3.1 Storage devices and media Revision

Think about what we store on our computers 3.1 Storage devices and media What is data Storage Storage means putting data into a known place so we can come back to it We say that we can: Write Data (saving) Read Data (opening) Think about what we store on our computers

Main Memory Vs Backing Storage 3.1 Storage devices and media Main Memory Vs Backing Storage Main Memory Backing Storage Sometimes known as Internal Memory or primary memory Backing storage some known as secondary storage Includes RAM and ROM Name for all other storage devices as part of a computer like hard drive Usually used to store data temporarily (in the case of RAM) Usually used to store data over a long time Usually used to store data while it is being processed by the CPU Usually used to store application software, operating system software, files etc Is volatile – means data will be lost if computer is turned off Non-volatile - Means data will not be lost of computer is turned off.

Storage device – reads the data from the storage medium 3.1 Storage devices and media Storage Media & Devices Storage medium is the name given to the device that actually holds the data Storage device – reads the data from the storage medium Sometimes the storage medium is fixed (permanent) i.e. magnetic coated disks build into hard drive Sometimes the storage medium is removable from the device i.e. CD ROM that can be taken out of the drive

Serial/Sequential Access 3.1 Storage devices and media Serial/Sequential Access Serial (sequential Access) Direct (Random Access) Files are stored one by one in a sequence Stores files so that they can instantly be accessed Must search through the files one by one until you get to the one you want No need to search through files to get to the one you want Example: VHS tape, Cassette Tape, Magnetic Tape Example: DVD, CD ROM, Blu-ray, external hard drive, flash drive Remember: Serial: With a cassette you have to fast forward to get to a specific point. Direct: You can skip to a particular scene with a DVD.

Increase in storage capacity 3.1 Storage devices and media Data Storage Capacity Data storage devices are have very different capacities. Some Can store large amounts of data while others can store lots: Floppy Disk 1.4MB CD-ROM 700MB DVD 4.7GB Blu-Ray 25 GB – 128GB Hard Drive 8 TB Increase in storage capacity Magnetic Tape Up to 185 TB 

3.1 Storage devices and media Magnetic Storage Devices Magnetic storage media and devices store data in the form of tiny magnetised dots. These dots are created, read and erased using magnetic fields created by very tiny electromagnets. In the case of magnetic tape the dots are arranged along the length of a long plastic strip which has been coated with a magnetisable layer (audio and video tapes use a similar technology).

Storage Access Speeds Portability Access Type Durability Use 3.1 Storage devices and media Magnetic Storage - Hard Drives: fixed and Portable Storage Very large capacity – even up to several terabits Access Speeds Random Access - so very fast access speeds Portability Fixed Hard drive – not portable Portable Hard Drive – can move data from one computer to another Access Type Random (Direct) access Durability Fixed – less likely to break as fewer accidents can occur Portable – more likely to break being carried out Use Fixed – is the main backing storage device used by all computers

Storage Access Speeds Portability Access Type Durability Use 3.1 Storage devices and media Magnetic Storage: Magnetic Tape Storage Very large capacity – more than magnetic hard drives Access Speeds Serial Access – so slow compared with magnetic hard drives Portability Backed up magnetic tapes are normally stored away in a fire proof safe Access Type Serial Access Durability Quite durable as normally kept in a safe place Use Usually used to back up data stored on networks Normally cheaper to store data per bite compared with magnetic disks

Magnetic tape uses 'serial access' to find a piece of data. 3.1 Storage devices and media Magnetic Storage: Magnetic Tape Many organization's, such as your school or an office, need to back up large volumes of data each day. Large organizations who need to back up their systems daily tend to use magnetic tapes to store their data. Magnetic tape uses 'serial access' to find a piece of data. This means that to find a specific piece of data, the tape reader has to start at the beginning of the tape and continue fast forwarding until it gets to the piece of data that needed.

A Laser beam is the usual light source. 3.1 Storage devices and media Optical Media Optical storage devices are devices that save data as patterns or dots. A Laser beam is the usual light source. Data is read by bouncing the laser beam off the surface off the medium. A Laser can also be used to write (make dots) which is otherwise known as burning.

Name CD ROM DVD ROM Blu-Ray Storage Access Type Use 3.1 Storage devices and media Optical Media Name CD ROM DVD ROM Blu-Ray Storage 700MB 4.7GB 20-128GB Access Type Random Access Use Audio CDs Low quality movies Small Applications/games High quality movie Software Games High-definition video (1080p) High-definition audio Stereoscopic 3D PlayStation 3 games PlayStation 4 games Xbox One games

CD-R and DVD-R You can write to the CD/DVD but not erase anything 3.1 Storage devices and media Optical Media - R – Read and W-Write CD-R and DVD-R You can write to the CD/DVD but not erase anything Use the CD/DVD until they become full CD-RW and DVD-RW You can read and write to the CD/DVD – add and delete data as often as you like DVD RAM Very reliable and used to store movies for a long time Used in many camcorders and comes with a special protective case

The term ‘solid-state’ essentially means ‘no moving parts’. 3.1 Storage devices and media Solid ‘state’ The term ‘solid-state’ essentially means ‘no moving parts’.  Solid-state storage devices are based on electronic circuits with no moving parts (no reels of tape, no spinning discs, no laser beams, etc.) Solid-state storage devices store data using a special type of memory called flash memory...

Device Access Type Capacity Use Notes Solid ‘state’ 3.1 Storage devices and media Solid ‘state’ Device USB Memory stick Memory Card Smart Card Access Type RANDOM Capacity Up to 128GB 64GB Small but more that magnetic strip Use Used to store computer files Used in phones a cameras Used Satellite TV cards, and modern credit cards at Chip-and-pin terminals Notes More robust (strong) that memory and smart cards Easily lost and easily broken

You could delete a file by accident Your computer could break down 3.1 Storage devices and media Backups Backup means making one or more copies of your data in case you lose your data? Why? You could delete a file by accident Your computer could break down Your computer could get infected by a virus which could edit data Your laptop is stolen or becomes damaged Most businesses use computers to store very important data (customer records, financial information, designs for products, etc.) If this data is lost, the business could possibly have to close. Backing-up business data is essential.

Personal backups of the data on your hard-drive can be made by… 3.1 Storage devices and media How are Backups created Personal backups of the data on your hard-drive can be made by… Burning files to a CD-R Copying files to an external hard-drive Copying the files to another computer on a network Business backup data by: Making copies of data very regularly Using large-capacity media such as magnetic tape Keeping old copies of backups, just in case Automating the system so that nobody forgets to do it! Keeping backup media off-site (in case of fire or theft)