F-COMP 002 Computers Papakonstantinou Koula www.casacollege.com/library/ Assessments • • • • Midterm Assignment Projects Homework 40 % • Final exam 60 % Computer Lab rules Eat and drink OUTSIDE the lab Be careful handling computers Make sure you listen the directions Open only your work Never delete, rename or remove anything from the computer unless directed by teacher Do not change any computer settings Remain seated and work quietly Types and components of computers What is a computer? A computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve, and process data. Computer is used to type documents, send email, play games, and browse the Web. Computer is used it to edit or create spreadsheets, presentations, and even videos. What is Hardware? Hardware is the physical parts of the computer system – the parts that you can touch and see. What is software? Software is a collection of instructions that can be ‘run’ on a computer. These instructions tell the computer what to do. Software is not a physical thing it is just a bunch of codes. Software Types Systems software Programs that allow the hardware to run properly e.g operating systems Applications software Programs that allow the user to do specific tasks e.g browser, spreadsheets Exercise Operating System Tasks of an operating system Controlling the operation of the input, output and backing storage devices Supervising the loading, running and storage of applications programs Dealing with errors that occur in applications programs Maintaining security of the whole computer system Maintaining a computer log Allowing communication between user and the operating system – user interface Graphical user interfaces Command line interfaces User interface Command line interfaces Require a user to type in instructions in order to choose options from menu Number of command to type in User has to learn a lot of commands just to carry out basic operations Graphical user interface User interacts with computer using pictures or symbols Menus Right click, left click Icons Buttons Types of Computers Supercomputers Fastest Most expensive Used for scientific and engineering applications Weather forecasting Mainframe computers Very powerful Can have hundreds of simultaneous users Used by large companies for data processing Networks servers on internet Personal Digital Assistants (PDAs) Small hand-held computers Use a touch screen Storing contacts information, keeping dairy, making notes, sending and receiving emails Palmtop devices Microcomputers Most common Desktop – Notebook Notebook computers Light and easy to carry around. No trailing wires Easy to steal Limited battery life Embedded computers Washing machines Telephones Cameras Input from a device’s sensors and output control the operation of the device Central heating system Computer System Input Process Data Storage Output Inputs Raw data fed into an information system Processing The way information systems convert raw data into useful information Storage Data is stored in an information system, so that it can be utilised when required. Outputs The visible or audible result of data processing. Information that can be used. Input devices Alphanumeric Keyboard A very common, general purpose, input device that allows text(abc…), numbers (123…) and symbols (%[email protected]) to be entered into a computer. A keyboard is simply a set of buttons. Each button has a symbol assigned. Numeric Keypad A small keyboard that only has numbers. Used to enter numeric data into computers such as those in ATMs. Most computer keyboards have a numeric keypad on the right side, and most mobile phones (there are also computers) have a one for entering phone numbers, etc. PIN Pad This is a device with a numeric keypad used to enter a person’s Personal Identity Number (PIN) e.g. when paying with a credit card. PIN pads are also found on electronic door locks – you enter a PIN to unlock the door. Mouse A pointing device found on most PCs. Sensors on the bottom of the mouse detect when the mouse is moved. Data about this movement is sent to the computer. Often used to control the pointer in a GUI. Touchpad A pointing device found on most laptops. Used instead of a mouse since it takes up less space. The user moves a finger across the touch pad and this movement data is sent to the computer. Usually used to control the pointer in a GUI. Trackball / Tracker Ball This pointing device is not moved about like a mouse, instead it has a large ball that the user spins. Data about which direction the ball is spun is passed to the computer. It can be used to control a GUI pointer. Tracker balls are often used by people with limited movement(disabled) or by the very young since they are easier to use than a mouse. Graphics Tablet A pointing device often used by designers and artists to allow natural hand movements to be input to graphics applications. A stylus is held like a pen and moved over the surface of the tablet. Data about the stylus movements are sent to the computer. Joystick / Joypad Used mainly for playing games. The user moves the joystick left/right, forward/back and data about these movements are sent to the computer. Small joysticks can also be found on some mobile phones. Scanner A device that ‘scans’ images, book pages, etc. Scanning is basically taking a close-up photograph (just very slowly and with great detail). The scanned image data is passed to the computer. Scanned images can be further processed once inside the computer, e.g. OCR of printed text. Digital Camera A device that captures digital photographs. Most digital cameras do not directly input data into a computer - they store photographs on memory cards. The photographs can later be transferred to a computer. A modern digital camera can capture 10 Megapixels or more per photograph - that’s 10,000,000 colored dots (pixels) in every photo! Web Cam This is a very basic video camera used to feed live video into a computer. The video data from a web cam is low quality compared to a full video camera. However it is good enough for web chats Usually a web cam is clipped to the top of a monitor, but many laptops now have web cams built into the edge of the screen. Microphone An input device that converts sound into a signal that can be fed into a computer. The signal from a microphone is usually analogue so, before it can be processed by a computer, it must be converted into digital data. An Analogue-to-Digital Convertor (ADC) is used for this (usually built into the computer’s sound card) Magnetic Strip Reader Many plastic cards, such as credit cards, have a strip of material that can be magnetised on the back. Data can be stored here in the form of magnetised dots. Usually the data stored on this strip in the same data shown on the front of the card (e.g. the credit card number, expiry date and customer name). The stripe allows this data to be input to a computer system faster and more accurately than by typing it in. A magnetic strip/stripe reader is used to read the data from the stripe. This is usually done by ‘swiping’ the card through a slot on the reader. Smart Card / 'Chip' Reader Modern credit cards and ID cards don’t use a magnetic strip. Instead they have a tiny ‘chip’ of computer memory embedded inside them. (These cards are often referred to as smart cards.) Data can be stored in this memory and read back using a ‘chip’ reader. A card is inserted into the reader where metal contacts connect to the metal pads on the front face of the card. The reader can then access the memory chip and the data stored on it. Smart cards can store much more data than magnetic strip cards, e.g. an ID smart card would store not only the owner’s name and card number, but might also have a digital image of the person. MICR Reader Magnetic Ink Character Recognition (MICR) is a technology that allows details from bank cheques to be read into a computer quickly and accurately. The cheque number and bank account number are printed at the bottom of each bank cheque in special magnetic ink using a special font. These numbers can be detected by an MICR reader. OMR Scanner Optical Mark Recognition (OMR) is a technology that allows the data from a multiple-choice type form to be read quickly and accurately into a computer. Special OMR forms are used which have spaces that can be colored in (usually using a pencil). These marks can then be detected by an OMR scanner. Common uses of OMR are multiple-choice exam answer sheets and lottery number forms. OCR Scanner Optical Character Recognition (OCR) is a software technology that can convert images of text into an actual text file that can then be edited (e.g. using wordprocessing software). The result is just as if the text had been typed in by hand. OCR is typically used after a page of a book has been scanned. The scanned image of the page is then analysed by the OCR software which looks for recognisable letter shapes and generates a matching text file. Barcode Reader / Scanner A barcode is simply a numeric code represented as a series of lines. These lines can be read by a barcode reader/scanner. The most common use of barcode readers is at Point-ofSale (POS) in a shop. The code for each item to be purchased needs to be entered into the computer. Reading the barcode is far quicker and more accurate than typing in each code using a keypad. Output devices Flat-Screen Monitor (TFT or LCD) Flat-screen monitors are light in weight and they take up very little desk space. Digital / Multimedia Projector Digital projectors are used in situations when a very large viewing area is required, for example during presentations, for advertising, or in your home for watching movies. A projector connects to a computer, a DVD player or a satellite receiver just like a ordinary monitor. The image is produced inside the device and then projected out through a large lens, using a powerful light source. Loudspeaker If you want to hear music or sounds from your computer, you will have to attach loudspeakers. They convert electrical signals into sound waves. Loudspeakers are essential for applications such as music editing, video conferencing, watching movies, etc. Dot Matrix Printer A dot-matrix printer is named after the pattern (a grid or ‘matrix’) of dots used when creating the paper printout. Dot-matrix print quality is poor The printers are noisy Dot matrix printers often use continuous stationary: long, continuous strips of paper Several ‘carbon-copies’ can be printed in one go. InkJet Printer Cheap, high-quality, full-color printing These printers have a similar print-head mechanism to a dot matrix printer. Several colored inks can be used to produce full-color printouts. Ink-jet printers are very quiet in use They are also cheap to manufacture and thus cheap to purchase The ink is very expensive to buy so the printers are expensive to use. Laser Printer Laser printers are very complex devices, and thus expensive to buy. They are very cheap to use. The laser and toner system allows very fast printing compared to other printers Laser printers are very common in offices since they print very quickly, are cheap to use and are reasonably quiet. Plotter Plotters are often used by designers and architects since they work with huge pieces of paper, far bigger than anything a normal printer could work with Input output devices Touch Screen A touch screen is an alternative to a separate pointing device. With a touch screen the user selects items on the screen by touching the surface. This makes touch screen systems very intuitive and simple to use. Often used for information terminals in public places e.g. libraries or museums where mice or keyboards may be stolen or damaged. Headphones with microphones Headphones with microphones are with chat and phone applications Computer activity Exercise 1 The block diagram represents the parts of a computer system. Which parts represent : A printer ……. A mouse or keyboard …… A disk drive ….. Exercise 2 Fashion Store is a high street shop selling clothing Give the name of TWO input devices that must be part of the shop’s work station Input device one ………… Input device two ……….. Give the name of TWO output devices that must be part of the shop’s system. Output device one …….. Output device two ……. Exercise 3 Tick true or false next to each of these statements. TRUE Input devices are examples of hardware A mainframe computer can’t be carried around Chip reader is a part of operating system Barcode reader is an output device Answers to multiple choice examination questions are recorded using an OCR sheet Spreadsheet software would be used to create a burglar alarm system MICR is used for reading data from the bar code on a food item Dot matrix printers are very noisy Laser printers are easy to use if continuous stationery is required Touch screen are examples of input-output device FALSE Exercise 4 Storage Devices and Media What is Data Storage? Putting the data in a known place. We can later come back to that place and get our data back again. ‘Writing’ data or ‘saving’ data are other ways of saying ‘storing’ data. ‘Reading’ data, ‘retrieving’ data or ‘opening’ a file are ways of saying that we are getting our data back from its storage location. Main Memory Main memory (sometimes known as internal memory or primary storage) is another name for RAM and ROM. Main memory is usually used to store data temporarily. It is volatile (this means that when power is switched off all of the data in the memory disappears). Main memory is used to store data whilst it is being processed by the CPU. Data can be put into memory, and read back from it, very quickly Backing Storage Backing storage is the name for all other data storage devices in a computer: hard-drive, etc. Backing storage is usually non-volatile, so it is generally used to store data for a long time. Storage Media & Devices The device that actually holds the data is known as the storage medium (‘media’ is the plural). The device that saves data onto the storage medium, or reads data from it, is known as the storage device. Sometimes the storage medium is a fixed (permanent) part of the storage device, e.g. the magnetic coated discs built into a hard drive Sometimes the storage medium is removable from the device, e.g. a CD-ROM can be taken out of a CD drive. Accessing Stored Data Serial / Sequential Access Direct / Random Access Serial / Sequential Access A serial (or sequential) access storage device is one that stores files one-by-one in a sequence. Systems that store things on tape (video, music, computer data, etc.) are always serial access Direct / Random Access A direct (or ‘random’) access storage device is one that stores files so that they can be instantly accessed - there is no need to search through other files to get to the one you want. Data Storage Capacity Data Storage Capacity Data storage capacity is measured in bytes (B). A thousand bytes is known as a kilobyte (kB) 1,000B = 1kB A million bytes is known as amegabyte (MB) 1,000,000B = 1MB A thousand million bytes is called a gigabyte (GB) 1,000,000,000B = 1GB A million million bytes is called a terabyte (TB) 1,000,000,000,000B = 1TB Magnetic Storage Devices Why Magnetic? 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. Hard Drives Hard-drives have a very large storage capacity (up to 1TB). They can be used to store vast amounts of data. Hard-drives are random access devices and can be used to store all types of films, including huge files such as movies. Data access speeds are very fast. Portable Hard Drive A portable hard-drive is one that is placed into a small case along with some electronics that allow the hard-drive to be accessed using a USB or similar connection. Portable hard-drives allow very large amounts of data to be transported from computer to computer. Magnetic Tape Magnetic tape is a large capacity, serial access medium. Because it is a serial access medium, accessing individual files on a tape is slow. Tapes are used where large amounts of data need to be stored, but where quick access to individual files is not required. A typical use is for data back-up (lots of data, but rarely only accessed in an emergency) Floppy Disc A removable, portable, cheap, low-capacity (1.44MB) storage medium. Floppy discs are random access devices used for transfer small amounts of data between computers, or to back-up small files, etc. Access times are slow. Zip Disc A removable and portable storage medium, similar in appearance to a floppy disk, but with a much higher capacity (100MB, 250MB or 750MB). Zip discs are random access devices which were used for data back-up or moving large files between computers. Jaz Disc A removable and portable storage medium based on hard-drive technology, with a large capacity (1GB or 2GB). Jaz discs are random access devices which were used for data back-up or moving large files between computers. Discs were expensive to buy and not very reliable. Optical Storage Devices Why 'Optical'? Optical storage devices save data as patterns of dots that can be read using light. A laser beam is the usual light source. The data on the storage medium is read by bouncing the laser beam off the surface of the medium. If the beam hits a dot it is reflected back differently to how it would be if there were no dot. This difference can be detected, so the data can be read. CD-ROM Compact Disc - Read-Only Memory (CD-ROM) discs can hold around800MB of data. The data cannot be altered (non-volatile), so cannot be accidently deleted. CD-ROMs are random-access devices. CD-ROMs are used to distribute all sorts of data: software (e.g. office applications or games), music, electronic books (e.g. an encyclopaedia with sound and video.) DVD-ROM Digital Versatile Disc - Read-Only Memory (DVD-ROM) discs can hold around 4.7GB of data (a dual-layer DVD can hold twice that). DVD-ROMs are random-access devices. DVD-ROMs are used in the same way as CD-ROMs (see above) but, since they can hold more data, they are also used to store high-quality video. Blu-Ray Blu-Ray disks are a recent replacement for DVDs. A Blu-Ray disc can hold 25 - 50GB of data (a dual-layer Blu-Ray disc can hold twice that). Blu-Ray discs are random-access devices. Blu-Ray discs are used in the same way as DVD-ROMs but, since they can hold more data, they are also used to store very high-quality, high-definition (HD) video. Recordable Optical Discs Recordable optical discs can have data written onto them (‘burnt’) by a computer user using a special disc drive (a disc ‘burner’). CD-Recordable (CD-R) and DVD-recordable (DVD-R) discs can have data burnt onto them, but not erased.You can keep adding data until the disc is full, but you cannot remove any data or re-use a full disc. CD-ReWritable (CD-RW) and DVD-ReWritable (DVDRW) discs, unlike CD-Rs and DVD-Rs, can have data burnt onto them and also erased so that the discs can be re-used. Solid-State Storage Devices '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... USB Memory Sticks Memory sticks are non-volatile, random-access storage devices. Each of these small devices has some flash memory connected to a USB interface. Plug it into your computer and it appears as a drive.You can then add files, erase files, etc.You can use it to move any type of file between computers. Flash memory used to be very expensive, but in recent years it has become much cheaper and you can now buy a 16GB memory stick for just a few dollars. Memory Cards Many of our digital devices (cameras, mobile phones, MP3 players, etc.) require compact, non-volatile data storage. Flash memory cards provide this and come in a variety of shapes and sizes. One of the most common formats used by digital cameras is the SD Card. The cards store the digital images taken by the camera. Mobile phones contain a Subscriber Identity Module (SIM) card that contains the phone’s number, the phonebook numbers, text messages, etc. Many phones also have extra memory cards to store music, video, photos, etc. Backing Up Data What is a Backup? A backup simply means making one or more copies of your data. For example, if you have a folder of photos stored on the hard-drive of your laptop, you might back them up by copying them to a CD-R. Why Backup Your Data? If you delete a file by accident or your computer breaks or your laptop is stolen, or your business burns to the ground, having a backup copy means that you have not lost your precious data. You can recover your lost files and continue working.