Учебное пособие состоит из двух частей и англо-русского словаря. Материалом для пособия послужило американское издание для изучающих компьютер P. Norton "Introduction to Computers"
жүктеу/скачать 0,7 Mb.
|
- Бұл бет үшін навигация:
- PC Projectors
- Sound Systems
- Types of Storage Devices
- Magnetic Storage Devices
Monitors and Sound Systems
MonitorsComputer monitors are roughly divided into two categories: CRT and flat-panel displays. Monitors can also be categorized by the number of colors they display. Monitors are usually monochrome, grayscale, or color. A CRT monitor works with one or more electron guns that systematically aim a beam of electrons at every pixel on the screen. Most LCD displays are either active matrix or passive matrix. When purchasing a monitor, you should consider its size, resolution, refresh rate, and dot pitch. The video controller is an interface between the monitor and the CPU. The video controller determines many aspects of a monitor's performance; for example, the video controller lets you select a resolution or set the number of colors to display. The video controller contains its own on-board processor and memory, called video RAM. PC ProjectorsA PC projector is a portable light projector that connects to a PC. This type of projector is rapidly replacing traditional slide projectors and overhead projectors as a means for displaying presentations. Many PC projectors provide the same resolutions and color levels as high-quality monitors, but they project the image on a large screen. The newest PC projectors use digital light processing to project bright, crisp images. A DLP projector uses a special microchip that contains tiny mirrors to produce images. Sound SystemsMultimedia PCs generally come with sound systems, which include a sound card, speakers, a CD-ROM or DVD drive, and a video controller. Printers Printers fall into two general categories: impact and nonimpact. Impact printers create an image on paper by using a device to strike an inked ribbon, pressing ink from the ribbon onto the paper. Nonimpact printers use various methods to place ink (or another colored substance) on the page. When evaluating printers for purchase, you should consider four criteria: image quality, speed, initial cost, and cost of operation. A dot matrix printer is a common type of impact printer. A dot matrix printer uses a print head, which contains a cluster of pins. The printer can push the pins out to form patterns, in rapid sequence. The pins are used to press an inked ribbon against paper, thus creating an image. The lowest resolution dot matrix printers have an array of nine pins; the highest resolution dot matrix printers have twenty-four pins. The speed of dot matrix printers is measured in characters per second. An ink jet printer is an example of a nonimpact printer. It creates an image by spraying tiny droplets of ink onto the paper. Ink jet printers are inexpensive for both color and black printing, have low operating costs, and offer quality and speed comparable to low-end laser printers. Laser printers produce higher-quality print and are fast and convenient to use, but they are also more expensive than ink jet printers. Laser printers are nonimpact printers. They use heat and pressure to bond tiny particles of toner (a dry ink) to paper. Laser printers are available in both color and black and white, and the highest end laser printers provide resolutions of 1200 dpi and greater. Snapshot printers are specialized, small-format printers used to print small color photographs. Snapshot printers are popular among users who own digital cameras. Snapshot printers are fairly slow, and they can be more expensive to operate than standard ink jet or laser printers. Thermal-wax, dye-sublimation, fiery, and IRIS printers are used primarily by print shops and publishers to create high-quality color images. Plotters create large-format images, usually for architectural or engineering purposes, using mechanical drawing arms, ink jet technology, or thermal printing technology. Types of Storage DevicesStorage devices can be categorized as magnetic or optical. The most common magnetic storage devices are diskettes, hard disks, high-capacity floppy disks, disk cartridges, and magnetic tape. The primary types of optical storage are compact disk read-only memory (CD-ROM), digital video disk read-only memory (DVD-ROM), CD-Recordable (CD-R), CD-ReWritable (CD-RW), DVD-Recordable (DVD-R), DVD-ReWritable (DVD-RW) and PhotoCD. Magnetic Storage DevicesMagnetic storage devices work by polarizing tiny pieces of iron on the magnetic medium. Read/write heads contain electromagnets that create magnetic charges on the medium. Diskette drives, also known as floppy disk drives, read and write to diskettes. Diskettes are used most often to transfer files between computers, as a means for distributing software, and as a backup medium. 3.5 inches diskettes are available at present. Before a magnetic disk can be used, it must be formatted – a process that maps the disk's surface and creates tracks and sectors where data can be stored. When a disk is formatted, the operating system creates four distinct areas on its surface: the boot sector, FAT, root folder, and data area. Hard disks can store more data than diskettes because of their higher-quality media, faster rotational speed, and the tiny distance between the read/write head and the disk's surface. Removable hard disks combine high capacity with the convenience of diskettes. High-capacity floppy disks are becoming a popular add-on for many computers. They offer capacities up to 250 MB and the same portability as standard floppy disks. Data cartridges are like small removable hard disks and can store up to 200 GB. Magnetic tape systems offer slow data access, but because of their large capacities and low cost, they are a popular backup medium. жүктеу/скачать 0,7 Mb. Достарыңызбен бөлісу:
|