By sxaling on 2006-6-9 21:34:00
, How many categories of departmental equipment are there by purpose? In addition to power supply equipment, list two typical devices in each category.
Answer: External equipment can be divided into eight categories according to its use. In addition to power supply equipment, external memory, including hard disk, floppy disk, etc., input devices, including keyboards, mice, etc., output devices, including monitors, printers, etc., office and CAD equipment, including scanners, plotters, etc., multimedia equipment, including sound cards, CD-ROM drives, etc., communications equipment, including network cards, MODEM, etc., buses, such as PCI, EISA.
2, the bus is divided into which two levels? What kinds of standards are included? (Each give two examples)
A: The bus is divided into system-level and device-level, the former contains PCI, EISA, etc., the latter includes IDE, SCSI (for disk and CD-ROM) and so on.
3. What is an interface?
Answer: Interface contains both hardware and software concepts. From a hardware point of view, the interface is a peripheral and host communication control components or circuits, it is located between the bus and the peripheral, usually placed on the side of the host, play a role in the conversion, transfer of data. From the software point of view, the interface is mainly a driver or configuration of the device.
4, what kinds of external devices?
A: See textbook P5, line 11.
5, the external device control program has which kinds? What is the role of each?
A: See textbook P6, line 15.
6, the keys on the keyboard according to the material points, what are the common ones?
A: The common keys are mechanical, capacitive and membrane type.
7, the keyboard control circuit includes which parts? What is the role of each?
A: The keyboard control circuit includes a microcontroller, decoder, keyboard matrix and serial port plug seat and other four parts. Microcontroller to provide scanning signals and receive key information, it is also responsible for sending serial data pulses to the host (key code) and synchronized clock, as well as contact with the host. The decoder will be sent by the micro-controller scanning signal decoding, that is, to the keyboard matrix output 13 different lines at the same time as the zero line scanning. Keyboard matrix consists of 8 columns * 13 rows (AT101, for example), rows and columns of the intersection were connected to the key of the two contacts, do not press the key, the column line output is high, there is a key pressed when the corresponding column line output is low. Serial port plug is used to realize the keyboard and host signal connection.
8, try to "h" key code input as an example of the keyboard operation process.
A: See textbook P12 line 20.
9, try to describe the operating principle of the keyboard interface circuit.
A: The keyboard interface circuit is connected to the keyboard via the serial data bus KBDDATA and the serial clock line KBDCLK. It will be sent to the keyboard serial scanning code into a parallel scanning code, that is, the data byte DB0-DB7 sent to the CPU, and request an interrupt processing to the host, this interrupt will activate the BIOS INT9H service function, so that the host to read and process the key information. Keyboard interface circuit is the core component of the 8042 microcontroller. On the one hand, it is connected to the keyboard through the serial cable, on the other hand, through the system bus and the host connected. It's pin T0, T1 for receiving the keyboard scanning code, pin P16, P17 by the driver to the keyboard to send the start signal; in connection with the system on the one hand, P11 used to send interrupt requests to the system, DB0-DB7 is sent to the host parallel scanning code, and through the pin A0, / CS, / WR, / RD connected to the system address and control bus, pin / RESETE to receive the system reset The clock X1 and X2 are connected to the system PCLK to generate the 8042's own clock.
10, KBD-DATA and KBD-CLK on the keyboard cable to transmit what signals?
A: These two lines are bidirectional signal lines. On the one hand, they are used as a signal line to the host to transmit data (KBD-DATA) and synchronization pulse signal line (KBD-CLK), and on the other hand, before the transmission of data, used to receive the host's control signals, a high level indicates that the keyboard is allowed to transmit a low level indicates that the system is not ready to notify the keyboard to stop the transmission of serial scanning code.
11, INT 9H keyboard interrupt the main role?
Answer: INT 9H is part of the keyboard interface, and the keyboard interface circuit to complete the interface task, its role is mainly to interpret the keyboard scanning code into the system signal and buffer data.
12. What is the function of INT 16H's 0 (00H)?
Answer: INT 16H No. 0 (00H) function is to read the current key buffer content, that is, read a key information.
13, according to P23 Figure 3-1 shows the CRT structure principle, try to explain the CRT working principle.
A: CRT is mainly composed of three parts of the electron gun, deflection system and fluorescent screen. Electron gun is responsible for the electron beam under the action of high voltage to the fluorescent screen. Fluorescent screen is coated with phosphorescent material on the glass surface, it is hit by the electrons that is luminous, the deflection system is used to control the direction of the electron beam, so that the electron beam hit in the specified position of the fluorescent screen. Electron gun also accepts the brightness of the adapter and contrast signal.
14, try to explain the meaning of raster, pixel, resolution and other terms.
Answer: the image of the monitor is composed of a single point of light, the light on the screen is composed of the smallest unit of the screen image, known as the pixel; point of light rapid movement of a strip of light called raster; resolution is a frame of the screen has a horizontal pixels and vertical pixels of the product, which is a sign of the clarity of the image.
15, color CRT display why use three electron gun?
Answer: color CRT monitor color by the three primary colors - red, green, blue, and each pixel on the fluorescent screen is also composed of red, green, blue three points of light, these three points of light by three beams of electrons bombarded by the light emitting, so the color CRT monitor has three electronic guns.
16, what are the characteristics of the LCD display?
Answer: LCD display power consumption, thin thickness, light weight, no radiation, is the direction of development of microcomputer displays. The current problem is the higher price.
17, display "attribute type" refers to what?
A: Display "attribute type" refers to the display mode. For monochrome text mode, the attribute indicates the foreground and background colors of the displayed characters, display intensity, whether blinking, etc.; while the color code is also indicated in the color picking text mode; in the graphics mode, the color of each pixel point is indicated.
18, please explain the meaning of video mode in video system.
A: video mode consists of a set of data used to describe the standard parameters of each part of the video system, including mode number (related to the following items), type (text, graphics), the number of colors, resolution, character matrix (such as 8 * 8, 9 * 16, etc.), refresh buffer address, the type of adapter.
19, please explain the principle and function of character generator in display circuit.
Answer: The character generator uses ROM to solidify the character dot matrix. The character display code is stored in the character generator ROM. Each character consists of a certain size of the matrix pixel points, each bit describes a point, with 1 on behalf of the white, with 0 on behalf of the Li, each character accounts for a number of rows, that is, a number of byte. when you need to call, from the refresh buffer to take out the characters of the ASCII code bytes, as a call to display the address of the character ROM, and then converted by the display of the clock a point a point of the serial output.
20, the display of the graphic mode and text mode where the main difference?
A: See textbook P31, lines 15-22.
21, dot matrix printer mechanism composed of which parts? What is the function of each?
A: Dot matrix printer by the character mechanism, the word car mechanism, the paper mechanism and the ribbon mechanism consists of four parts. Character mechanism will be converted into electromagnetic signals to the character data, sent to the coil to drive the print needle to hit the ribbon, resulting in the printing of characters. The word car mechanism to drive the print head for horizontal movement, so that the print head to print the characters by column, until a full line and then return to the beginning of the line. The paper mechanism is in the vertical direction by moving the paper line, after each line of characters printed, the paper further ahead, print the next line. Ribbon mechanism is equipped with a cycle of ink-coated nylon ribbon, ribbon relative to the word car and move, when the word car for horizontal bidirectional movement, the ribbon drive shaft rotates, so that the ribbon can be used evenly.
22, dot matrix printer circuit is the main work? It consists of which parts?
Answer: the main work of the printer circuit is: to accept the instructions and data from the host, return to the host of the status of the information needed and the response signal, drive the implementation of various agencies to initialize commands, print commands and self-test commands; to receive the control panel on the key commands and display the status of the printer on the panel information. Printer circuit has six parts, including interface circuits, control circuits, drive circuits, character generator, power supply circuits and DIP switches.
23, try to describe the working principle of inkjet printer.
A: inkjet printers that use jet ink droplets to print characters or pictures of the printer. It consists of a print head, ink cartridges, transmitters, high-speed rollers and print carts. Print head consists of a group of nozzles with a resistance filament, nozzle cavity contains ink, when the paper through the transmitter and print head between the nozzle in the resistance filament according to the composition of the character array energized and heated, the print head at this time the corresponding nozzle ink thermal expansion, sprayed to the print paper, the formation of print characters. Word car in the horizontal direction to move a line, complete a line of character printing, until a piece of paper all printed.
24, what are the interface signals of the printer?
A: In addition to the 8-bit data signal, the printer's interface signals include STROB #, which is issued by the CPU to select the signal; ACK #, issued by the printer to the CPU to answer the signal; BUSY, the printer to the CPU to issue a "busy" signal; PE, issued by the printer to the end of the paper signal; SELECT OUT, the printer to issue a signal. SELECT OUT, the CPU issued by the selection (printer) signal; AUTO FD #, the CPU issued by the automatic feeding signal; INIT, the CPU to the printer's initialization signal; SELECT IN #, was selected by the printer to the CPU issued by the on-line signal; in addition, a GROUND for the connection of adapters and printers with the public **** ground signal.
25, why is the INT 5H service function can be activated by hardware, but also by the program call?
Answer:: The program can be listed directly call the INT 5H function of the statement INT 5H, you can activate this service function; the user presses the keyboard PRINT SCREEN, that is, automatically issued an interrupt signal, the implementation of the INT 5H screen printing function; the latter belongs to the hardware activation.
26, try to describe the working principle of laser printer.
A: laser printer by the optical system, photosensitive toner cartridges, corona and electrostatic cleaner. First of all by the electrostatic precipitator will be charged on the cartridge and color powder to remove the completion of the print ready; followed by the main corona voltage to make the surface of the cartridge uniformly covered with negative charges; 3rd is laser scanning, from the computer to receive the character image data to be printed by the internal circuitry into pixel arrays, the optical system will react to the character image of the high level of laser beams, through the shaping, focusing, refractive scanning to the cartridge, cartridge is the place where the laser irradiated, the cartridge is Laser irradiation to the place, the charge quickly disappeared, and did not light to the place, the charge is retained on the surface of the drum to form a text or image of the electrostatic latent image; 4th is the toner developer, when the drum rotates to the toner cartridge at the toner by electrostatic attraction is suction commanded to the surface of the sensitized cartridge in the surface of the cartridge to form the text or image of the electrostatic latent image; Finally, paper through the toner cartridge, toner printed on the surface of the paper, paper Into the heater after heating, the toner dissolved into the paper, the output print results.
27. What is the role of INT 13H interrupt service in ROM BIOS?
Answer: INT 13H interrupt service is a service function in BIOS about the disk. Undertake the interface work of the floppy disk and hard disk. Mainly includes the system (soft, hard disk) reset, read the current operation status, read the specified sector to the buffer, write data from the buffer to the sector, check the specified sector, format the specified sector and many other functions.
28, please point out the characteristics of the IDE cable and the scope of application?
A: IDE cable standard software compatibility, high data transfer rate, wide range of applications, is the most popular cable standard. IDE adapter controller to do inside the drive, with a large storage capacity, fast access speeds, including error-correcting circuitry, pre-formatting, easy to install, inexpensive. It is suitable for both hard disk drives and optical disk drives.
29, try to read and write the structure and role of the magnetic head.
A: read-write head by the magnet core, coil, flux and read-write gap (see textbook P76 Figure 5-1). When writing data, the information to be recorded current through the coil, generating magnetic flux in the core. When the magnetic media and head gap contact, the flux will pass through the media and the formation of a closed magnetic circuit, so that the media is partially magnetized, and after the head still retains a certain amount of residual magnetism, the information is recorded. Read out is the reverse process of writing. When the head and the media for relative motion, due to the media and the head gap contact, so that the core of the original record of the scattered magnetic flux, and in the readout coil at both ends of the induced electromotive force, this induced electromotive force amplified by the readout circuit can be restored to read out the current, read out the direction of the current and the size of the original recorded signals with the original information to restore the original data to complete the process of reading out the data.
30, disk data read and write by which steps to complete?
A: floppy disk as an example, (see textbook P77 lines 5-10).
31, what are the differences and similarities between a floppy disk and a hard disk?
A: floppy disk and hard disk read and write the same principle. Each disk is divided into physical data areas by heads, tracks, sectors. Disk on the track format is also similar, such as 000 channels are stored in the directory, file allocation table and other content. Others, such as record format and error correction code, are also the same. The differences are: hard disk capacity than floppy disk is much larger, faster speed, more reliable performance, higher data transfer rate; floppy disk is a single disk, while the hard disk for the multi-disk, multi-head, can be divided into time can also be selected at the same time; floppy disk and drive can be separated from the hard drive and the drive is sealed together to increase the ventilation of the dust removal device; hard disk media strength is better than the floppy disk can be used to improve the coding technology, higher density of records; hard disk Positioning system and control logic is more complex, the head and disk surface movement is different, no write-protection device; both drive controller circuitry is different, the port registers and their commands are different, the cable standard is also different.
32, what is the role of the floppy disk adapter?
Answer: The floppy disk adapter is an interface component centered on the floppy disk controller. Its main role is to transfer the data to be converted, the system operation will be converted to drive the required signals, and return to the disk drive status for the system can receive information.
33, hard disk why the use of floating heads?
A: There are two reasons, one is because of the uneven surface of the disk, if the head collision with the easy damage to the disk surface; two is because of the high-speed rotation of the disk, the head and the disk surface is easy to wear and tear in the long term contact.
34. What are the characteristics of SCSI interface?
A: SCSI interface can transmit 8, 16 or 32-bit data, the transfer rate of up to 20MBps or more, you can simultaneously hang seven different devices (including hard drives, floppy drives, optical drives, etc.), widely used in small machines and high-end microcomputers. The disadvantage is that compatibility is not good, to use a specialized SCSI interface card, the price is higher.
35, disk files are usually divided into several regions? What do they represent?
A: Disk files are usually divided into three regions: (see textbook P113 penultimate three lines).
36. What is the meaning of Plug and Play? Give an example.
A: Plug and Play is an industry standard for automating the handling of PC hardware device installations. Plug and Play makes the installation of hardware devices is greatly simplified, do not need to do the jumper, but also do not have to use the software configuration program to set the I / O address, DMA, IRQ resources, etc..
For example, if you insert a newly purchased sound card into your motherboard, the system will automatically recognize the device and automatically configure it to load the driver and put it into use immediately.
37, what are the characteristics of the PCI bus.
A: PCI bus is actually a very practical system bus. It is a 32 or 64-bit data bus, a PCI interface with a special register to save the information on the motherboard, allowing the use of the program to configure the entire system. PCI has a plug-and-play characteristics, the use of the PCI bus controller, which makes any device with a microprocessor can be connected to the PCI bus. In addition, PCI address bus and data bus is multiplexed; PCI can be used to connect peripherals can also be connected to memory.
38, why disk drive cables to establish standards?
Answer: The cable standard for disk drive cables is also known as the interface standard. It has a great impact on the performance of the disk. The reason for the establishment of standards, one in order to improve the compatibility and versatility of disk drives; second, with the continuous improvement of disk manufacturing technology and performance, the corresponding cable standards must also be updated and upgraded.
39, floppy disk adapter circuit in the data separator and write pre-compensation circuit are connected to which two devices or components? What signals are converted to what signals?
Answer (see textbook P87, line 18).
40.What are the characteristics of serial communication?
A: Parallel port information is a set of signals on the bus at a certain moment, the transmission is the entire byte, in the transmission of the data form does not need to be converted. The serial port information is a string of time-dependent single sequence, that is, the information transmitted by bit, so the form of data between the system and the serial port need to be converted to achieve communication. In addition, the cable and protocol used for serial communication are also different.
41, FSK modulation mode how to demodulate? Please draw a simple schematic diagram.
Answer: demodulation is the opposite of modulation, FSK demodulator will be different frequencies of the two signals reduced to 1 and 0 two digital signals.
42, PC DTE can be used between other protocols of the serial interface standard (non-RS-232
standard)?
A: The RS-232C interface standard is commonly used for PCs. Now the popular USB can also be used for interconnection between PCs, but the USB pin signal also conforms to the RS232 standard. Industrial control PCs also use RS485 and other serial interface standards.
43, the serial port communication cable why use analog as the transmission signal?
Answer: digital signals directly transmitted by the length of the transmission distance is greatly affected by the length of the transmission distance, if the transmission distance is long, the signal attenuation, distortion is serious, and prone to error. Therefore, the serial port communication cable using analog (sine wave) as the transmission signal, which is also the serial communication can be transmitted over a longer distance of the mystery.
44, RS-232 port transmission packet format and parameters include which parts?
Answer: Including the start bit, data bits (5-8 bits), parity bit and stop bit *** 4 parts.
45, what is called multimedia?
A: The carrier of information is called media. Most modern information is in the form of a combination of text, sound, images or graphics. The carrier for the storage, processing, and dissemination of this information is called multimedia.
46, Explain the working principle of rewrite once read many times CD-ROM.
A: This type of CD-ROM uses acrylic resin as the base material, and a thin film of tellurium alloy is vaporized or sputtered on the disc. The recording of information is, will be focused into less than 1nm diameter laser beam irradiation on the disk surface, in the media burned a pit, used to record information. When read out, the information recorded is obtained because the reflectivity of light is different between the pits and the non-pits.
47. What are the main performance parameters of an optical drive?
A: There are formatted capacity, data transfer rate, access time, speed and interface standards.
48, explain the basic functions and uses of sound cards.
A: Sound card is an important multimedia device, mainly used for sound and music processing. It can convert the audio analog signal into a digital signal sent to the computer processing and storage, but also in the form of digital storage of sound reduction into an audio analog signal amplification output. It has the following functions: 1. include file functions, in addition to digitized audio files, but also images and text and other data files interspersed with them; 2. mixing function, that is, a variety of audio sources for mixing; 3. compression and decompression of sound signals; 4. speech synthesis; 5. voice recognition; 6. MIDI interface function; 7. and CD-ROM drives, game sticks and other interface functions.
49, multimedia technology in the compression and decompression technology to solve what problems?
Answer: multimedia involves a very large amount of data, especially the movement of the video image data is greater, if not compressed, the data storage and transmission of these data is extremely difficult to deal with, can not make multimedia practical. Therefore, in the multimedia, especially video image storage and playback must be used after the data compression and then decompression restore technology.
50, briefly describe the
relationship between the three MPEG standards (MPEGI, MPEGII, MPEGIII).
Answer: MPEG's three standards of compression ratio and resolution improved one by one, MPEG I can be applied to ordinary CD-ROM and 640 * 480 resolution monitor, MPEG II, MPEG III suitable for high-definition picture quality of the television, the resolution of 1600 * 1200.
51, digitizers and scanners, the same as and Where are the differences?
Answer: Both for the computer input device, can be sent to the computer through the serial port digital signals. The difference is: digitizers for graphics input devices, and scanners for image input devices.
52, briefly explain the working principle of the optical mouse.
Answer: (Textbook P167 line 11 onwards)
53, which are the main performance parameters of the plotter?
A: (Textbook P162 line 17 onwards)
54, scanner is how to convert optical signals into digital signals and sent to the computer?
Answer: the scanner consists of an optical imaging system, charge-coupled devices, mechanical drive components and analog-to-digital converters. Optical imaging system consists of a light source, mirrors or transmission mirrors, photoelectric sensors. When the image through the scanner, the light source irradiated in the drawing, resulting in reflected or transmitted light (for film originals), through the lens focus on the charge-coupled device, the latter will be converted to different intensity of the brightness signal into different sizes of electrical signals; saved in the charge-coupled device corresponding to the image pixels of the electrical signals, and then by the A/D converter circuit converted to digital signals, sent to the computer.