我们在研制MTC微计算机控制器过程中,对TRS-80 Model Ⅲ微计算机系统内部总线和IO扩展口进行了分析,TRS-80不能实现DMA传送,故作了必要的改进。通过改进后,不仅保持了原系统的功能,而且使其系统内部总线控制和IO扩展口具有使用的灵活性和通用性,扩展口既可作为扩展外设使用,也可进行DMA方式传送;使系统功能有所加强。改进后主机稳定可靠,DMA方式运行正常。 TRS-80 M0delⅢ微计算机系统,系采用Z-80作CPU,提供有ROM 16K,RAM32K,可扩展到48K(我们已扩展),配有5吋软盘及软盘驱动器两个,可扩展到四个,设计有RS-232串行接口,盒式录音机接口以及IO总线扩展口,CRT与主机在一起,外围配有打印 In the process of developing MTC microcomputer controller, we analyzed the internal bus and IO expansion port of TRS-80 Model III microcomputer system, and TRS-80 can not realize DMA transfer, so we made the necessary improvement. Through the improvement, not only maintain the original system functions, but also to make its system internal bus control and IO expansion port has the flexibility and versatility to use, expansion port can be used as an expansion of peripherals, but also can be DMA transfer; make System functions have been strengthened. Improved host stable and reliable, DMA mode is operating normally. The TRS-80 M0delIII microcomputer system uses the Z-80 as the CPU and is available in ROM 16K, RAM 32K, expandable to 48K (we have expanded it) with two 5 "floppy and floppy drives expandable to four, Design with RS-232 serial interface, cassette recorder interface and IO bus expansion port, CRT and the host together, the periphery with a print