CS chapter 2

major functions of computer*

1. Input: It gathers data, or allows users to enter data. 2. Process: It manipulates, calculates, or organizes that data into information. 3. Output: It displays data and information in a form suitable for the user. 4. Storage: It saves data and information for later use.

portable computers

A laptop computer (or notebook computer) is a portable . A netbook is a small, lightweight laptop computer with a longer battery life than a laptop. A tablet PC is similar to a laptop, but the monitor swivels and folds flat. A tablet computer, such as the iPad or Samsung Galaxy Tab, is a portable computer integrated into a flat multitouch-sensitive screen. An ultrabook is a full-featured but lightweight laptop computer designed to compete with the MacBook Air. A desktop computer is intended for use at a single location, so it is stationary. Most desktop computers consist of a separate case or tower that houses the main components of the computer plus peripheral devices. An all-in-one computer, such as the Apple iMac or HP TouchSmart, eliminates the need for a separate tower because these computers house the computer's processor and memory in the monitor.

image input

Digital cameras, camcorders, and cell phones are common devices for capturing pictures and video, and all of them are considered input devices. Scanners can also input images. create a digital image, which you can print, scan, or e-mail. A webcam is able to capture still images, they're used mostly for capturing and transmitting live video. Videoconferencing technology lets a person using a computer equipped with a webcam and a microphone transmit video and audio across the Internet.

selecting a printer

Inkjet or color laser for photos and graphics at higher cost. B&w laser printer for text documents for speed a printer or a device that prints and scans, copies, or faxes (an all-in-one). In addition, you should decide whether you want to print wirelessly. Speed: pages per minute (PPM). Laser printers often print faster than inkjets. Resolution: image clarity. dots per inch (dpi). Recommended dpi for black-and-white text is 300, general-purpose imager is 1200, photos is 4800. Color output: Inkjet and laser color have four colors (black, cyan, magenta, yellow). Higher quality six cartridges (plus light cyan and light magenta). With separate cartridges, you only need to replace the empty one. Cost of consumables.

Byte*

Kilobytes, megabytes, and gigabytes are therefore simply larger bytes. As shown in this table, a kilobyte (KB) is approximately 1,000 bytes, a megabyte (MB) is about 1 million bytes, and a gigabyte (GB) is around 1 billion bytes. Many business computers can store up to a petabyte of data.

lcd monitors

Monitor screens are grids made up of millions of tiny dots called pixels. Each pixel is actually made up of three red, blue, and green subpixels; some newer LCD TVs on the market have even added a fourth color: yellow. LCD monitors are made of two or more sheets of material filled with a liquid crystal solution. A fluorescent panel at the back of the LCD monitor generates light waves. When electric current passes through the liquid crystal solution, the crystals move around and either block the fluorescent light or let the light shine through. This blocking or passing of light by the crystals causes images to form on the screen. The aspect ratio is the width to height proportion of a monitor. Traditionally, aspect ratios have been 4:3, an aspect ratio of 16:9 to accommodate HD format video. The screen resolution, or the clearness or sharpness of the image, reflects the number of pixels on the screen. An LCD monitor might have a native (or maximum) resolution of 1600 x 1200, meaning it contains 1,600 vertical columns with 1,200 pixels in each column. the resolution of an LCD monitor is dictated by the screen size and aspect ratio. The contrast ratio is the measure in the difference in light intensity between the brightest white and the darkest black that the monitor can produce. A contrast ratio between 400:1 and 1,000:1 is preferable. The viewing angle measures how far you can move to the side of (or above or below) the monitor before the image quality degrades to unacceptable levels. For monitors that measure 17 inches or more, a viewing angle of at least 150 degrees is usually recommended. Brightness is a measure of the greatest amount of light showing when the monitor is displaying pure white. A brightness level of 300 cd/m2 or greater is recommended. Response time is the time it takes for a pixel to change color. A lower response time means faster transitions; therefore moving images will appear less jerky.

optical storage

Most desktop and laptop computers include at least one optical drive that can read from and maybe even write to CDs, DVDs, or Blu-ray discs. Data is saved to such discs as tiny pits that are burned into the disc by a high-speed laser. Compact discs (CDs) were initially created to store audio files. Digital video (or versatile) discs (DVDs) hold up to 14 times more data than CDs. Blu-ray can hold as much as 50 GB of data—enough to hold approximately 4.5 hours of movies in the high-definition (HD) digital format. Many systems are now available with BD-ROM drives and even Blu-ray burner

Drive bay

Permanent storage devices are Internal drive bays. They cannot be seen or accessed from outside the system unit. Generally, internal drive bays are reserved for internal hard drives. External drive bays can be seen and accessed from outside the system unit. External drive bays house CD and DVD drives, for example. On desktop computers, sometimes there are empty external drive bays that can be used to install additional drives. These extra spaces are covered by a faceplate on the front panel. Laptop expansion is done by attaching an external drive to the computer through a USB port.

hertz (Hz)

Processor speed is measured in units of ...is a measurement of machine cycles per second. CPU performance is also affected by the number of cores, or processing paths, the processor has. Processors have been designed that have two, four, and even eight cores.

power controls

The power supply, which is housed inside the system unit, transforms the wall voltage to the voltages required by computer chips. Powering on from turned-off state, is called a cold boot. power-management settings that allow the most power-hungry components of the system (the hard drive and monitor) to shut down after a short idle period. In Sleep Mode, all of the documents, applications, and data you were using remain in RAM (memory), where they're quickly accessible when you restart your computer. Hibernate option is similar; your data is stored on your hard drive instead of in RAM and your computer is powered off. This uses much less battery power than Sleep and is a good choice if you won't be using your laptop for a long time and won't have the opportunity to charge it. Restarting the system while it's powered on is called a warm boot. You might need to perform a warm boot if the operating system or other software application stops responding

binary language*

computer language. consists of just two digits: 0 and 1. Everything a computer does, such as processing data, printing a report, or editing a photo, is broken down into a series of 0s and 1s. Each 0 and 1 is a binary digit, or bit for short. Eight binary digits (or bits) combine to create 1 byte. In computers, each letter of the alphabet, each number, and each special character (such as the @ sign) consists of a unique combination of 8 bits, or a string of eight 0s and 1s.

touch screens

display screen that responds to commands initiated by a touch with a finger or a stylus. Touch screens are becoming the norm on many computing devices, especially smartphones such as the Droid and iPhone, and tablet computers such as the iPad and Samsung Galaxy Tab. Tablets and other touch-screen devices use a virtual keyboard that displays on screen when text input is required. These keyboards show basic keyboard configurations, and use special keys to switch to numeric, punctuation, and other keys.

input device*

enables you to enter data (text, images, and sounds) and instructions (user responses and commands) into your computer. A keyboard is an input device you use to enter typed data and commands, and a mouse is used to enter user responses and commands. There are other input devices as well. Microphones input sounds, scanners and digital cameras input nondigital text and digital images, respectively. A stylus is an input device that looks like a skinny pen, which you use to tap commands or draw on a screen.

qwerty layout

gets its name from the first six letters in the top-left row of alphabetic keys on the keyboard and is the standard English-language keyboard layout. To save space and weight, netbook and smaller laptop keyboards (14" and under) are more compact than standard desktop keyboards, and therefore often have fewer keys. Wireless keyboards send data using radio frequency (RF). Flexible keyboards are a terrific alternative if you want a full-sized keyboard for your laptop, netbook, or tablet. The virtual laser keyboard is another compact keyboard alternative and is about the size of cell phone. It projects an image of a keyboard onto any flat surface, and sensors detect the motion of your fingers as you "type."

smartphone

has productivity (application software), media player, and camera features, as well as Web connectivity. A smartphone has a CPU, memory, and storage just like a laptop computer.

ROM (read-only-memory)*

holds all the instructions the computer needs to start up when it is powered on. The instructions stored in ROM are permanent, making ROM a nonvolatile storage location, which means the data isn't erased when the power is turned off.

printers

inkjet and laser, are nonimpact printer sprays ink or uses laser beams to transfer marks onto the paper. An impact printer has tiny hammer-like keys that strike the paper through an inked ribbon, making marks on the paper. For most users, impact printers are legacy technology. Inkjet printers are affordable and produce high-quality color printouts quickly and quietly. work by spraying tiny drops of ink onto paper and are great for printing black-and-white text as well as color images. Laser printers use laser beams and static electricity to deliver toner (similar to ink) onto the correct areas of the page. Heat is used to fuse the toner to the page, making the image permanent. They have a faster printing speed than inkjet printers and produce higher quality printouts. There are two types of wireless printers: WiFi and Bluetooth. Both WiFi and Bluetooth printers have a range of up to approximately 300 feet. WiFi sends data more quickly than Bluetooth. AirPrint is a feature of iOS that facilitates printing to AirPrint-compatible wireless printers. A plotter prints oversize pictures that require the drawing of precise and continuous lines, such as maps and architectural plans. Plotters use a computer-controlled pen that provides a greater level of precision than the series of dots that laser or inkjet printers make. A thermal printer works by either by melting wax-based ink onto ordinary paper (a process called thermal wax transfer printing) or by burning dots onto specially coated paper (a process called direct thermal printing). They are used in stores to print receipts and in airports for electronic ticketing and many models feature wireless technology. Thermal printers are also popular for mobile printing in conjunction with smartphones and similar devices.

mainframe

is a large, expensive computer that supports many users simultaneously. Mainframes are often used in businesses that manage large amounts of data, such as insurance companies, where many people are working at the same time on similar operations, like claims processing. Mainframes excel at executing many different computer programs at the same time.

port

is a place through which a peripheral device attaches to the computer so that data can be exchanged between it and the operating system.

data

is a representation of a fact, figure, or idea. Can be a number, a word, a picture, or even a recording of sound. For example, the number 7135553297 and the names Zoe and Richardson are pieces of this.

embedded computer

is a specially designed computer chip that resides in another device, such as your car or the electronic thermostat in your home. Embedded computers are self-contained computer devices that have their own programming that typically don't receive input from you or interact with other systems.

supercomputer

is a specially designed computer that can perform complex calculations extremely rapidly. Supercomputers are used when complex models requiring intensive mathematical calculations are needed (such as weather forecasting or atomic energy research). Supercomputers are designed to execute a few programs as quickly as possible, whereas mainframes are designed to handle many programs running at the same time but at a slower pace.

Information

is data that has been organized or presented in a meaningful fashion. When your computer provides you with a contact listing that indicates Zoe Richardson can be reached by phone at (713) 555-3297, the data mentioned earlier suddenly becomes useful—that is, it becomes this.

CPU

is sometimes referred to as the "brains" of the computer because it controls all the functions performed by the computer's other components and processes all the commands issued to it by software instructions. Modern CPUs can perform as many as tens of billions of tasks per second without error, making them extremely powerful components.

motherboard

is the main circuit board that contains the central electronic components of the computer, including the computer's processor (CPU), its memory, and the many circuit boards that help the computer function. On a desktop, the motherboard is located inside the system unit, the metal or plastic case that also houses the power source and all the storage devices (CD/DVD drive and hard drive). In a laptop computer, the system unit is combined with the monitor and the keyboard into a single package. The motherboard also includes slots for expansion cards (or adapter cards), which are circuit boards that provide additional functionality. Typical expansion cards found in the system unit are sound and video cards. A sound card provides a connection for the speakers and microphone, whereas a video card provides a connection for the monitor. Laptops have video and sound capabilities integrated into their motherboards. A network interface card (NIC), which enables your computer to connect with other computers or to a cable modem to facilitate a high-speed Internet connection, is now the most common connectivity port.

RAM (random access memory)*

is the place in a computer where the programs and data the computer is currently using are stored. RAM is much faster to read from and write to than the hard drive and other forms of storage. Because the entire contents of RAM are erased when you turn off the computer, RAM is the temporary or volatile storage location. To save data more permanently, you need to save it to the hard drive or to another permanent storage device such as a CD or flash drive.

universal serial bus (USB) port

is the port type most commonly used to connect input and output devices to the computer. USB 2.0 ports are the current standard and transfer data at 480 megabits per second (Mbps). The new USB 3.0 standard provides transfer speeds of 4.8 Gbps and charges devices faster than its predecessor. A connectivity port can give you access to networks and the Internet. To find a connectivity port, look for a port that resembles a standard phone jack but is slightly larger. This port is called an Ethernet port. Ethernet ports transfer data at speeds up to 10,000 Mbps. You can use an Ethernet port to connect your computer to a digital subscriber line (DSL) or cable modem, or a network. Modem port is a second connectivity port that will accept a standard phone line connector. It uses a traditional telephone signal to connect to the Internet over a phone line. Audio ports connect headphones, microphones, and speakers. A video port is needed to attach a monitor to a desktop computer or a second, larger display to a laptop computer. The video graphics array (VGA) port is the port to which older LCD monitors connect. Newer LCD monitors, as well as other multimedia devices such as televisions, DVD players, and projectors, connect to digital video interface (DVI) ports. The latest digital connector designed for use in HD home theater environments is a high-definition multimedia interface (HDMI), a compact audio-video interface that carries both HD video and uncompressed digital audio on one cable.

software*

is the set of computer programs that enables the hardware to perform different tasks. There are two broad categories of software: application software and system software.

system software

is the set of programs that enables your computer's hardware devices and application software to work together. The most common type of system software is the operating system (OS)—the program that controls how your computer system functions. It manages the hardware, such as the monitor and the printer, and provides a means by which users can interact with the computer.

application software

is the set of programs you use on a computer to help you carry out tasks such as writing a research paper. If you've ever typed a document, created a spreadsheet, or edited a digital photo, for example, then you've used application software.

Hard disk drive (HDD)

is your computer's primary device for permanent storage of software and documents...is a nonvolatile storage device. An internal hard drive resides within the system unit and usually holds all permanently stored programs and data. The most common type of hard drive has moveable parts - spinning platters, a moving arm with a read/write head - that can fail and lead to devastating disk failure solid-state drive (SSD) have no moving parts so they're more efficient, run with no noise, emit little heat, and require little power. They're less likely to fail after being bumped or dropped.

game controllers

joysticks, game pads, and steering wheels are also considered input devices because they send data to the computer. They have buttons and miniature pointing devices that provide input to the computer. Most game controllers, such as those for Rock Band and the Wii system, are wireless to provide extra mobility.

output device

lets you send processed data out of your computer in the form of text, pictures (graphics), sounds (audio), or video. The most common output device is a monitor, which displays text, graphics, and video as soft copies (copies you can see only on screen). Another common output device is a printer, which creates hard copies (copies you can touch) of text and graphics. Speakers and earphones (or earbuds) are the output devices for sound. The most common type of monitor is a liquid crystal display (LCD), also called a flat-panel monitor, which is light and energy efficient. Some newer monitors use light-emitting diode (LED) technology, which is even more energy efficient, and might have better color accuracy and thinner panels than LCD monitors. CRT monitors are difficult to find or buy because they have become legacy technology. Organic light-emitting diode (OLED) displays use organic compounds that produce light when exposed to an electric current. Unlike LCDs and LEDs, OLEDs do not require a backlight to function and therefore draw less power and have a much thinner display, sometimes as thin as 3 mm. They are also brighter and more environmentally friendly than LCDs. Because of their lower power needs, OLED displays run longer on a single battery charge and is used in your cell phone, iPod, and digital camera.

mice

optical mouse uses an internal sensor or laser to detect the mouse's movement. The sensor sends signals to the computer, telling it where to move the pointer on the screen. Optical mice don't require a mouse pad, although you can use one to enhance the movement of the mouse on an uneven surface, or to protect your work surface from being scratched. Wireless mice are similar to wireless keyboards in that they use batteries and send data to the computer by radio frequency or Bluetooth technologies. Apple has developed Magic Mouse, the first multitouch wireless mouse. The top surface of the mouse is the button. Use your finger to scroll in any direction, swipe your fingers across the mouse to move through web pages and photos, and tap on the mouse to click and double-click.

sound output

speakers, headphones, which are the output devices for sound. a more sophisticated speaker system, such as one that includes subwoofers (special speakers that produce only low bass sounds) and surround-sound speakers. A surround-sound speaker is a system of speakers and audio processing that envelops the listener in a 360-degree field of sound

integrated pointing device

touch pad (or trackpad), a small, touch-sensitive area at the base of the keyboard. Some laptops incorporate a trackpoint device, a small, joystick-like nub that allows you to move the cursor with the tip of your finger.

sound input

using a microphone (mic), a device that lets you capture sound waves (such as your voice) and transfer them to digital format on your computer. Omnidirectional microphones pick up sounds from all directions at once. These mics are best for recording more than one voice, such as during a conference call when you need to pick up the voices of multiple speakers. Unidirectional microphones pick up sound from only one direction. These are best used for recording podcasts with a single voice or making phone calls over the Internet with only one person on the sender's end of the call. Clip-on microphones (also called lavalier microphones) are wireless