The screen went black after I dropped my Apple tablet. What happened?

Insufficient system memory leads to crash

· Let’s first clarify a concept. The memory we usually refer to refers to the system’s cache, which is what can be seen using the “Display Power” software. "Memory", this cache is usually relatively small, less than 1 megabyte. It is the cache area for data that will be used when the program is running in the mobile phone storage, memory card storage and machine's own system. When the mobile phone storage, memory card storage, machine itself It plays the role of a bridge when exchanging data between the system and the machine CPU. This bridge is often the culprit of machine crashes, and most machine crashes are more or less related to it. The memory we mention in the future is this "memory" and not "mobile phone storage". Everyone should pay attention! Mobile phone storage is equivalent to our computer hard drive. In mobile phones, it is the same as memory card storage. It is just a storage device, not a memory (there is an interesting phenomenon in mobile phones, that is, we call the storage part of the machine memory. This It has indeed misled many people). Okay, we understand what memory is. Next, let’s talk about why insufficient storage space on a mobile phone can lead to a crash.

· Let’s give an example first: Do you remember the old computers from the early years! Their hard drives are usually not very big. When we crazily store things in them and the hard drive is about to be filled but is not yet full (for example, there is more than 100 megabytes of space left), is this what happens to computers? That’s right! That's the blue screen. Why the blue screen? Isn’t there still 100 megabytes available? This starts with the principle of computer data storage: no matter what program the computer is running, it must read the relevant data used by the program from the hard disk and store it in the memory, and then the CPU will calculate it. The data used is taken out from the memory (it also passes through the "bridge" of the first-level and second-level cache that comes with the CPU. The role played by the first-level and second-level caches between the memory stick and the CPU is equivalent to the role of the memory stick in The hard disk plays the same role as the CPU and plays a role in accelerating data exchange). When reading data into the CPU for calculation, you must know that the CPU reads data from the memory stick much faster than reading data directly from the hard disk. This greatly Improved program execution speed. After the calculation is completed, the CPU executes the calculation result. For example, the calculation result is to execute an instruction: open the folder, then the computer will display the contents of the folder. For another example, we are typing a document. The computer's CPU calculates what text we type through our typing on the keyboard. Then it puts the text we typed there, that is, in the memory until we give it a command, let it "save" the text we entered, and then it will dump the content we entered from the memory stick to the hard disk. However, the fact is that the reason why a computer can run is due to the calculation of the CPU. All our actions, even the display on the monitor, including moving the mouse, must be calculated and directed by the CPU, and these calculations and commands are complex. Huge intermediate results are often temporarily stored in the memory stick. Only when the CPU thinks that the memory cannot be loaded, or we give the computer a command to save it, will it be transferred to the hard disk. During this process, the hard disk is always in use. Tells the spinner to be ready to receive data dumped from memory at any time. At this time, the CPU has to spare no effort to constantly detect the location stored on the hard disk so that it can be connected from this location the next time it is stored. When our hard drive is almost full, the remaining space often exists in the form of fragments, which further increases the difficulty for the CPU to detect the location of the hard drive. In addition, the previous CPU did not run very fast, and the memory stick It's not very big, so this kind of dump needs to be done frequently. This large amount of data exchange causes the CPU to perform crazy operations, which can cause a crash if not done properly. This is why computers often blue screen or freeze when there is not much space left.

·Okay, after talking so much about computers, it is just to bring the topic to our mobile phones. As mentioned before, the storage in mobile phones and memory card storage are both storage devices in mobile phones. It is not real "memory", it is just equivalent to the hard disk in the computer, and the real memory is "memory" with less than 1 megabyte of space (we can see this through the "display power" of the software, or in the file manager You can see it in "System Information") This "memory" is truly equivalent to the "memory stick" in the computer.

Having said this, it is already clear why mobile phones are more likely to crash when there is insufficient storage space. There are similarities between the smartphone system and the computer windows system. Compared with the computer blue screen above, there is no need to say more.

· Everyone uses OxiosHibernat, a software that releases memory. Have you noticed an interesting phenomenon? That is, no matter what situation you are in, no matter how slow your system is, no matter what program you use before releasing the memory, as long as you click OxiosHibernat to release the memory, the released memory will never exceed 888k, which is correct. Yes, because the "storage memory" itself is only 888k, how can you release more than it. Our famous memory release software releases the memory equivalent to the memory stick in the computer and the memory in the mobile phone, not the mobile phone storage and memory card storage.

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· The crash caused by improper operation can be avoided unless you have no experience in using computers. Although it is a smartphone, neither the operating system nor the CPU can be compared with that of a computer. Therefore, it is recommended that users use it in a single thread, which is best when the program is executing (when the "busy" symbol appears). ) Do not do other things. For example, your mobile phone is searching for pictures in your card. At this time, you press other buttons. Maybe you want to quit the search, but the persistent mobile phone must search to the end. The result of the stalemate between the two parties. Often it crashes.

· Too low an ambient temperature can cause a crash

· For a long time, the majority of computer enthusiasts have been debating whether the ambient temperature can cause a crash. The answer is yes, too low a temperature can indeed cause a crash. Cause crash! However, this is not a defect of the mobile phone. In fact, on the contrary, it is a self-protection function that is not clever. The windowsmobile2003 operating system has the function of detecting ambient temperature. The "thermometer" software we use relies on the Windows Mobile 2003 operating system to detect the temperature. In fact, it just reads the temperature detected by the operating system itself. It is not that the "thermometer" software itself can detect the hardware temperature. Some people say that the "thermometer" detects the temperature of the battery, which is one-sided. It actually finds the code in the Windows Mobile 2003 operating system that can determine the current and voltage of certain parts of the hardware, and measures the temperature through conversion. This code is controlled by hardware, which means that the voltage of this hardware is very sensitive to temperature. This hardware is usually a CPU or a "cache" (not memory, which is not what is usually called mobile phone storage). Of course, sometimes it is also a battery. . This is why "Thermometer" can be used on Windows Mobile 2003 on some mobile phones, but cannot be used on Windows Mobile 2003SE of some phone friends. The reason is that there is a big difference in the code segments between 2003 and 2003SE, and "Thermometer" is still in the original version. If you search for that piece of code, of course you won't be able to find it. Even if it is the same machine, if a battery of another brand is replaced, sometimes the temperature cannot be read due to changes in the code segment. It is this temperature change that causes the hardware current or voltage inside the machine to change, and the current or voltage change causes the system monitoring part to react. However, due to imperfect software design, it may be a mistake in the design, or it may be the designer. They have not considered at all, letting the operating system fend for itself, or even "crash" to resist the temperature and prevent the machine from continuing to run. This is indeed a big problem that system designers should solve! So why does the Windows Mobile 2003 operating system have to react to low temperatures? I don’t want to go into too much explanation. This involves the working principle of LCD and so on. In order for the mobile phone’s LCD screen to display normally, it must ensure that the mobile phone operates within a certain temperature range, so the operating system must monitor the temperature. The majority of machine enthusiasts can personally do an experiment and start the machine at a relatively low temperature (for example, below 5 degrees). After the screen of the machine loading system appears, the system detects that the temperature is too low and will automatically shut down and refuse to start, realizing self-starting. Protect.

· On the contrary, when the temperature is relatively high, such as above 24 degrees, or when sunlight directly shines on the screen, the machine's response speed is significantly higher, and the screen's response time is at least To shorten it by half, the display is completed almost at the same time as the key is pressed, without any lag! It is worth mentioning that the phenomenon of crash due to low temperature not only occurs during standby, but even in "airplane mode", it is still "dead"!

· Conclusion: No matter how strong your phone is, you must give it some warmth. When it crashes once due to low temperature, there will definitely be a second crash, and the crash temperature will be higher each time. In the end, the crash temperature may be so high that you can't bear it. Especially friends in the north should pay more attention in winter. It is best to put your mobile phone outside your underwear and don't hang it around your waist like a farmer.

· Unexpected hangs during standby

· Now it is the problem of unexplained hangs during standby. Most of the crashes during standby are caused by the software running mode of Windows Mobile 2003 operating system. We know that our mobile phones are usually used to make calls, which is also a priority for the software designers of the Windows Mobile 2003 operating system. Therefore, when the mobile phone is in standby, most of the mobile phone resources are allocated to the standby signal part first, while in addition On the one hand, the Windows Mobile 2003 operating system also needs to take into account our own DIY software. It must automatically search for information about the software we installed every once in a while, and record it through cache (note that "cache" is the "storage" mentioned earlier. Memory", not "phone storage"). If the record is long and complex, while the operating system is busy communicating with the base station signal, it also needs to search for machine information and make records, which may lead to a crash in standby. This is why there are software like OxiosHibernat that release memory (cache). Indeed, when the machine automatically reloads the searched information every once in a while, but the original information cannot be released, the cache (not referring to the mobile phone) Storage) space is getting smaller and smaller, and the probability of crash is increasing! This phenomenon is more serious on a few mobile phones, but due to the use of 2003SE and the increase in cache, this phenomenon has been reduced.

· So how to solve this problem? In fact, everyone knows it. Just pay attention to the order: first, hard reboot and restore factory settings. Then run it safely for 7 days without installing any software, without inserting the memory card, and in an environment where the temperature is at least higher than 15 degrees (the so-called safe operation means that a crash is not allowed in the middle, so it requires that the environment is shut down The temperature is not allowed to be lower than 15 degrees. Especially when turning on the machine in the morning, be sure to ensure that the body temperature of the machine is higher than 15 degrees. If there is a crash in the middle, it must be restarted and the number of days will be recalculated). The purpose of this is windowsmobile2003. When the operating system searches for its own software (in the system), it finds that there are no "intruders", that is, there is no software installed by the user (in the mobile phone storage and memory card storage) and makes a mark. After this mark is made, when the security period has passed and the user installs the software, the machine will search from below this mark, that is, only the mobile phone storage and memory card storage will be searched, and the search for the built-in software will be skipped. Otherwise, if we install new software immediately after a hard restart, then every time the machine is turned on, it will be thought that a large amount of newly installed software has been installed. Time automatically re-searches for new software information in all spaces, increasing the burden of machine search. The result is often that there are no problems at the beginning. As time goes by, our use of the software we installed becomes worse. New information) includes various information every time it is used, and this information often becomes garbage in the mobile phone. Most users often find that the memory of the mobile phone has become smaller, which is caused by this kind of information. The records of the original program are constantly being written, and when the system searches automatically every once in a while, the burden gradually increases. The worst result is that it crashes inexplicably during standby.

·During the safety period, users should pay attention to the "machine test". The so-called "machine test" means that you have to use the machine frequently during these 7 days. All functions that come with the machine, such as "games" , use all "shortcuts" and various settings to increase the system's familiarity with the software.

· When the safety period has passed, the memory card can be inserted and software can be installed on the memory card and the phone. From then on, every time the machine searches, it is actually only searching for software information in the memory card and mobile phone, and will ignore the search for the mobile phone itself. (I would like to emphasize one more point here: some mobile phones without memory cards also crash. The main reason is that the operating system is not familiar with the software enough. Pay attention to taking the test during the safety period, and it must be done after the safety period. Install the software into the phone storage). When we follow the above method and plug in the memory card, we can see an additional storagecard "storagecard" from the file manager. From now on, the machine will not actively search for it, so all installed in The icons of the software in the card will all appear in the same unrecognized label style after booting. Only when we give the machine a stimulus and order it to search for the information in the card will it search.

· We can do an experiment: shut down the machine first, then turn it on, press the left soft key "Start"/"Others"/"Others", you will find that all the software icons installed in the card are is an unrecognized label style. Then press "Home" to return, and then "Start"/"Others"/"Others". Similarly, why is the software in the card still labeled with an unrecognized tag! That's right, the machine does not actively search for software information in the card, and the amount of software information in the cache is reduced. Such machines are usually not prone to crashes. This is our purpose. So how to stimulate the machine to search? We can press "Others" and go to the last page, enter "Games", open "Ling Yun Zhuangzhi" to play, then close the game and return to the homepage. This time, look at the icons of the software installed in the card. How about the icons? Everything has turned into its original appearance. Why can playing "games" stimulate machines to search for program information again? First of all, this is a large game; secondly, this game comes with the machine. When we run this game, it takes up a lot of resources, which is what we usually call space. Of course, this "space" includes "cache", so when a large amount of data comes in, the machine has to store the program information that was originally searched. Clear it out, dump out the space, and go all out to ensure the game runs. When the game is over and the space is restored, the machine has to search for installed software information again. With this search, the information installed in the card is read into the cache, and the icon's appearance is restored.

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· Software problems

· Mainly due to fatal bugs in the software design of the mobile phone, which lead to crashes. For example, when the mobile phone runs a program When, if there is a logical error between the subroutine and the main program, an instruction error will occur whenever the phone runs the program, which is a bit like an illegal operation in a computer. At this time, there may be Crash. Crash caused by software bugs generally has the following characteristics: every time a certain command is run, that is, every time the same operation is performed, it will crash. If the mobile phone always freezes like this, you can initially It is concluded that the crash is due to a software problem. Such a crash can usually be solved by upgrading the software. However, such an upgrade can only upgrade the software version. After the upgrade, the functions of the phone will not change, but during the upgrade It has solved some software bugs and reduced the chance of crash. If you are not familiar with the software during the upgrade, it will cause instability to the phone. If you upgrade, please make a backup in advance to avoid the software not being able to be restored after the phone upgrade fails.