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Chapter 3: Storage Devices & Media

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• Solid State controls movements of electrons within a microchip

• Optical uses precision lasers to access data

• Magnetic uses magnetic patterns to access data

Types of Storage Media

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Types of Storage Devices

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Fixed Hard Disk

• Used to store operating system and working data

• Used for storing app software that needs fast retrieval

• Used by real-time systems and online systems

• Used in file servers for computer networks

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Portable Hard Disk Drives• Used as back-up to prevent data loss

• Used to transfer data, files and software between computers

Advantages Disadvantages

• Data access time/transfer rate is very fast

• Large memory capacities• Used as method of

transferring information between computers

• Easily damaged if user accidentally drops it or fails to shut it down correctly

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Floppy Disk Drives

• Used where small files need to be transferred or stored (i.e. word documents)

• Still used by older computer systems

Advantages Disadvantages

• Efficient use of space; using CDs would be more wasteful

• Cheap

• Very low memory capacity compared to CD/DVDs

• Few modern computers have floppy disk drives

• Data transfer is slow• Not very robust

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Magnetic Tapes

• Used in apps where batch processing is used (i.e. utility billing, bank checks)

• Used as back-up media since all data needs to be stored

Advantages Disadvantages

• Cheaper than equivalent-capacity hard disk

• Robust technology• Date transfer rate is fast

• Access time is slow• Another tape is required to

update info

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CD-ROM/DVD-ROM

• CD-ROMs are used to store music files, software, and computer games

• DVD-ROMs are used to store films

Advantages Disadvantages

• Hold far more data than floppy disks

• Cheaper than hard disk drive systems

• Data transfer rate/data access time are slower than hard disks

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CD-RW/DVD-RW

• CD-RWs/DVD-RWs are used to record radio/TV programs, but can be rewritten.

• Used in CCTV systems

Advantages Disadvantages

• Can be reused many times• Use diff. file formats each

time• Less wasteful because more

data can be added later

• Relatively expensive• Possible to accidentally

overwrite data

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Blu-Ray Disks

• Used in home video consoles

• Store and play back films (about 25 GB for 1)

• PCs can use it for data storage or backup

Advantages Disadvantages

• Very large storage capacity• Ideal for storing HD films• Fast data transfer rate• Data access speed is greater

than with other optical media

• Disks are relatively expensive

• Lack of encryption (at time of writing)

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Memory Sticks/Pen Drives• Used for backup or file transport

• Used as security devices

Advantages Disadvantages

• Compact and portable• Robust

• Impossible to protect data and files

• Easy to lose

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Flash Memory Cards

• Used to store digital camera photos/MP3 music

• Used as memory cards on mobile phones

• Used as backup in handheld computer devicesAdvantages Disadvantages

• Compact and portable• Robust• Use solid state memories

• Expensive per GB of memory when compared to hard drive disks

• Lower storage capacity than hard disks

• Finite number of times they can be read/written