Sunday, October 24, 2010

80386 interrupt and exception



In addition to maintaining 8086/80386 80386 related functions, but also enhanced interrupt handling capability, and the concept of "exception" concept. This article will introduce the 80386 interrupt and exception mechanism. Download the article all the source code.

8086/8088 to break into the internal interrupt and external interrupt two categories. In order to support multi-tasking and virtual memory and other functions, 80,386 external interrupt known as the "break", the internal interrupt as "abnormal." As with the 8086/8088, 80386 usually between the two commands to respond to interrupt or exception. 80386 handle up to 256 interrupt or exception.

1. Interrupted

On the 80386, the interrupt is caused by asynchronous external events. External events and interrupt response and is not related to the implementation of the directive. Typically, the interrupt to indicate I / O device has completed an operation. As with the 8086/8088, 80386 INTR and NMI are two pins accept external interrupt request signal. INTR accepted maskable interrupt request. NMI received interrupt request can not be shielded. In 80386, the flag register IF flag in EFLAGS to decide whether screening can shield interrupt request.

External hardware through an interrupt request signal INTR the same time, but also to give an 8-bit processor interrupt vector. Processor in response to maskable interrupt request, read the paper by the external hardware interrupt vector number. Processor interrupt vector of this number and does not provide. But in the specific computer system, the system must meet the set of software and hardware, so given the interrupt vector number corresponds not only with the external interrupt sources and interrupt vector number used to avoid the appearance of conflict. 8259A programmable interrupt controller chip can work with the 80386, can be set to the processor according to the interrupt vector number, can handle the priority interrupt request. Each 8259A chip can support 8 interrupt request signal, if you use 9 8259A chip (a master piece, eight from the film), would enable a single pin INTR 80386 accepted up to 64 interrupt sources, interrupt request signal .

Processor does not mask the interrupt request from the NMI. Processor in response to NMI interrupt is not received from the external hardware interrupt vector number. And 8086/8088, as in 80386, the non-maskable interrupt the corresponding interrupt vector number is fixed at 2. For non-maskable interrupt nesting, when receiving an NMI interrupt, the processor again in response to the internal shielding of the NMI, the implementation of the screening process until after the end of the interrupt return instruction IRET. Therefore, NMI handler should be the end of IRET instruction.

2. Exception

80386 instruction exception is detected during the implementation of irregular or illegal conditions are present. Abnormality in the execution of the instructions have a direct link. For example, the implementation of the divide instruction, the divisor is equal to 0. Again, the implementation of instruction privilege level is not correct when found. When these situations occur, the directive can not be completed successfully. Software interrupt instruction "INT n" and "INTO" also classified as abnormal and not interrupt, because the implementation of these instructions produced anomalies.

80386 identify a variety of different types of anomalies, and to give each category a different interrupt vector number. After the exception occurs, the processor so as to respond to interrupt handling exceptions. That under the interrupt vector number, switch to the corresponding interrupt handler. This interrupt handler is called the exception handler may be more appropriate.

Abnormal according to whether the procedure caused the restoration and recovery point can be different, to be further classified as abnormal fault (Fault), trap (Trap) and suspension (Abort). We were the corresponding exception handler is called fault handler, trap handlers and termination handlers.

Failure is caused by abnormalities in the instruction before it is notified to the system anomaly an exception. That the fault is 80386 can be excluded. When control is transferred to the fault handler, the saved CS and EIP values break point to lead to failure of the command. Thus, the fault handler to troubleshooting, the implementation of the IRET to return to the program caused by failure to execute, just lead to failure of command can be re-implemented. This re-run, no additional operating system software to participate. Failure of the findings may begin before the command may also be in the instruction execution period. If failures are detected during instruction execution, then the suspension of fault instruction, and instruction operands to restore the value before the instruction started. This will ensure the re-implementation of fault instruction to get the right results. For example, during the execution of an instruction, if we find there is no section, then stop the implementation of the directive, and notify the system to produce Fault, the corresponding segment fault handler can load the troubleshooting section of way, after which the original instruction can be successfully implemented, at least not non-existent fault segment occurred.

Trap is caused by abnormalities in the following instructions to inform the anomalies An exception to the system. When control is transferred to the exception handler, the saved CS and EIP break point to lead to trap the value of the next instruction to execute instructions. The next instruction to be executed, not necessarily the next instruction. Therefore, the trap handler does not always save the breakpoints according to the anti-push identify an exception instruction. When the trap handler in turn, lead to the completion of trap instruction to be normal, it is possible to change a register or memory cell. Software interrupt instruction, single-step exception is the example of the trap.

Suspension is a serious situation in the system, an exception notification system. Caused by the suspension order can not be determined. Produce termination, is the implementation of the program can not be reinstated. System receives the suspension, the processing procedure to re-establish the system forms, and may restart the operating system. Hardware failures and system tables in the illegal value or inconsistent value is suspended example.

3. Priority

In an instruction execution period into more than one interrupt is detected, or abnormal, then press the priorities listed in the table notification system. The highest priority interrupt or exception notification system, other lower-priority exception being abandoned, while the higher-priority interrupt will remain hanging.

80386 responses

Interrupt / exception priority interrupt / exception types the highest priority fault other fault 鈫?debug trap instruction INT n and INTO 鈫?鈫?NMI debug trap minimum disruption 鈫?INTR interrupt







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Monday, October 18, 2010

Mocha further prosecution of the North Tower "Nine Questions" cocoon



Recently, the North Tower Software has released an article entitled "North Tower Software Mocha on the infringement question nine companies" article, the article in the North Tower with a very straightforward language Mocha protect their rights on a comprehensive question, while continuing to Mocha is accused of Rights of speculation. For the North Tower of the many doubts, Mocha software, today held a special press briefings, also invited a number of industry-leading media in the conference, and activists to conduct a detailed explanation.

As we all know, early in October this year, Mocha experience of their products because of suspected plagiarism, and will work with vendors and the North Tower to court. Initially, the Mocha software to non-named published an official statement means. Why non-named for the way, Mocha software Zhong Ping, Deputy General Manager, said: "Out of respect for and protection of those involved, our company adopted a non-official statement released in the form named, is intended to alert the industry, promote fair competition. However, we can not accept that statement 1, North Tower, directly to the Division I characterized as acts of legitimate speculation Rights, for such a ridiculous allegation, we can no longer bear patiently, only to issue a statement once again clear that the Division I the object of litigation for the North Tower. "

It is because of the North Tower of this practice outright, Mocha directly to the court "case acceptance notice" in the form of a statement issued screenshots. So far, the official North Tower suddenly silent, but constantly through the media insinuating accusations Mocha Rights in the hype. Until early December, the North Tower was through the media that the prosecution against their corporate reputation Mocha and has been placed on file in the court, while with the case did not make any disclosure of other information. Immediately following the announcement, it is no longer below the North Tower, has been so far.

At the same time, in view of the North Tower of speech and expression here, Mocha has already begun to make an additional claim of the plan, but taking into account the increase in new claims court and submit new evidence of limitation has expired, and Mocha decided to drop the be prosecuted. Just at this time, the North Tower on December 25 and then to "9 Q Mocha" form, issued an official voice. And accused the Mocha "four noes and one not" (no call, no explanation, no clarification, no apology, all right).

For the North Tower of the "Nine Questions", GAO Zhong-ping said: "This statement is totally unreasonable, even ridiculous. First of all, Mocha software may be against their own interests, to take the legal means to protect their rights that practice is normal and legitimate, is understandable, we do not need any person other than the court, any agency of any description, but do not make any clarification on any company with an apology; Second, Mocha is not the withdrawal of foreign informed , the primary consideration has been speculation the ground before the other side to attack us, in view of this, we used to avoid each other again, and has adopted a low profile and Tolerance attitude, but the other side we have the patience to shift as a symbol of their powerful This is ridiculous, and also is the disdain. "

Zhong-Ping, Mocha withdrawal is not to give up rights protection, on the contrary, not only will not give up Rights mocha, it will increase the claims and efforts to increase rights protection. In particular, progress in the course of this case, the North Tower of the number of irresponsible statements and actions already on the goodwill of Mocha causing serious injury, which further strengthened the confidence of Mocha continue to defend their rights. Based on this, taking into account the increase in new claims and new evidence submitted by the deadline, in full communication with the legal profession, the Mocha software decided to drop the prosecution will be present, Mocha has collected sufficient evidence, then Mocha will interface on the North Tower concerning alleged plagiarism and inappropriate comments after the North Tower adverse impact on the Mocha be investigated.

For the North Tower in the "9 Q Mocha", the accused Mocha's to create a "court of public opinion," "above the law," "distorted" and other statements, GAO Zhong-ping said: "This is not based on, can not stand live foot. mocha reiterated Mocha All Rights acts are based on a high degree of similarity between the two interfaces based on the expanded, Mocha did not have any business with any personal attacks, but do not involve above the law. As the industry standardization of legitimate businesses, Mocha know what to do, not what to do, but any attempt to infringe rights Mocha, fish in troubled waters, the purpose for doing nothing and are all futile, it is intolerable to Mocha . mocha defenders not only will not give up, it will increase the intensity of Rights, is now, the future will be like this! "

In addition, North Tati to the Mocha against the issue of its corporate reputation, high-Zhong Ping, said: "Prior to North Tower in the media, the date of this news release, our company has to prepare for active responding, and look forward to the Court of justice decision. But until today, I do not know why, our company has not received the Division I North Tower prosecution 'against its corporate reputation' legal documents related to the case, but considering the company will not easily take any legal problems as child's play Therefore, we have been not that we do not receive the relevant overseas law but is still awaiting the court's notice. but the North Tower on the matter already danced to this, we feel angry. "

Meanwhile, the high-Zhong Ping Ban jokingly, asked: "If there really hype Mocha meaning, it seems more should choose HP, IBM vendors such as objects, it is easier to become famous overnight, but there is no need to choose a small domestic manufacturers. North Tower from the beginning of the unlatched facts regarding the word about whether the alleged infringement, to continue to attack first, now Mocha is speculation, then Mocha 'against its corporate reputation' grounds of anti-reported Mocha, and to end Division I drop the question, we really do not understand the company's North Tower, what is the real purpose of this? "

"No matter what happens, as a standard IT solution provider, Mocha software in line with 'international technology, localization services, customer first' philosophy, will always continue to provide sustained, stable, safe, high quality services, with their unremitting efforts to develop China's software industry to do its part. "Zhong-Ping last made such a stress.

Description of the meeting in Mocha, Mocha Hou Jun, director of software products also involved Mocha BSM interface, the interface with the North Tower BTIM did a full explanation and comparison. According to him, Mocha business service management dashboard interface and an automated early warning mechanism for handling the incident as the core, truly to CMDB as the core of the operation and maintenance system for the establishment, operation and maintenance will help IT staff faster, more accurate treatment of accident to help IT managers set up a department from accident to accident settlement and the formation of experience and knowledge of the operation and maintenance mechanism, this mechanism can be tracked, can be found, can be controlled. The Mocha BSM host real-time dynamic operation interface is largely enhanced human-computer interaction. Which products to increase the deployment wizard-style configuration, drag-style mode of operation, visualization management system, to create personalized work space applications and other key features are due to human-computer interaction considerations.

Not difficult to see, this involved a visual management interface Mocha BSM host real-time dynamic operation interface is Mocha software breakthroughs in many aspects of human-computer interaction point. The deceptively simple UI interface, but from the unique design concept and product design system, the interface shows a different way will also have a very different user experience.

From this, the industry has been hit more than two months, "Mocha North Tower of the dispute", it seems only just begun. Not only because of the further prosecution of mocha, but because the North Tower of the "guerrilla" tactics. Appears in the press, as with the vendors and everyone seems to focus on products should be technology innovation, product marketing, corporate brand sublimation on. After all, the market is an objective reality, regardless of "reference" or "speculation" worth mentioning are unable to achieve a qualitative breakthrough.







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Sunday, October 10, 2010

Cleverly hide an important part of the worksheet so that no leakage



In practice, it often needs to be some important work sheet to hide, but many of my friends in the hidden worksheet are based on the menu "Format / Sheet / Hide" to complete, do you not know that hidden worksheet, for Little Excel's people, is basically useless, because we can also use the "Format / Sheet / Unhide" to be displayed, then how can it be truly hidden?

In fact, very simple, follow these steps:

1, select the menu "Tools / Macro / Visual Basic Editor" command, open the Microsoft Visual Basic window, on the left you can see the "project" and "Properties" panel.

2, in the "Project" panel, select the worksheet to be hidden, and in the "Properties" panel, set the "Visible" property value "2-xlSheetVeryHidden".

If set to 0-xlSheetHidden compared with the general hidden through the "Format / Sheet / Unhide" can still be canceled.

3, Select "Tools / VBAProject Properties" command, open the "VBAProject Project Properties" dialog box, select "Protection" tab, check "Lock project for viewing", and set the view properties of the project password, click "OK" button.

4, press Ctrl + S to save the file, return to Excel interface, you can see the worksheet has been hidden. At this point the menu "Format / Sheet / Unhide" is also in the gray state. Even if people know this way, no password is also not show the hidden sheets and immediately try it!







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