a) Monitors
Monitor (display) computer, IBM PC is designed to display text and graphic information. Monitors come in color and monochrome. They may work in one of two modes: text or graphics.
Text mode. In text mode screen conventionally divided into individual plots - znakomesta, mostly in the 25 lines of 80 characters (znakomest). In each znakomesto can be entered one of the 256 characters in advance. Those characters include large and small letters, numbers, certain characters, as well as psevdograficheskie characters used to display tables and charts, building a framework around the sites screen and so on.
Among the characters depicting the on-screen text mode,
can enter and Cyrillic characters. On the color monitor each znakomestu can match your color and background that allows you to display beautiful color labels on the screen.
On monochrome displays to highlight certain parts of the text and parts of the screen uses high brightness characters, underline, etc.
Graphical mode. Graphical mode is designed to display graphs, drawings and so on. Of course, in this mode, you can display and text information in the form of various inscriptions, and these markings can be arbitrary font, size, etc.
In graphical mode, the screen is made up of pixels, each of which can be darker or lighter on the monitor and one or more colors - in color. Number of points on the screen is called a resolution of the monitor in this mode. It should be noted that the resolution does not depend on the size of the screen monitor.
Frequently used monitors. The most widely available on computers IBM PC monitors were the type MDA, CGA, Herkules, EGA and VGA.
Currently, MDA monitors and CGA little used because they do not have good resolution, which leads to a rapid eye fatigue. In addition, they do not have the software download fonts characters, so images have to replace the Cyrillic letters chip that stores character fonts.
The main computer monitors use SVGA, which achieves the desired image quality.
b) Input Devices
Keyboard. As you know, the keyboard is still the main input information into the computer. In the technical aspect of this device is a combination of mechanical sensors perceived pressure on the keys and closing one way or another a circuit.
I must say that the evolution of keyboards for the IBM PC was short-lived. First used 83-x keyboards keyboard and then, together with an AT 84 x Key. Podovlyayuschee most of today's IBM PC compatible using an expanded keyboard. The main improvement in comparison with AT-keyboard regard to the total number (101 and above) and the location of keys. The most standard is the location of QWERTY: 60 keys with letters, numbers, punctuation marks and other symbols, and about 40 function keys.
The device keyboards. Currently, the two most common types of keyboards: mechanical and membrane switches. In the first case, the sensor is a traditional mechanism of contacts from a special alloy. Despite the fact that this technology is used for several decades, manufacturers constantly working on modifications and improvements. It is noteworthy that the keyboards known firms contact switches golden that significantly improves the electrical conductivity.
The technology, based on a membrane switch, is considered more progressive, although no special advantages.
Mouse and trackball. Mouse and trackball are koordinatornymi devices entering the information into the computer. Of course completely replace the keyboard, they can not. Basically, these devices have two, three buttons. It's no secret that his popularity is obliged to disseminate the mouse and the graphical user interface is mainly company «Microsoft».
Your mouse. As you know, the first mouse and ride two wheels that have been linked to the axles variable resistors. Moving a mouse was in direct proportion to change the resistance of variables rezi-hand. In the future construction pereterpela significant changes. Clips were moved inside the body, and contact with the surface was a solid rubber ball.
There are 3 ways to connect a mouse. The most common are connecting via a follower-mounted port. Less common mouse with shinnym interface for connecting requiring a special interface, or
«Mice» port.
A third variant can be considered as a mouse-style PS / 2
used in computers, a similar series, and are now the de facto standard for portable computers. To connect using connector miniDIN 6.
Physically, each mouse has a tail-type connector DB-9. In some cases, the adapter is set to DB-25.
Modern mice are usually the best hardware resolution of 400 cpi. When the company permission to declare the level of 1800 cpi, then it probably is a software authorization.
The device trackball. Trackball, generally speaking, is a «turn» mouse, a trackball driven not block, but his ball. This allows you to significantly improve the accuracy of the cursor.

b) External recording ustroistva
Floppy disks. Any computer (designed for serious work) is equipped with a so-called external memory. These devices are primarily drives on floppy disks (NGMD) and Hard Drive (NMD).
Pamyatiprednaznacheny external devices for the long-term storage of information. NGMD and NMD related to the magnetic disk memory devices, as well as information in these devices recorded at the rotating disk covered with magnetic material resembling the cover of conventional audio tapes and videotapes. And although its composition magnetic coating used in disk drives, different from ordinary household cover tapes, they used the same principle of recording information.
In normal household recorders to tape recorded analog signal directly from a microphone, the player records, CDs or other source. Computer records on magnetic disks bits of information. If you have to write a few bytes of data, all the bits of bytes stored in sequence on one track.
Tracks form on magnetic disks concentric circles. Block special magnetic heads moved to the radial axis to the center or the center of the disc, procherchivaya on the surface of the disc imaginary circles. The computer can arbitrarily set block magnetic heads at any track disc, but the data itself on the track has consistently viewed the computer as the rotation of the disc. Design NGMD implemented in a way that you can change the set of magnetic discs. Such removable magnetic disks known as floppy disks or floppy disks (also called disks) and placed in a special cardboard envelope that protect them from damage.
The floppy disks can not be heated, located near the strong electromagnetic fields (it is understandable why - information will be deleted). For better preservation of data, try to keep away from floppies powerful magnets and video. You can not touch your fingers to the surface of the disc, as you can contaminate her fat, which is always on the skin.
Currently used floppy disks of two types - a diameter of 5.25 "(Fig. 1.14) and 3.5 (Fig. 1.15). Depending on the design of the disc and a magnetic coating material, you can write on a floppy disk from 360 kilobytes to 2.88 megabytes of data. The most common floppy disks diameter 3.5 "and a capacity of 1.44 megabytes, a diameter of 5.25" and a capacity of 1.2 megabytes, and a diameter of 5.25 "and a capacity of 360 kilobytes.
The capacity of floppy disks can be determined from marks on the box. Here is a symbol to occur most often diskettes:

Designation
The diameter of a floppy disk, inches
The capacity of a floppy disk, KB
5.25 "2S/2D
5.25
360
5.25 "2S/HD
5.25
1200
3.5 "2S/2D
3.5
720
3.5 "2S/HD
3.5
1440
Diskettes diameter of 5.25 "and varying densities apparently virtually no different from each other, except that the floppy disk capacity of 360 kilobytes hole for a rotating shaft has a border around the edges. Diskettes have a capacity of 1200 kilobytes (or how to say, a capacity of 1, 2 MB) that there is no border.
The capacity of floppy disks diameter of 3.5 "can be easily identified by their appearance as a floppy disk capacity of 1.44 megabytes (1440 kilobytes) is a special hole to denote capacity. Diskettes a capacity of 720 kilobytes of such openings are not. Data recorded on a floppy disk, you can protect from accidental erasure or overwriting. In a floppy disk diameter 5,25 to do this zakleit hole write-protect with a special strip. A set of strips are sold along with the disks. In a floppy disk diameter of 3.5 to write-protect is a special kryshechka. With it, you can close the hole, thus protecting stored on a floppy disk data.
Streamers. We can not ignore, and this type of external device, such as storage on a magnetic tape or streamers. According to its principle of the devices resemble domestic cassette recorders. More often than not, streamers used to backup the contents of NMD, thus avoiding data loss at the exit of the NMD system. Most good streamers can be stored on a magnetic tape cassette with up to 2 GB of information, but because of the high cost of such streamer more prevalent streamers with a cluster, designed to record 150 or 250 megabytes of data.
in) CD-ROM
CD-ROM. How it works recalls the drive principle of the ordinary drives to floppy disks. The surface of optical disc (CD-ROM) moves on the laser head constant linear speed and angular velocity varies depending on the situation of the radial head. The beam of laser is directed at the track, focusing while using the coil. The beam penetrates the protective layer of plastic and coming into the reflecting layer of aluminum on the surface of the disc. When you hit it on the bench, he reflected on the detector and passes through a prism rejects it in the light sensitive diode. If the beam into the pit, it dissipates, and only a small fraction of the radiation reflected back and reaches the photosensitive diode. At the diode light is converted into electrical impulses, a bright light is converted into zeros weak - in the unit. Thus pit perceived drive as logic zeros, a smooth surface as a logical unit
Productivity drives CD-ROM. Productivity CD-ROM is usually determined by its speed in the continuous transmission of data over a period of time and the average time access to data, measured in Kb / s and ms. There are one, two, three, four, five, six and vosmiskorostnye drives for reading data at speeds of 150, 300, 450, 600, 750, 900, 1200 Kb / s, respectively. Currently available two-and chetyrehskorostnye drives. In general, with a four-speed drives have higher productivity, but to assess the net benefit of the drive with a four-speed compared with double-speed drive is not so simple. First of all, it depends on what operating system and with what type of applications being made. When high-intensity repeated access to CD-ROM and reading a small amount of data (such as when working with databases) "pulse" reading speed of information becomes important. For example, according to the magazine InfoWorld, performance drives with four speeds, compared to drives with twice the speed, in the case of transactions in the database, on average, increased by half. In the case of a simple copy of the data gains ranging from 10 to 30%. But the biggest advantage will turn out with full-length videos.
To increase productivity drives their supply buffer memory (standard cache: 64, 128, 256, 512, 1024 kilobytes). The buffer is the drive is a short-term memory for storing data, after reading them with a CD-ROM, but before sending it in charge controller, and then in the TSP. This buffering allows disk device to transmit data to the processor in small portions and not take it, the slow transfer constant flow of data. For example, according to the requirements of the standard MPC level 2 CD-ROM drive is twice the rate should take no more than 60% CPU resources.
An important feature of the drive is the buffer, which affects the quality of animated images and videos. It is defined as the ratio of the number of blocks of data sent in a buffer of storage and kept it until the start of their extradition to the system bus, the total number of units that can accommodate buffer. Too much filling can lead to delays in the issuance of a buffer to tire with arch hand, the buffer is too small degree of fill will require more attention from the processor. Both these situations lead to spikes and disruptions images during playback.
IV printers and scanners
Printers. Printers used to display the results of the (press). There are currently using four fundamental circuit causing the image on paper: dot matrix, inkjet, laser, termoperenosa. In matrix printing Printing heads hit needles on paper through the color tape, the image is formed in the form of points. In inkjet printing Printing heads off through the thin nozzle ink to paper. When laser printing surface of polarized laser printer drum, which sticks fine particles krasyaschego powder. The paint is applied to paper and heat vpaivaetsya in its surface. When termoperenose heats the surface of the special paper, and points heating changes color from white to black. In order to accurately chart patterns, drawings used plotter. There are tablet and drum plotters. A computer controls the special pencil to draw the line on the surface of paper. In planshetnom pencil moves over the surface in two directions; rolls just across the roll of paper and paper-back moves forward.
The classification of existing types of printers:
Matrix printers.
When we talk about matrix printers usually have in mind the impact device, such well-known models of Epson, Star and Microlin.
A coherent matrix printers, a number of vertical needles (or 2-row), or hammers, tape peg with the dye directly into the paper, forming strings of a symbol. Needle have an acceptable print quality, low price of consumables and paper, and the devices themselves. For these printers generally can be used as a format, and Roll paper. The head printer can be equipped with 9, 18 or 24 needles.
There are models of printers as broad (A3) and narrow (A4) carriage. High-quality printing is achieved in the modes NLQ for 9-needle (about typing) and LQ - to 24-needle printers. Print speed for vysokoproizvodi -
tional models can be up to 380 characters per second. A high performance ensure the progressive (paginal) matrix printers. Instead, small dot-matrix heads, they use long arrays with a large number of needles while the speed of order 1500 lines per minute. Matrix drums printers create a lot of noise, and this share, an important factor when choosing a printer.
Inkjet printers.
Refers to unstressed printing devices. These devices are virtually silent. Ink jet printers belong to the class of consecutive unstressed matrix printers. They in turn are divided into the device of continuous and discrete steps. The latter may use either the technology bubble, or pezoeffekt. Almost every modern device of this class are using two recent technology. When you print high-quality output speed does not exceed the usual 2-3 (about 200 characters per second), while the maximum can reach even the 7 pages per minute. Typically inkjet printers can emulate the work of the most popular models of shock devices and maintain the software.
Laser and LED - printers.