2Understanding Computer Understanding Input Devices Table of ContentsUnderstanding ComputerUnderstanding Input DevicesUnderstanding Output DevicesUnderstanding How Data is Processed and StoredComputer SoftwareStorage DevicesComputer Safety
3ComputerA computer is an electronic machine that takes in data, stores and processes the data, and then produces information. Computers work because they are controlled by instructions stored in memory. They process the data according to these instructions.
4softwareComputerHardwaredataWhen people talk about computers, they refer to hardware and software. The parts of the computer you can see and touch are called hardware. The instructions are called computer programs or software. Data is the raw facts in the form of words, sounds, numbers, or pictures.
5ComputerInformationMemoryInputInput is the data you enter into a computer. A computer uses memory and storage to store data. A computer processes data to produce information. Information is data that has been processed so that it is organized, useful, and meaningful. Output is what the computer produces. Output can be words, sounds, numbers, or pictures.
6ComputerComputers are divided into three general categories: supercomputers, mainframes, and personal computers.
7ComputerSupercomputer are the fastest, most powerful, most expensive, and largest computers. Supercomputers are used by governments, scientists, and businesses, when complicated jobs need to be done.
8ComputerMainframe computers also are large computers that do large jobs. The amount of data processed and the speed at which the data is processed is not as great as for supercomputers. A hospital might use a mainframe computer to schedule the staff, keep track of the patients, and make sure people get the right medications.
9ComputerPersonal computers are computers that people use in their daily lives. Personal computers are smaller and process less data at slower speeds that mainframe computers.
10ComputerThe two main types of personal computers are PC compatibles (PC’s) and Macintosh computers (Macs) made by Apple computer company. The two biggest differences between Apple computers and PCs are the operating systems and the basic processor.
11ComputerA notebook computer, also called laptop, is a personal computer that is small enough to fit in a backpack.A handheld computer, also called PDA, is an even smaller personal compute that you can hold in your hand.
12Understanding Input Devices Each piece of hardware is called a device. Different devices have different jobs. You use an input device to enter data into the computer. The keyboard and the mouse are input devices. The microphone, camera, and scanner also are input devices
13Input DeviceFunction keysNumeric keypadStandard keyboardYou use the keyboard to type characters into the computer. Characters are letters, numbers, and symbols. A typical keyboard has between 101 and 105 keys. The three areas of the keyboard are the standard typing area, numeric keypad, and function keys.
14Input DeviceThe mouse is a pointing device that is designed to fit in the palm of your hand. You press and release the mouse button to input data. The press and release is called a click. You drag, point, click, and double-click the mouse to give commands to the computer.
15Input DeviceA scanner, a digital camera, a touch screen, a digital video camera, a graphic tablet, and a microphone are examples of other input devices. The input device depends on the data you have to enter.
16Understanding Output Devices You use an output device to get information out of the computer. A printer prints the information on paper. Speakers or headphones play sound as the output. The monitor, speakers, and printer are the output devices you will use the most.
17Output DeviceA monitor shows you information on a screen like a television set. When you turn on a computer, you will see icons, pictures, and words on the screen. The screen you see when you start the computer is called the desktop.
18Output DeviceA printer prints the information on paper. Your computer is connected to a printer. You print when you need the output on paper. One printer might be connected through a network to many computers. Computers that are on a network can share one printer.
19Output DevicePrinters are categorized in several ways, including the technology they use to print, the number of pages they can print in a minute, and whether they can print using colored inks.
20Output DeviceThe fastest, but most expensive printers, are called laser printers. Laser printers use a beam of light to transfer toner onto paper to create the images. Toner is a fine powder that works like ink. Printing speeds are measured as ppm, which stands for pages per minute. Laser printers can print at speeds of up to 40 ppm.
21Output DeviceInk-jet printers, although slower than laser printers, print at speeds of one to eight pages per minute. In-jet printers use a special nozzle to spray small drops of colored ink on paper to create the image.
22Output DeviceSound CardSpeakers are an output device for words, music or sounds. Computers have two or more speakers because of the way sound is distributed. A sound card is hardware inside the system unit that processes the sounds. Headphones rest on your head and cover your ears so that only you hear the sounds.
23How Data is Processed and Stored UnderstandingHow Data Is Processedand StoredThe system unit has hardware inside that processes the data. The system unit is closed to protect the processing hardware.
24How Data is Processed and Stored If you opened the computer, you would see chips. A chip is a small, electronic device. A chip is manufactured from a silicon wafer, which is cut to a small size and imprinted with circuits and electronic devices.
25How Data is Processed and Stored The motherboard is the main circuit board in the system unit. It also is called the system board. All the chips and other electronic components of the system unit are connected to the motherboard.
26How Data is Processed and Stored The Processor is one type of chip. The brains of every computer is the processor. The processor also is called the CPU. CPU stands for Central Processing Unit – it does all the processing.
27How Data is Processed and Stored Computers also have memory chips. Some memory chips in computer are called RAM. RAM, which stands for random access memory, temporarily stores data and programs while you work on the computer.
28How Data is Processed and Stored Digital computers use special codes to understand data. Digital uses 0’s and 1’s to represent a choice of one of two states – on or off, yes or no, one or zero.
29How Data is Processed and Stored 8 bits equals 1 byteEach 0 or 1 is called a bit; these bits are organized into groups of eight, which are called bytes. A byte represents one character.
30How Data is Processed and Stored Kilobyte means one thousand bytes 1,000Megabyte means one million bytes 1,000,000Gigabyte means one billion bytes 1,000,000,000Memory is measured in kilobytes or megabytes. Storage, where data and programs are kept after the computer is turned off, is measured in gigabytes.
31How Data is Processed and Stored Input devices are connected to the computer by using cables that plug into ports. A port is what you plug the connector into so data can be transmitted to the computer. Circuit boards that connect to the motherboard have ports that are visible on the back of the system unit. Different types of port connects peripherals.
32How Data is Processed and Stored A USB port connects devices such as digital cameras.
33How Data is Processed and Stored A serial port connects devices such as a joystick or modem.
34How Data is Processed and Stored A parallel port connects printers.
35Computer Software Computer Software Hardware and Software work together in a computer to process data and create information. You have learned that software, or a program, contains the instructions that tell the computer what to do. The two main types of software are system software and application software.
36Computer SoftwareSystem software is the operating system. The operating system runs the computer. It is like the boss of all the software in the computer.
37Computer SoftwareIf you have a PC, you probably have a version of the Windows operating system running your computer.If you have a Mac computer, you have a version of the Mac OS running your computer.
38Computer SoftwareApplication software is a program that does a specific job. You can install different applications depending on the jobs you want the computer to do. Many different types of software are available.
39Storage Devices Storage Devices Computers use files to store data. Files can have instructions, words, pictures, sounds or numbers. Software is stored in files. Each file has a file name that identifies the file. Storage devices read the data from the storage media and write data to the storage media.
40Storage DevicesA floppy disk is removable storage; you can take it with you. Floppy disks are magnetic media, which means they use magnetic technology to create patterns of 0s and 1s to store data.
41Storage DevicesA hard disk is a storage device that is inside the system unit of your computer. The hard disk also uses magnetic technology to record the data.
42Storage DevicesA CD is a compact disc. CDs use optical technology to create the pattern of 0s and 1s to store data. Optical technology is laser, or light, technology. A CD-ROM stores software. It also can store music files and data files. ROM stands for Read Only Memory.
43Storage DevicesA CD-ROM drive is the hardware a computer uses to read data, music and software form a CD. A CD-R can read from a CD and also can write data, music, and software on a CD-R.
44Storage DevicesDVD-ROM (digital video disc-ROM) is another type of optical storage technology. DVDs can store much more data than CDs. DVD-ROMs are used to store large software programs or full-length films.
45Computer Safety Computer Safety Ethics are rules to help you know whether something is right or wrong. Etiquette is how you behave. Netiquette is etiquette on the Internet. You will learn about rules that you must follow when you are on the Internet.
46Protecting the Computer Computer SafetyProtecting the ComputerComputers are expensive; you must treat a computer as you would any valuable machine. You cannot eat or drink while you work on a computer. Be sure your hands are clean before you type on a keyboard. Hold floppy disk, CD-ROM, and DVD-ROMs properly. If you have a problem with a computer, ask your teacher or the person in charge for help. Do not put heavy objects on the computer. Do not bang or hit the hardware.
47Computer SafetySometimes programs contain errors that cause the computer to do things that you do not expect. A crash is when the computer stops working, and you have to restart the computer. These errors or mistakes in programming are called bugs.
48Computer SafetyA computer virus is a program design by a person on purpose to harm other peoples’ computers. A computer virus can cause your computer to crash in such a way that you cannot restart it easily.
49Computer SafetyYou can protect your computer from viruses by using antivirus software. You install antivirus software on your computer to detect and remove viruses before they can do harm.
50Computer SafetyMake sure an adult knows when you are working on a computer. If you see something on the screen that scares you or makes you sad, quit the program and then tell your teacher.
51Computer SafetyYou always should be considerate of others’ work. You should get permission to use things that are not yours. You never should comply somebody’s work or software without asking for permission. A copyright means the person who created the work also owns the work.
52Computer SafetyAny information about you, your family, and your friends is personal. Do not give out names, addresses, or telephone numbers to anyone unless you have permission from them, a family member, or a teacher. You know which files are yours because you named them. Never open other people’s files unless you get permission. You should never delete any files that you did not create.