Shizuo Yokohata

A module structure real-time operating system for microcomputers

With the advent of large-scale and complicated microcomputer application systems, the role of OS is becoming more important. An OS which can cope with various application requirements is strongly desired. This paper aims at the construction of OS which can be made optimum for various real-time applications. A construction of real-time modular structure OS using the microcomputer 68000 is proposed. The message-passing and procedure-call schemes are combined to connect the modules. A two-layered hierarchy module structure is proposed, suppressing the increase of the overhead due to modular implementation, and also providing the flexibility for replacing modules. By this scheme, operating systems with capacity from 10 KB to 150 KB can be constructed, covering a wide range of applications from a small-scale system with hardware built-in structure to the relatively large-scale system requiring programming functions, by simply modifying the combination of modules. To utilize commercial softwares or general-purpose OS in the real-time environment, a scheme is proposed in which the general-purpose OS is executed as the secondary OS with the real-time kernel. As a result of evaluation, when a general-purpose OS, CP/M-68K, is executed as the secondary OS, the processing time is increased by 12.7% compared with CP/M-68K directly implemented on the 68000.

Organization of a real-time operating system “A-RMS”

As technologies in the process control and the equipment control fields become more and more advanced, there are increasing needs for a real time operating system which provides the interactive processing function in addition to the conventional control function. In the past, as a means to cope with these needs, technologies such as the virtual machine system of the emulation system were proposed. However, these systems presented difficulties in handling because each environment in these conventional systems uses its own operating system interface. This paper describes “A-RMS,” a newly developed real-time operating system which incorporates an interactive processing function as native on top of a real-time operating system providing a control function. The control function and the interactive processing function are realized with unified concept and specification in A-RMS. Adverse effects on the control function which might be induced by the incorporated interactive processing function are prevented by introducing a concept of environment to separate the interactive processing function from the control function. The new operating system is implemented on the M68010. This paper also mentions the effect of incorporation of the interactive processing function on A-RMS performance. To secure response, A-RMS employs only the real memory. The memory management unit (MMU) is used exclusively for memory protection.