MOSI - Microprocessor Operating Systems Interfaces - applies to program interfaces for microprocessor operating systems. The goal of the standard is to facilitate the writing of portable application programs or systems. Using this standard, a programmer should be able to write programs that with few, or no, changes at the source level, may be run on many different computer systems, that is particular machines running particular operating systems. This standard designates the capabilities required by various microprocessor-based applications. The process of transporting a given application to a new environment consists of obtaining a copy of the source program, modifying it if necessary, processing it with a translator that targets the desired system, and executing the code produced by the translator. If no change to the source is required, there may be perfect portability. Minor changes to the source are usually an acceptable compromise. This specification is designed to enhance this portability. Three components: the language, the operating system, and the machine architecture are all predetermined and highly variable. MOSI makes no attempt to standardize or constrain the structure of any of these. However, the standard provides the application programmer with a dependable mechanism to be used to communicate within a chosen language with the operating system. It is the responsibility of a conforming operating system or language translator to provide the appropriate interfaces as specified in this standard.