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本文介绍一个以单板机(或微处理机)为基本模块构成多机系统的方案。为了使得系统结构简单,在性能/价格,可靠性,可维性和可扩充性方面获得好的效果,本系统采用二级总线结构。第一级为系统总线,第二级为分机总线。为增强机间通讯能力,提高信息传输率,解决由于采用总线结构所带来的总线上的数据拥挤,即所谓的瓶颈问题,本系统采用字块式DMA 传输方式来完成机间通讯。为提高系统的可靠性,第一级总线设二条,一条是主机总线,另一条是共享存贮器总线(简称共存总线)。机间字块式 DMA 传输方式的通讯就是通过主机总线进行的。除此,主机总线还配有系统中所需要的所有 I/o 设备和外有设备,为各分机提供设备共享。它还可配有远程通讯接口,以实现与远程计算机网(或设备)通讯。共存总线是为各分机共享存贮器所设置的。分机之间除可按上述(DMA)方式通讯之外,还能通过共存进行通讯。为其增加这样一种通讯方法之后,主机一旦故障,分机之间仍能保持通讯联系,使得系统可以继续运行下去。从而提高了系统的可靠性。主机和共存相当于一个宠大的“资源库”供各分机共享。
This article describes a board machine (or microprocessor) as the basic module constitutes a multi-machine system solution. In order to make the system structure is simple, get good results in performance / price, reliability, maintainability and scalability, the system uses two bus structure. The first level is the system bus, the second level is the extension bus. To enhance the ability of inter-machine communication, improve the information transmission rate, and solve the problem of data congestion on the bus caused by using the bus structure, the so-called bottleneck problem, the system uses word block DMA transmission to accomplish inter-machine communication. In order to improve the reliability of the system, there are two buses in the first level, one is the host bus and the other is the shared memory bus (referred to as the coexistence bus). Machine word block DMA communication mode is through the host bus. In addition, the host bus is equipped with all I / O devices and external devices needed in the system to provide device sharing for each extension. It can also be equipped with a remote communication interface to communicate with a remote computer network (or device). The coexistence bus is set for each extension shared memory. In addition to the extension between the above (DMA) communication, but also through the coexistence of communication. To add such a communication method, the host in the event of failure, the extension can still maintain communication between, so that the system can continue to run. Thus improving the reliability of the system. Host and coexistence is equivalent to a pet big “resource” for the sharing of all extensions.