network is available to recieve communication
FTP

RSS

LAN

MAN

WAN

P2P

TCP/IP

Wi-Fi

UWB

IrDA

RFID

WiMAX
File Transfer Protocol

Really Simple Syndication

Local Area Network

Metropolitan Are Network

Wide Are Network

Peer to Peer

Transmission Control Protocol/Internet Protocol

Wireless Fidelity

Ultra WideBand

Infrared Data Association

Radio Frequency Identification

Worldwide Interoperability for Microwave Acess
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