Virtual drivers and virtual Windows engines.

Virtual drivers are used primarily for hardware virtualization, ie, to provide simultaneously performed tasks sharing capabilities of the computer. Measuring and control equipment that connects to a computer in order to create an automated installation is unlikely to be used in a multi-tasking, but its use for the control of virtual drivers can significantly reduce software costs and to reduce the response time. Consider the example of a virtual device driver, the service interruption from the interface board timer counter. It is obvious that the composition of such driver shall enter an interrupt handler from the board. The functions of the processor determines the programmer, in the simplest case, the handler can just read the data from the output of the counter register and the interrupt mask. However, the application is not the completion of the measurements, is more natural to arrange a call from an interrupt handler driver of a function application, which can be passed to the read data. In fact, this function will play the role of the interrupt handler applications, but it will not be called by the interrupt handler and driver.
Virtual Engines in Windows
When Windows is run in verbose mode, the system creates a virtual engine, in which all applications run Windows. The system virtual engine is running in protected mode. For each DOS session started again creates a separate virtual engine running in a virtual processor mode V86.
Each virtual engine has a virtual processor register set and its own address space.
System virtual engine also has a table LDT, wherein only one. This means that all Windows applications run in the same address space. This fact facilitates the exchange of data between applications, because it is possible to create a global memory block that is available to any application, but greatly reduces the security of Windows applications from each other. And in fact, the majority of errors in applications for its manifestation lead to having to restart the entire system.

The memory structure in the virtual engine MS-DOS

Date: 2015-01-29; view: 1101