1. Hardware
Storage devices

2. What are storage devices
Storage devices are used to hold data separately from the PC’s hard disk drive. Data stored in this way can be retrieved later if required.
Floppy disks were originally used for backing up a disk drive, but the storage capacity of a modern PC has now made this an impractical option.
Alternative storage devices include the following:
CD-ROMs (Compact Disk- Read Only Memory)
CD-Rs (Compact Disk-Recordable)
CD-RWs (Compact Disk-ReWritable)
DVD (Digital Versatile Disk)

3. Storage devices: capability
How the storage device works
CD-ROMs
(read only)
Small plastic optical disks that typically store 700MB data (incl. Multimedia) using laser technology e.g. software.
CD-Rs
(write once)
Compact disks can hold 650MB. Data is written, and can be read by other PCs.
CD-RWs
(re-usable)
Used in a similar way to floppy disks, but holds up to 650MB.
DVD
(digital versatile)
Relatively new technology, developed in the 1990s. Holds 17GB – that’s around 25 CD-ROMS.

4. What are the drawbacks of these storage devices?
Try to think of one disadvantage for each storage device and write it down.
CD-ROMs (read only)
CD-Rs (write once)
CD-RWs (re-usable)
DVD (digital versatile)

5. Storage devices: limitations
Possible limitations
CD-ROMs
(read only)
Good for storage (high capacity) but data can only be read I.e. the disk cannot be used for recording.
CD-Rs
(write once)
As above, but can only be recorded once and never altered.
CD-RWs
(re-usable)
Data can be recorded, deleted and re-recorded, so subject to accidental error.
DVD
(digital versatile)
DVD-R (recordable) and DVD-RW (re-writable) are available, but capacity is reduced; still relatively expensive.