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In order to save basic memory, the program to be edited also loads the extended memory, which is also operated by a handle. During the editing of the program, the program to be edited is loaded into the physical page of the high-end memory in turn from the logical page of the extended memory, and the editing of all the programs is performed in the high-end memory, thereby ensuring that the basic memory is not occupied during the program editing process.
Since both the edited program and the running program operate on the extended memory through the high-end memory, there is a problem of resource competition. In the system, the extended memory is operated by the handle. The logical page of the extended memory is managed by the EMM386.EXE file. As long as the handle of the corresponding extended memory can be applied, the logical page of the extended memory can be used without conflict. . In the high-end memory, there are a total of four pages of physical pages of 16k per page, and these physical pages are allocated. The program interpretation operation uses the first page, and the program editing uses the second page, since the EMM386.EXE program itself can guarantee the 67H interrupt. Re-enter the problem, through such a memory allocation method, solves the problem of expanding memory resource competition [3].
5 Conclusion
The author uses the extended memory of the system to realize the interpretation of a huge number of NC programs in the CNC system. The NC interpreter and editor based on the system's extended memory make the size of the running and editing programs independent of the underlying memory, and only related to the extended memory. The computer's configurable expansion memory is getting bigger and bigger, and now it can reach 256M. At present, the 8M extended memory can meet the requirements of the general NC program running and editing, which provides a loading and interpretation operation for more complex part processing programs. More convenient. At the same time, in the multi-channel CNC system software, the interpreter and editor can increase the number of channels in the multi-channel CNC system by increasing the memory overhead of up to 20k to 30k for each additional channel. Control more independent processes, which also has a certain significance for the implementation of FMS and CIMS. The NC code interpreter designed by this method has been applied to the Huazhong I type CNC system.
references
[1] Huang Shan, Wan Yudan. All the analysis and programming inspiration of DOS. Beijing: Xueyuan Publishing House, 1993: 85~87
[2] [US] TerryDettmann, Xiong Guixi, Lu Yimin, Li Junying, etc. DOS Programmer's Reference Manual. Beijing: Tsinghua University Press, 1996: 158-162
[3] Xiong Qingping, Sun Liansheng, Liu Yanqi. CNC real-time multitasking operating system. Machinery and Electronics, 1997 (3): 20 ~ 22