2. Standard Grade Computing STORAGE DEVICES CHAPTER 18 COMPUTER STUDIES Standard Grade

3. Standard Grade Computing Magnetic tape Hard disc Floppy disc Foundation BACKING STORAGE Permanent storage for data & programs so they are not lost when the computer is switched off. Examples of storage media are: CD -ROM –RW -R DVD-ROM –RW -R USB flash ROM (memory stick)

4. Standard Grade Computing STORAGE MEDIA MAGNETIC TAPE: Digital Audio Tape (DAT) is used to back up a hard disc i.e. high capacity but slow data access (sequential). FLOPPY DISC: Must be formatted first. Good for text storage as small capacity. Fast access i.e. direct /random. HARD DISC: Non removable with high capacity & fast data access (direct / random). Foundation

5. Standard Grade Computing COMPACT DISC Read Only Memory (ROM): data stored by the manufacturer & cannot be altered. Recordable (R): Data saved once then becomes permanent i.e. CD-ROM Rewriteable (RW): data can be saved, deleted updated but the user Optical data storage with random/direct access. High capacity good for graphics etc RETURN TO DVD SLIDE Foundation

6. Standard Grade Computing Digital Video Disc Read Only Memory (ROM) Recordable (R) Rewriteable (RW) Optical data storage with random/direct access. High capacity good for movies, TV programmes USB flash ROM (memory stick) A solid state storage device made up of flash ROM and connects via the USB interface. Foundation Click here for more details

7. Standard Grade Computing Backing Storage Comparison General MediaSpeed (Data Transfer) Cost £ (Approx) Capacity Magnetic Tape (DAT)Sequential – slow£20 - £10010 – 100Gb Floppy DiskDirect – slow£0.101.44 Mb Hard DiskDirect – fast£50 - £50020Gb – 1Tb CD - ROMDirect - mediumDepends on contents 650 or 700Mb (70/80 minutes audio) CD - RDirect - medium£0.25650 or 700Mb CD - RWDirect - medium£1650 or 700Mb DVD - ROMDirect - mediumDepends on contents 4.7 - 17Gb DVD - RDirect - medium£54.7Gb DVD - RWDirect - medium£104.7 – 9.4Gb USB Flash ROMDirect - medium/fast£10 - £20016Mb – 1Gb

8. Standard Grade Computing Each application package requires storage i.e. 1.Space on the hard disc for the package itself - Fixed when installed but changes if updated 2.Space for the files & data produced Text files are small. The file size increases greatly as Graphics Sound Animation etc are added. Application Backing Storage Credit

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10. Standard Grade Computing Formatting a Floppy Disc A floppy disc has to be set up for a particular computer system –FORMATTING e.g. PC vs Mac Formatting produces invisible tracks & sectors on the surface. Data is stored in blocks with a directory placed at the start. BEWARE: It will wipe ALL data from a disk. http://www.kelso.scotborders.sch.uk/departments/computing/sg_int2.htm CLICK HERE TO RETURN TO SLIDE SHOW