Storage device 16 29 56 Secondary storage Backup

Storage device 16: 29: 56

Secondary storage Backup storage 16: 29: 56

Storage devices Storage device or backup device is used to store data and programs that are needed to be used again and again; e. g. Floppy, hard disks, CDs are often used as backing storage as well. 16: 29: 56

Type of secondary storage device • Magnetic storage devices • Optical storage devices • Semiconductor backup devices 16: 29: 56

Magnetic storage devices • Hard disk • Floppy disk • Zip drive • Magnetic tape 16: 29: 56

Hard disk 16: 29: 57

Hard disk Advantages • Main backing storage of files and programs Disadvantages • Slow to access data when compared to RAM • Can store a lot of data compared to floppy disk • Data can be damaged if the head crashes onto the platter • Can have a second hard disk as Back up storage 16: 29: 57

Floppy disk 16: 29: 57

Floppy disk Advantages • Small, thin and lightweight, so easy to carry around • Can be reused. But data can not be overwritten only deleted to create space 16: 29: 57 Disadvantages • Can not store that much e. g one big picture will take up a lot of space of the entire floppy • It is thin so it can be damaged easily

Zip disc/disk 16: 29: 57

Zip disk/disc Advantages • Can hold more data tha a floppy disk Disadvantages • Much more expensive than a floppy • Easy to carry around because of the size • You can need a special drive to read the disk 16: 29: 58

Magnetic Tape 16: 29: 59

Magnetic Tape Advantages • Can store a lot of data • Not easily damaged • Can be used overnight to back up a system 16: 29: 59 Disadvantages • Takes a long time to load data onto it • Have to go through the tape to get the data you want (cf serial access)

Optical storage CD ROM CD R/W DVD 16: 29: 59

CD - Rom Advantages • Data can not be erasedyou can not loss your data • Easy to carry around • Cheap to produce • Can be read by a DVD drive 16: 30: 00 Disadvantages • Fragile • Can scratch easily-this affects the data when the laser reads it • Slower to access than a hard disk

CD - RW Advantages • Data can be erased-it is possible to reuse it • Data can be updated – data can be rewritable again • Easy to carry around • Cheap to produce • Ca be read by a DVD drive 16: 30: 00 Disadvantages • Fragile • Can scratch easily-this affects the data when the laser reads it • Slower to access than a hard disk

DVD Advantages • Can store large amount of data Disadvantages • Does not work in CD ROM drives • Does not transmit virus • More expensive than CD ROMs • Good for storing films and videos • The prices are getting cheaper 16: 30: 00

Semiconductor/ Solid state storage devices e. g. Flash disk 16: 30: 01

Flash disk Data is stored by charging smallscale “batteries” on the device Most flash disks have a capacity of 256 Megabytes up to 8 Gigabytes 16: 30: 01