In this thesis, we designed and implemented a microkernel for KAICUBE860, the massively parallel system for scientific calculation. Three basic requirements arise in such an operating system design : extensibility, efficiency and reconfigurability. Extensible operating system can keep pace with hardware advances and user demands. One of the most important requirements for the massively parallel system is performance. The operating system should be efficient enough to provide the maximum performance of the system. And the system can be reconfigured dependent on the functional requirements of users. For theses three requirements, we employed the program family concept. A kernel family is constructed in user-driven fashion from a minimal single-user/single-tasking kernel to a full functional multi-user/multi-tasking kernel. Then the most appropriate kernel is selected for user task. To implement a kernel family object-oriented approach is used. All kernel codes were written in C++ and i860 assembly language.