Computer Competency Study Guide
Mouse
A small handheld device that controls the movement of a symbol on the screen called a pointer. With it, you can make choices, initiate a process and select objects.
Universal serial bus (USB) port
Can connect up to 127 different peripheral devices with a single connector type.
A "head crash"
Can occur when a read/write head becomes misaligned, if the disk wobbles, or if the head runs into a stray bit of dust.
Speakers
Allow the user to hear music, voice, and other sounds generated by the computer.
Microphone
Allows a user to speak to the computer to enter data and instructions into the computer.
Digital camera
Allows a user to take pictures and transfer the photographed image to the computer, instead of storing on traditional film.
PC camera
Allows the users to have video telephone or conference calls - where the participants can see each other while communicating.
Input Devices
Any hardware component that allows a user to enter data or instructions into a computer. Six commonly used are the keyboard, mouse, microphone, scanner, digital camera and PC camera.
Output Devices
Any hardware component that can convey information to a user. Three commonly used are a printer, a monitor and speakers.
Storage devices, also called auxiliary storage devices or secondary storage devices
Are used to store instructions and data when they are not being used in memory. Four common types of auxiliary storage are floppy disks, hard disks, compact disks and zip disks.
Memory, also called random access memory, or RAM
Consists of electronic components that store data including numbers, letters of the alphabet, graphics, and sound. Most RAM is volatile, meaning it loses its contents when the power is removed from the computer. Any data to be processed must be stored in memory. The amount of memory is typically measured in kilobytes or megabytes. One kilobyte (K or KB) equals approximately 1,000 memory locations and one megabyte (M or MB) equals approximately one million memory locations. A memory location, or byte, usually stores one character. Therefore, a computer with 512 MB of memory can store approximately 512 million characters.
Hard disk
Consists of one or more rigid metal platters that allow data to be recorded magnetically on the surface of the platters. Although some hard disks are available in a portable cartridge form, most are not removable.Like floppy disks the data is recorded on a series of tracks and the tracks are divided into sectors when the disk is formatted.Storage capacities of internally mounted hard disks for PCs range from one billion characters to more than seventy-five billion characters. One billion bytes are called a gigabyte (GB). Typical hard disk sizes range from 10 GB to 250 GB or more.
Keyboard
Contains keys that allow a user to enter data and instructions into a computer.
The central processing unit (CPU)
Contains the electronic circuits that cause processing to occur. It is made up of the control unit and the arithmetic/logic unit. The control unit interprets the instructions. The arithmetic/logic unit performs the logical and arithmetic processes. On personal computers, it is designed into a chip called a processor. Manufacturers state clock speed (the speed at which a processor executes instructions) in megahertz (MHz) or gigahertz (GHz).
The five primary components of a computer
Input devices, Output devices, Central Processing Unit or CPU, Memory, and Storage devices.
Network
Is a collection of computers and devices connected via communications media and devices such as cables, telephone lines, modems or other means. A network that connects computers in a limited geographic area is called a local area network (LAN). A network that covers a large geographical area is called a wide area network (WAN).
A compact disk (CD)
Is a flat, round, portable, metal storage medium. Compact discs are available in a variety of forms including CD-ROMs, CD-Rs, and CD-RWs,. DVDs (DVD-ROMs, DVD-Rs, DVD+Rs, DVD-RWs etc) are similar in form, but hold far more data. A CD-ROM, or compact disc read-only memory, is a compact disc that uses the same laser technology as audio CDs for recording music. In addition to audio, a CD-ROM can contain text, graphics, and video. You can only read the contents of these discs; you cannot erase or modify the contents.A typical CD-ROM holds about 650 MB of data. This is about 450 times more than can be stored on a floppy disk.
Zip disk
Is a higher capacity disk that can store the equivalent of up to 170 standard floppy disks. For backup purposes, good choices of media for home users are higher-capacity Zip Disks, CD-Rs, or DVD-Rs.
A CD-R (compact disc-recordable)
Is a multisession compact disc onto which you can record you own data, such as text, graphics, and audio.
A floppy disk, or diskette
Is a portable, inexpensive storage medium that consists of a thin, circular, flexible plastic disk with magnetic coating enclosed in a square-shaped plastic shell. The most widely used is 3.5 inches wide and typically stores up to 1.44 megabytes (1.44MB) of data.It is a type of magnetic disk, which means it uses magnetic patterns to store items on the disks surface. Most floppy disks that you buy are already formatted if not the disk must be formatted before you can write to it. Formatting is the process of preparing a disk (floppy disk or hard disk) for reading and writing by organizing the disk into storage locations called tracks and sectors. A track is a narrow recording band that forms a full circle on the surface of the disk. The disk's storage locations then are divided into pie-shaped sections, which break the tracks into small arcs called sectors. A file that is stored in nonadjacent sectors is referred to as a fragmented file. If you leave a disk in the floppy disk drive, you will see a non-system disk error message when you try to boot the PC.
A CD-RW (compact disc-rewritable)
Is an erasable disc you can write on multiple times. With CD-RWs, the disc acts like a floppy or hard disk allowing you to write and rewrite data onto to it multiple times. Note: CDRW technology allows you to record data on special optical disks - but many standard CD-ROM drives cannot read the data stored on these writable disks.
Shareware
Is copyrighted software that is distributed free for a trial period. A user would have to purchase the use of the shareware beyond the trial period. Application Menu Bars and Controls: Once started, an application displays in a window on the desktop. A window is the rectangular area of the screen that displays a program, data and/or information. The top of the window has a title bar, which is the horizontal space that contains the window's name. The title bar typically contains three control buttons, the Minimize button, the Maximize button and the Close button. A scroll bar on the side of the window helps you move a document or graphic up and down within the window.
Netiquette
Is short for Internet etiquette, is the code of acceptable behaviors users should follow while online.
Freeware
Is software provided at no cost to a user by an individual or company. Freeware is copyrighted and cannot be resold. Public-domain software is also free, but it has been donated for public use and has no copyright restrictions.
Is the transmission of messages and files via a computer network. E-mail server software provides an electronic mailbox for each person, sorts incoming messages into these mailboxes, and routes outgoing mail over the Internet to other E-mail servers.
Monitor
Looks like a small television screen, displays text, graphics, and video information. The viewable size is the diagonal measurement of the actual viewing area.
Printer
Produces text and graphics on a physical medium such as paper or a transparency. This physical format is also referred to as a hard copy. The resolution is measured in DPIs.
Scanner
Reads printed text and pictures and then translates the results into a form the computer can use.
Serial port
The interface that connects devices to the system unit by transmitting data one bit at a time. Mainly used for devices that do not require fast data transmission rates, such as a mouse, keyboard,or modem.
Analog signals
The telephone system uses continuously-variable signals; they work over a continuous range (like the sound that comes from speakers).
Internet
The world's largest network is the Internet. The Internet is a worldwide collection of networks that link businesses, government agencies, educational institutions and individuals. Most users connect to the Internet one of two ways: through an Internet service provider or an Online service provider. An Internet service provider (ISP) is a business that has a permanent Internet connection and provides temporary connections to individuals and companies for free or for a fee. Like an ISP, an Online service provider (OSP) provides Internet access, but also provides a variety of other specialized content and services. A typical Internet connection consists of a computer, a phone line, a modem, and ISP or OSP and communications software. An increasing number of ISPs deliver "broadband" (high-speed) Internet connectivity via digital cable, DSL, or Fiber Optic service. These types of high-speed, always-on Internet connections can be far faster than dialup. One of the most popular segments of the Internet is the World Wide Web (also called the Web), which contains billions of documents called Web pages. A Web site is a related collection of Web pages. You can access and view Web pages using a software program called a Web browser. A Web page has a unique address, called a Uniform Resource Locator (URL). A browser retrieves a Web page by using its URL, or web address. Web page URLs begin with http://. The http stands for HyperText Transfer Protocol, which is the communications standard used to transfer pages to the Web. Web pages are stored and retrieved upon request by Web servers.
DVD-ROMs
To meet the tremendous storage requirements, some software companies have moved from CD-ROMs to the larger DVD-ROM format - a technology that can be used to store large amounts of text and even videos. A DVDROM (digital video disc-ROM) is a very high capacity compact disc capable of storing from 4.7 GB to 17 GB of data. DVDs are also available as Recordable (DVD-R, DVD+R) and Rewritable (DVD-RW, DVD+RW).
Digital signals
Your PC moves and stores data as these signals using a series of 1's and 0's. This data is either on (1) or off(0) at any given time; never any in-between value.
