Computer Components: PDF

—Control unit and arithmetic logic unit (ALU) :the two main parts The control unit is responsible for obtaining and executing instructions...

—Control unit and arithmetic logic unit (ALU) :the two main parts The control unit is responsible for obtaining and executing instructions from the computer’s.memory The ALU performs the arithmetic and logic functions for the computer. The ALU handles ,addition, subtraction, multiplication, and division and also makes logical and comparison decisions. One indicator of a CPU’s processing power is its clock speed. Clock speed measures the speed at which a CPU processes data (number of instructions per second) and is measured in hertz (Hz)—these days, usually gigahertz (GHz). Early computers had CPUs that processed at speeds of less than 5 megahertz (MHz), whereas modern processors can operate at over 3 GHz (the equivalent of 3,000 MHz) and newer processors continue to surpass these numbers. Nonvolatile memory includes Read-Only Memory (ROM), which is.prerecorded on a chip Temporary memory, the computer’s volatile memory, is Random Access Memory (RAM). Memory is another critical computer component of a computer system. The term memorysignifies storage. There are two basic types of memory: temporary, or ,volatile, and nonvolatile. Nonvolatile memory includes Read-Only Memory (ROM) ,which is prerecorded on a chip. The information on a ROM chip cannot be changed removed, or rewritten, and is generally inaccessible to the computer user. ROM is.nonvolatile memory because it retains its contents even if the computer is turned off ROM contains critical information, such as the program used to start up or boot the ,computer. Storage devices, such as hard disks and flash drives, and storage media such as CDs and DVDs, are considered nonvolatile memory. These are presented later in this chapter. Temporary memory, the computer’s volatile memory, is Random.Access Memory (RAM) Random Access Memory (RAM) acts as the computer’s short-term memory and stores data and program instructions waiting to be processed. RAM is considered volatile  because it’s always in flux, constantly changing, and its contents are erased when the computer is turned off. Installing additional memory is one of the most inexpensive and easiest upgrades for your computer and often results in noticeable performance improvements. It is, in fact, the combination of the processor’s speed and amount of RAM that gives your computer its overall quickness of performance. Output devices display information after data has been processed in a.useful format Monitors and printers are the most.common output devices Resolution, dot pitch, and refresh rate determine a monitor’s display.quality Touchscreen monitors are both input and output devices. Monitors are display devices that show images of text, graphics, and video once data has been processed. The image on a monitor is called soft copy—you can view it, but.you cannot touch it; it is intangible A monitor’s display is made up of millions of tiny dots known as pixels or picture elements. Each pixel represents a single point on a display screen or in a graphic image. The number of pixels on the screen determines a monitor’s sharpness and clarity, also known as its resolution. A higher number of pixels results in a clearer.and sharper monitor resolution and smaller image size Dot pitch refers to the diagonal distance between two pixels of the same color. Dot pitch is measured in millimeters, with smaller measurements resulting in a crisper viewing image because there is less blank space between the pixels. LCD monitors.use an electric current to illuminate the pixels Refresh rate is the speed at which the pixels are reilluminated and it’s measured in cycles per second, expressed as hertz (Hz). Higher refresh rates result in less screen.flicker and less eye strain Touchscreen monitors are both input and output devices. They display images only  like regular monitors, but also enable users to touch their surfaces and make selections directly from the screen. Impact printers (dot matrix) have small hammers, that strike an ink ribbon against paper Nonimpact printers (inkjet, laser) do not touch the paper when printing All-in-one printers bundle multiple capabilities (print, copy, fax, scan) in one device. An impact printer has small hammers, similar to a typewriter’s, that strike an ink ribbon against paper, leaving behind the image of the character or symbol. The dot matrix printer is an impact printer. Its usage today is limited to certain applications ,that require continuous forms or multipart forms (an original and several copies).such as invoices or purchase orders Nonimpact printers do not actually touch the paper when printing. The two most.commonly used with home computers are the ink-jet printer and the laser printer The ink-jet printer uses a special nozzle and ink cartridges to spray ink in small droplets onto the surface of the paper. Laser printers use a special cylinder known as a drum, dry ink or toner, and a laser. Static electricity attracts toner to the surface of the drum, and the laser distributes the toner in the correct pattern. The drum transfers the toner to the paper and heat is used to permanently fuse the toner to.the paper When you select a printer, there are some key characteristics to consider. Print speed is often expressed as pages per minute (ppm). Print speed can vary depending on the manufacturer and model, and is also affected by whether the page is text-only, if it includes graphics, and if the printout is in color, black, or grayscale. Just as with. monitors, resolution is also important to print quality. For printing purposes, resolution is expressed as dots per inch (dpi). The higher the dpi, the better the print quality will.be. Color output and its related cost is another important consideration An all-in-one printer, a type of multifunction device (MFD), bundles multiple capabilities (printing, scanning, copying, and faxing) in one device. Speakers and multimedia projectors are also examples of output devices. Many  computers include small speakers to enable the user to listen to CDs or DVDs and hear any auditory signals the computer sends. Multimedia projectors are used to conduct.presentations and training sessions A digital camera is a device that stores pictures digitally rather than by using conventional film. After images are captured, they are stored in the camera’s internal memory. Some cameras use removable flash memory cards as storage media. These ,cards can be read by a computer, which can then edit them and save them as files. So ,the camera itself is a form of handheld computer, which if connected to a computer serves as an input/output device (I/O). The same thing can be said to describe camcorders. Used to store data, information, and programs for future use Nonvolatile memory—data saved to a storage device remains there until the user deletes or overwrites it Data can be stored on internal hardware devices or in removable units that enable portability. Used to store data, information, and programs for future use Nonvolatile memory—data saved to a storage device remains there until the user deletes or overwrites it Data can be stored on internal hardware devices or in removable units that enable portability. Magnetic storage uses tape or film covered in a thin, magnetic coating that enables data to be saved as magnetic impulses. It works in much the same fashion as an audiocassette or videotape works. Hard drives and backup tape drives are both forms of magnetic storage. Before magnetic storage can occur, media has to be.formatted. This is the process in which media is divided into tracks and sectors.Tracks are magnetic concentric circles and sectors are segments within those circles.Data is stored magnetically within the spaces created by these tracks and sectors  Magnetic media has read/write capability, which means it is possible to use it over.and over again, enabling you to delete or revise existing data and save new data Optical storage uses flat plastic discs coated in a special reflective material. Data is saved by using a laser beam to burn tiny pits into the storage medium. A less intensive laser is used to read the saved data. CDs (compact discs) and DVDs (digital.video discs) are examples of optical media Solid-State Storage (SSD) uses solid-state technology. It is completely electronic and has no moving mechanical parts. Also called flash memory, it is a quick and easy form of rewritable storage and is often used in mobile devices such as digital cameras and MP3 players. Depending on the manufacturer, flash memory cards may be.called Memory Stick, CompactFlash, Secure Digital, or Multi Media Card Flash drives are removable storage devices that use flash memory and connect to the computer by a USB port. The flash drive is typically a device small enough to fit on a keychain or in a pocket, and because of its solid-state circuitry and lack of.moving parts, it is extremely durable