STORAGE DEVICES Storage devices are categorized by the method they use to store files.

Magnetic Storage

Magnetic Storage Devices  Magnetic storage use oxide-coated plastic storage media called mylar.  Small magnetic spots represent binary data on regions of a rotating surface. They are read by a small magnet head the moves across the surface.  Common magnetic storage devices are floppy disk drives, hard disk drives, and tape drives.

Magnetic Data Storage Network Server One type of storage is on a network server. The network server is a central computer in a network that contains the programs that the various workstations share. It is also a place to save your work. Your folder is on the network and you can access that folder on the network from anywhere in the school district on a computer in which you are logged in. A sample of a network server

Magnetic tape is another magnetic storage device. Magnetic tape provides inexpensive archival storage for large quantities of data. Tape storage is much too slow to be used for day-to-day computer tasks. Disadvantage – Magnetic tape has serial access that means it is searched from beginning to end, not randomly. It is therefore, slower when searching for data. When are they useful? MMagnetic tape is used to make backup copies of data stored on hard disk drives. It can hold up to 1 TB of data! FFor example, back-up copies of the information stored on our school’s network drive is periodically saved onto magnetic tape. Magnetic Data Storage Magnetic Tape

Magnetic Data Storage Hard Disk Drives A Hard Disk Drive is the main internal backing storage. It stores applications used by the computer. It contain several iron oxide-covered metal platters that are usually sealed in a case inside computers. The main benefit of hard drives is that they have a large storage capacity. Most hard drives installed in a computer would have 120 gigabytes. Disadvantages would be that it generates a lot of heat, has a low resistance to shock, and if data is lost it is very difficult to recover.

Floppy disks are one type of external backing storage. They are flat circles of iron oxide- coated plastic enclosed in a hard plastic case. They are sometimes called 3 1/2” disks because the size of the hard plastic case. Disks only store up to 1.44 Mb of data and are becoming outdated. When are they useful? EExcellent for transferring small files of data from one machine to another and for backing up important small files stored on your hard disk. Magnetic Data Storage Floppy Disks 5 ¼ floppy – RETRO!

Optical Storage

Optical Storage Devices Optical storage devices use laser technology to read and write data on silver platters. Optical storage records binary data as a trail of tiny pits burned on the disc surface using a laser beam. The data that these pits represent can be ‘read’ with a beam of laser light. Common optical storage devices are CDs and DVDs.

CD-ROM (Compact Disk Read Only Memory) disks are optical disks that use the same technology as musical compact disks. They store about 650 Mb of data which is equal to more than 450 floppy disks. What can they be used for? CCD-ROMs are much bigger than floppy disks. Therefore, they can be used for large multimedia files such as PowerPoint files. TThey can also store pictures, sounds and video clips. Optical Data Storage Compact Disks

DVDs (Digital Video Disks) are optical disks that are the same size as CD-ROMs. They store up to 9.4 Gb of data, depending on whether data is stored on one or two sides of the disks, and how many layers of data each side contains. What can they be used for? DDVDs can be used for very large multimedia files such as full length movies. Any disadvantages? They can be scratched or broken easily. Optical Data Storage Digital Video Disks

CD-ROMs are for “read-only” access, meaning you cannot use them to record or store your own data. Unfortunately, you can only read what is stored on them and can not use them for saving. If you want to record on a CD, you need a CD-R disk (compact disk recordable). Once data is recorded on a CD-R, you cannot erase or modify it, just add more data. Optical Data Storage Erasing and Rewriting

A CD-RW (compact disk rewritable) is designed so you can write data and continue to access and modify the data. Therefore, you can save files over and over again on the same CD. They also generally store the same amount as a CD – 650 Mb. This is generally not enough for saving a video or movie though. Recordable and rewriteable DVDs are also available. DVD-R is recordable. DVD-RW is rewritable.

CDs A CD-ROM is portable read- only memory A microscopic pit on a CD represents a binary 1 and a smooth area represents a binary 0 A CD-Recordable (CD-R) drive can be used to write information to a CD once A CD-Rewritable (CD-RW) can be erased and reused The speed of a CD drive describes how fast it can write information to a CD-R (24x), a CD-RW (10x), and how fast it can read (40x) Compact Disc DVDs A DVD is the same size as a CD, but can store much more information The format of a DVD stores more bits per square inch A CD can store 650 MB, while a standard DVD can store 4.7 GB  A double sided DVD can store 9.4 GB  Other advanced techniques can bring the capacity up to 17.0 GB There are various recordable DVD technologies Digital Versatile Disc or Digital Video Disc vs.

Solid State Storage

Solid State Flash Storage Devices Solid-state flash storage devices are small cards enclosed in hard plastic. They store binary data in electronic circuits. They are similar to ROM memory, except that they can be erased so that new data can be stored on them. Data is stored on flash storage devices by slipping physical switches on an integrated circuit. The switches can be moved after they are set so that you an erase and then rewrite data on a flash storage devices.

Flash storage devices are also called flash drives, thumb drives, removable drives, or USB drives. Flash drives plug directly into the USB port of a personal computer and require no additional cables or software installation. Unfortunately, they can easily be lost. Flash drives for computers can hold from 32 Mb to 6 Gb of data. What can they be used for? FFlash drives are commonly used for storing and transferring data for computer files, graphics, and digital cameras. Solid State - Flash Storage Flash Storage Devices

Storage Capacity Equivalents

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