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optical drive, the fault can be eliminated. Common Failure VI: optical drive when reading data, sometimes can not read, and read the disk time to become longer Optical drive Read disk hardware failure is mainly concentrated on the laser head assembly, and can be divided into two cases: one is the use of too long to cause the aging of the laser tube, the other is that the surface of the photoelectric tube

I. Basic Concepts Its main function isCurrent Amplification(Analog circuit) andSwitchFunction (digital circuit ). A transistor is composed of two PN knots, and a shared electrode becomes the base pole of the transistor (represented by B ). The other two electrodes are the collector (in C) and the emission pole (in E ). Due to different combinations, a transistor is formed, which is a type of PNP and a type of PNP. Transistor is mostly Plastic Encapsulation or metal encapsulation, the appearance

supplies and motor drives. In the following introduction, NMOS is also used.A parasitic diode exists between the drain pole and the source pole. This is called a body diode, which is very important in driving inductive loads (such as motors. By the way, the diode only exists in a single MOS tube and is usually unavailable in an integrated circuit chip. It is the structure diagram of the mos tube, which is

while changing the T1 and T2.The first two methods, which change the period (or frequency) of the control pulses at the speed of the control, will cause oscillation when the frequency of the controlled pulses is close to the natural frequency of the system, so these two methods are seldom used. At present, in the control of DC motor, the fixed frequency method is used mainly. Reversible PWM control system with bipolar drive of DC motorBipolar drive refers to a PWM cycle, as the pulse voltage at

using MOS tube, but its principle is the same, that is, here with susb# control Pson grounding, In the form of switch tube to complete the electricity) First step: Pre-overhaul preparation First troubleshoot the primary power supply. Connect the power, press the boot key to boot. If no power is available, disconnect the rear cover of the chassis, unplug the ATX power cord, and use tweezers to short green

minutes to show up.This is caused by the leakage of the image tube seat and the tube seat must be replaced. The rear cover can be opened to see a small circuit board at the end of the image tube, and the tube seat is welded on the circuit board.On Carefully unplug the circuit board, then weld the

video card driver first, it is best to update to the latest version to try. Not really, consider whether there is a problem with the video card. 　4, monitor problems If the monitor itself has a problem, it can also cause the computer monitor to splash screen. According to the above 4 kinds of conditions, conditional friends may wish to use the substitution method test, can generally find the problem. The following are some computer maintenance staff summed up some of the reasons and solutio

the time of the disk becomes longer Optical drive failed to read disk hardware fault is mainly concentrated in the laser head components, and can be divided into two kinds of situations: one is used too long to cause the laser tube aging; the other is the photoelectric tube surface too dirty or laser tube lens too dirty and displacement deformation. So when the

Common fault One: the computer just opened the screen of the monitor jitter very badly, sometimes even the icon and text can not see clearly, but after one or two minutes will return to normal. This phenomenon occurs more in humid weather, is the cause of damp inside the monitor. To completely solve this problem, you can use the moisture-proof sand in food packaging with cotton thread string, and then open the rear cover of the monitor, the moisture-proof sand hanging in the image of the

normal. This phenomenon occurs more in humid weather, is the cause of damp inside the monitor. To completely solve this problem, you can use the moisture-proof sand in food packaging with cotton thread string, and then open the rear cover of the monitor, the moisture-proof sand hanging in the image of the tube neck near the tube seat. In this way, even in humid weather, there will be no more "problems".

First, the principle of DC circuit (1) Buck type converter Brief analysis: During the opening of the switching tube s, the current is charged to the capacitance C through the switch tube and inductance. When the switching tube s is off, the filter capacitance C is charged to r, because the inductor current cannot be mutated, through the RC circuit, D discharge

Common fault One: the computer just opened the screen of the monitor jitter very badly, sometimes even the icon and text can not see clearly, but after one or two minutes will return to normal. This phenomenon occurs more in humid weather, is the cause of damp inside the monitor. To completely solve this problem, you can use the moisture-proof sand in food packaging with cotton thread string, and then open the rear cover of the monitor, the moisture-proof sand hanging in the image of the

A 5-Philosopher's dining problem Semaphore fork[5]; for (int i=0;i This solution will cause a deadlock. To avoid deadlocks 1. Allow up to four philosophers to fetch forks at a time 2. The odd number first takes the fork on the left hand side, the even number first takes the right hand side fork 3. Each philosopher takes two forks at hand to eat, or a fork does not take Semaphore fork[5]; for (int i=0;i void philosopher (int i) { If i mod 2==0 then { P (fork[i]); Even philo

reaction speed is slow and the service life will be affected after a long period of use. Mos adds some simple method of resistance and capacitance delay lines, which is cost-effective and suitable for low-end applications. The best method is to use a hot swapping chip. Generally, the chip contains a drive MOS design and current detection resistor. In addition to basic hot swapping, it can also provide special functions, such as controlling the current rising rate, power supply management, and s

damage, can not be repaired, Another point is that your BIOS file must be consistent with your motherboard model, including the manufacturer and model, otherwise the refresh will often cause the phenomenon of not showing. Motherboard point does not light maintenance example Example 1. A pci1600-f motherboard is not lit. First of all, visual inspection, found that the Power control IC U24 (AIC1569) surface has burned traces, welding U24, check the peripheral circuit did not see abnormal. The b

the parsed form of the magic file, use in conjunction with-m to debug a new magic file before installing it -E,--exclude test exclude test from the ' list of ' test to is performed for file. Valid tests Are:ascii, Apptype, compress, elf, soft, tar, tokens, troff -F,--files-from file read the filenames to is examined from file -F,--separator string use string as separator instead of ': ' -I,--mime output MIME type strings (--mime-type and --mime-encoding) --apple Output the Apple Creator/

), cc = values (bb) + values (cc) This method determines whether the primary key or unique value exists before insertion. After values, multiple records can be followed. If not, insert data in batches. If yes, update the data. The update rules can be customized. cc = values (bb) + values (cc) 2. Use replace into tab (),(),.. Replace into table (aa, bb, cc) values (xxx, xxx, xxx), (ooo, ooo,

);Start_x =-1, end_x =-1;For (I = 0; I For (j = 0; j If (Map [tile_num (J, I)] = 's') map [tile_num (J, I)] = '', start_x = J, start_y = I;If (Map [tile_num (J, I)] = 'E') map [tile_num (J, I)] = '', end_x = J, end_y = I;}Assert (start_x> = 0 end_x> = 0 );Dis_map = malloc (map_w * map_h * sizeof (* dis_map ));Assert (dis_map );Return 0;} Void showmap (){Int I, J;Clrscr ();For (I = 0; I Gotoxy (1, I + 1 );For (j = 0; j If (Map [tile_num (J, I)]! = '') Cprintf (" O ");Else cprintf ("");}Gotoxy

Description:When a client requests a Web page through a proxy, the specified proxy server checks its own cache and, if there is already a page in the cache that the client needs to access (Red 1 2 3 4), directly feeds the page content in the cache to the client, or if there are no pages in the cache that the client needs to access (Blue 1 2 3 4), The proxy server sends an access request to the Internet, and when the returned Web page is obtained, the Web page data is saved to the cache and sent

" "): Puts (""); the } - } $ intMain () { the intT;SCANF ("%d",T); the intI, J; the while(t--){ thescanf"%d",n); - init (); in for(i=0; i"%s", Mp[i]); the for(i=0; i) the { About for(j =0; jif(mp[i][j]=='X') h[i]++; the if(h[i]==n) stack[top++] = i+N; the Else if(h[i]==0) Yes[i+n] =-1; the } + for(i=0; i) - { the for(j =0; jif(mp[j][i]=='O') l[i]++;Bayi if(l[i]==n) st