Types of Computers

Introduction to Storage Devices

Storage Devices

• Used to keep data when the power to the computer is turned off.
• Medium/media
• Location where data is stored.

Hard Disk

• Usually mounted inside the computer’s system unit.
• Can store billions of characters of data.
• Stated in forms of bytes:
• Megabytes, Gigabytes or Terabytes

Magnetic Storage

• Recording of data onto disks or tape by magnetizing particles of an oxide based surface coating.
• A fairly permanent type of storage that can be modified.
• Used by mainframe or microcomputers

Floppy Disk

• Round piece of flexible Mylar plastic covered with a thin layer of magnetic oxide and sealed inside a protective covering.
• May be referred to as a “floppy”
• 3½ disk capacity is 1.44 MB or 1,440,000 bytes

Solid-State Storage

• Flash memory cards
• Widely used in notebook computers
• Used to record MP3 music files
• Key chain hard drives
• Key chain flash memory devices
• Connects to a USB port

Optical Storage

• Means of recording data as light and dark spots on CD or DVD.
• Reading is done through a low-power laser light.
• Pits
• Dark spots
• Lands
• Lighter, non-spotted surface areas

CD-ROM

• “CD – Read Only Memory”
• Also called CD-R
• CD-Read
• Storage device that uses laser technology to read data that is permanently stored on compact disks, cannot be used to write data to a disk.

CD-RW

• “CD-Read Write”
• A storage device that reads data from CD’s and also can write data to CD’s.
• Similar to a CD-ROM, but has the ability to write to CD.

DVD

• DVD ROM
• Digital Video Disk which is read only.
• DVD-R
• Digital Video Disk which can be written to one time. It then becomes read only.
• DVD-RW
• Digital Video Disk which can be rewritten to.

Blu-Ray Technology

• New standard in storage
• Blu-Ray
• New disks use blue laser light instead of the red laser light used in traditional CD players
• Disks may ultimately hold
• Over 30GB on one-sided disks
• Over 50GB on two-sided disks

Flash or Jump Drives

• External storage devices that can be used like a external hard drive.
• They have the capability to be saved to, deleted from, and files can be renamed just like with a normal hard drive.

Hot Swappable

• A hot swappable device is one which can be replaced whilst the server is still in operation.
• You should only hot swap components when the component and operating system supports it.
• The following components can be hot swapped: RAM, disk drive, power supply, NIC, graphics cards.
• Hot swappable components are more expensive. Often only necessary when you need to keep a server operational 24/7.

List of Devices for Secondary Storage

• Magnetic tape and disks
• Compact Disk Read-Only Memory (CD-ROM)
• Write Once Read Many - (WORM)
• Magneto-optical disks
• Redundant Array of Inexpensive Disks (RAID)
• Optical disks
• Digital Video Disks
• Memory cards
• Flash memory
• Removable storage

References

• Computing Essentials 2005
• M. Guymon. Pleasant Grove High School