Design concept and implementation of mu ITRON specification for the H8/500 series

A description is given of HI8, a compact operating system (OS) based on the mu ITRON specification that has been developed for the H8/500 series of single-chip microcomputers. HI8 fully implements level three of the mu ITRON specification. Concerning two critical parameters of real-time operation, HI8 has been confirmed to have a maximum interrupt-masked time of 15.0 mu s and maximum task dispatching time of 24.0 mu s. The OS object code has been compressed to a size of 1.9 kb to 4.7 kb, leaving ample space for application programs to operate in the on-chip ROM (32 kb) and RAM (1 kb) of the H8/532. It is anticipated that real-time operating systems conforming to the mu ITRON specification will come into use in the single-chip application field. Current plans call for HI8 to be expanded to support levels four and five of the mu ITRON specification.<
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