 5.3.1 Other storage media
| Revision Points: (Full course) |
Candidates are expected to be able to:
- identify a range of storage devices or media additional to those listed in 5.1.3 i.e. DVD, CD-R, CD-RW and Zip drives;
- describe situations when each of the devices/media above may be used;
- describe the comparative advantages and disadvantages of using storage media identified above and in 5.1.3
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 Other Magnetic Storage media:
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Zip and Jaz drives are similar to floppy drives because the individual disks are removable and portable but they hold much larger amounts of data (typically between 100 MB and 2 GB).
- Advantages: Portable media, relatively cheap, good for archiving data.
- Disadvantages: Not a compact as USB flash-drives, can be damaged, slow data transfer compared to modern alternatives.
Other Optical Storage media:
Digital Versatile/Video Disc (DVD):
- DVD drives are now replacing CD drives in computers due to the huge memory capacity of the disk and the high quality of stored images. A DVD single sided, single layer DVD can store up to 4.7 GB of data, the equivalent of 26 CD-ROMS. This means full-motion films with sound tracks and subtitles in multiple languages can easily be stored on one DVD disk.
- Advantages: a film stored on a DVD has significant advantages over magnetic VHS video tape because the digital images and sound tracks are of a higher quality and do not deteriorate with constant use. The user can also move to any part of the film immediately (random access). DVD-RW drives (writable drives) are relatively cheap now and will soon replace VHS tapes as a way of recording films.
- Disadvantages: easily damaged by being scratched.
Recordable Compact Disk media
- CD-R - these CDs are initially blank but you can use a special read/write CD drive unit to store programs and data onto the disc but they can only be written to once.
- Advantages: Very cheap way to store data. Not damaged by magnetic fields or water.
- Disadvantages: The data cannot be edited once it has been written to the CD-R. Easily damaged by being scratched.
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CD-RW - these are similar to the ‘R’ type above but you can read, write and delete files from the disc many times, just like a hard disk.
- Advantages: As for CD-R plus the ability to re-write and erase data so they can be used again.
- Disadvantages: Easily damaged by being scratched.
- Both CD-ROMs and CD-Rs can be referred to as WORM devices. This stands for Write Once Read Many times.
| Comparing storage devices: |
Storage
capacity |
1 CD-ROM (650 MB) = 451 Floppy disks (1.44 MB)
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1 DVD (4.7 GB) = 7 CD-ROM's (650 MB)
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Access
speed |
Harddrive |
CD-ROM |
Floppy disk |
| 1000 KB/s |
100 KB/s |
36 KB/s |
Other ways data can be stored:
Magnetic strips - a strip of magnetic tape built into a plastic cards can store a small amount of data. Phone cards, debit cards and library cards can be written to so changes in the data can be stored.
Smart cards - a processing microchip built into a plastic card can store data as well as processing information. The SIM card used in a mobile phone stores phone numbers and names as well as allowing providing a menu of options and allowing you to connect to your service provider.
 Memory cards - there are used in a wide range of applications to store data. Typical examples include Compact FlashTM and SmartmediaTM memory cards which are used in digital cameras. They can have capacities of over 1 GB and a memory card reader or floppy disk adapter can be used to transfer the data to a computer.
ROM (Read Only Memory) - chips are used to store the permanent operating system data (the BIOS). In some types of computer, such as a pocket book, they may be used to store major programs such as a word processor. They are however more difficult to replace when a new version is released. They are also used to store the permanent programming inside a domestic device such as a television or washing machine.
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