IGCSE Theory Section 3-Storage devices and media

Section 3: Storage devices and media
Candidates should be able to:
(a)  describe common backing storage media (including magnetic tapes, hard discs, all forms of CD and
DVD, memory sticks, flash memory) and their associated devices
(b)  identify typical uses of the storage media, including types of access (e.g. serial/sequential, direct/
random) and access speeds

• Fixed hard discs Used to store operating systems, software and working data.  Any application which requires very fast access to data for both reading and writing to.  Not for applications which need portability.  Used for online and real time processes requiring direct access.  Used in file servers for computer networks
• Portable hard discs Used to store very large files which need transporting from one computer to another and price is not an issue.  More expensive than other forms of removable media
• Magnetic tapes Any application which requires extremely large storage capacity and speed of access is not an issue.  Uses serial access for reading and writing.  Used for backups of file servers for computer networks.  Used in a variety of batch processing applications such as reading of bank cheques, payroll processing and general stock control
• Optical backing storage media such as CDs and DVDs CDs tend to be used for large files (but smaller than 1Gb) which are too big for a floppy disc to hold such as music and general animation.  DVDs are used to hold very large files (several Gb) such as films.  Both CDs and DVDs are portable i.e. they can be transported from one computer to another.  Both can be used to store computer data
• CD ROM/DVD ROM Applications which require the prevention of deletion of data, accidental or otherwise.  CDs used by software companies for distributing software programs and data; by music companies for distributing music albums and by book publishers for distributing encyclopaedias, reference books etc.  DVDs used by film distributors
• CD R/DVD R Applications which require a single eburningf of data, e.g. CDs Z recording of music downloads from the internet, recording of music from MP3 format, recording of data for archiving or backup purposes.  
• DVDs Z recording of films and television programs
• CD RW/DVD RW Applications which require the updating of information and ability to record over old data.  Not suitable for music recording but is very useful for keeping generations of files.  DVDs have between five and ten times the capacity of CDs
• DVD RAM Same properties as DVD RW but quicker access and data can be overwritten more easily.  Similar to floppies in nature but has 3000Z6000 times more storage and uses optical technology
• Blu-ray Capacities of 25Gb, 50Gb and 100 Gb.  Used for storing films (movies). 25Gb equates to 2 hrs HDTV, 13hrs standard definition TV.  It is possible to playback video on a disc while simultaneously recording HD video.  (Will be) used for storage of PC data
• Solid state backing storage Smallest form of memory, used as removable storage.  More robust than other forms of storage.  More expensive than other forms, but can be easily written to and updated
• Memory sticks/Pen drives Can store up to many Gb.  Used to transport files and backup data from computer to computer
• Flash memory cards Used in digital cameras, palmtops, mobile phones, MP3 players

IGCSE Theory Section 2-Input and Output Devices

Section 2: Input and output devices-

Candidates should be able to:
(a)  identify the following input devices:
   keyboards, numeric keypads, pointing devices (including mouse, touch pad and tracker ball), remote
controls, joysticks, touch screens, magnetic stripe readers, chip readers, PIN pads, scanners, digital
cameras, microphones, sensors, graphics tablet, MICR, OMR, OCR, barcode readers, video cameras,
web cams, light pens
(b) identify suitable uses of the input devices stating the advantages and disadvantages of each:

• Numeric keypad Applications where only numeric data is to be entered.  Inserting personal identification number (PIN) for Chip and PIN credit/debit cards, or when using an ATM machine to withdraw money or check a bank balance
• Pointing devices Z all All applications which require selection from a graphical user interface.  For example: the selection of data from a set list or menu
• Trackerball For use by people with limited motor skills e.g. young children or people with disabilities
• Magnetic stripe readers At POS terminals, ATMs and in security applications
• Chip readers and PIN pads Payment cards, ID cards, door control systems, public transport tickets
• Optical Mark Reader Inputting pencil marks on a form such as a school register, candidate exam answers, any application involving input of a choice of options 
• Optical Character Reader Inputting text to a computer ready for processing by another software package such as word processors, spreadsheets, databases etc.
• Light pen Where desktop space is limited, it is used instead of a mouse or for drawing applications where a graphics tablet might be too big, for more information : http://en.wikipedia.org/wiki/Light_pen
• CRT monitor Applications where space is not a problem.  Applications where more than one user may need to view screen simultaneously such as in design use, e.g. when several designers may need to offer suggestions on a prototype
• TFT monitor Applications where space is limited such as small offices.  Applications where only one person needs to view the screen such as individual workstations
• Laser printer Applications which require low noise and low chemical emissions, e.g. most networked systems.  Applications which require rapid, high quality and high volumes of output, e.g. most offices and schools
• Inkjet printer Applications which require portability and low volume output, where changing cartridges is not an issue e.g. small offices and stand alone systems.  Applications which require very high quality output and where speed is not an issue, e.g. digital camera applications
• Dot matrix printer Applications where noise is not an issue and copies have to be made, e.g. industrial environments (multipart forms, continuous stationery, labels etc.), car sales and repair companies, manufacturing sites
• Graph plotter CAD applications, particularly where large printouts are required such as A0 

IG theory

Hardware


The physical components of a system

Software 

Set of commands that are processed for an output. For example utility software which is used to change the system (control panel or system preferences). Application software such as Word Processing and Call of Duty. The operating system is also software, it is used so everything such as the printer and word can function and work together.  

Components

Input devices: CPU (central processing unit), ROM (read only memory) is non volatile and is permanent, RAM (random access memory) holds what you are currently doing such as playing a game, it's continously changing and is volatile. RAM and ROM are primary memory, secondary storage is the hard drive.
Output devices: Printers such as laser. 

Interface

GUI's (graphical user interface)  are WIMP's (windows, icons, menu's, pointers) and Command line interface.

Vocabulary

Desktop- PC

Server- Mainframe, accessed bulk processing and storage

Palm top 

PDA- personal digital assistance (not a phone)