What is the virtual positioning software for nailing punch cards?

The first software is false positioning, which is foreign software and is divided into root mode and non-root mode. The second Ren Woxing, he was born specifically for nailing punch cards. The last software is called multi-open, which is mainly used for multi-open.

First, the virtual address is when the Windows program runs in 386 protected mode, so the logical address used by the program to access the memory is called the virtual address, which is similar to the segment address in real address mode. The virtual address can also be written in the form of "segment: offset", where segment refers to the segment selector.

Windows 2000 uses virtual memory based on paging mechanism. Each process has 4GB of virtual address space. Based on paging mechanism, part of this 4GB address space is mapped to physical memory, part to swap file on hard disk, and part to empty. All virtual addresses in the 4GB address space are used in the program. To access physical memory, you need to use a physical address.

Second, for the virtual address to be converted into a physical address, the CPU first finds the physical page where the page directory is located according to the value in CR3. Then, according to the value of 10 bit (highest 10 bit) of the virtual address from 22nd bit to 3rd bit, the corresponding page directory entry (PDE) is found, and the page directory entry contains the physical address of the page table corresponding to the virtual address. With the physical address of the page table, the corresponding page table entry (PTE) is found according to the values from 12 to 2 1 bit of the virtual address, and the page table entry contains the physical address of the physical page corresponding to the virtual address. Finally, the physical address corresponding to the virtual address is obtained by adding the lowest 12 bit of the virtual address, that is, the offset within the page, to the physical address of the physical page.

3. The calculation process of converting a virtual address into a physical address is that the processor finds the physical page where the current page directory is located through CR3, takes the height 10 bit of the virtual address, and then shifts the 10 bit to the left by 2 bits (because each page directory entry is 4 bytes long, and shifting 2 bits to the left is equivalent to multiplying 4) to obtain the address in the page, and takes out PDE(4 bytes) at this address. Find the physical page where the page table corresponding to the virtual address is located, take the 10 bit from the1bit of the virtual address to the 2 1 bit, and then shift the 10 bit to the left by 2 bits (because each page table entry is 4 bytes long, shifting 2 bits to the left is equivalent to multiplying 4) to get the address in the page, and take out the PTE (at the address)