The MELCOM 80 Model 31, announced in 1974, was the first Mitsubishi Electric office computer to have an operating system. The Model 31 came with AOS (which stood for “All-round Operating System”), a single-task operating system. Later, Mitsubishi Electric developed DPS (“Dynamic Processing System”), a multitask version of AOS, for the Model 38, which was announced in 1977. In this way, either AOS or DPS could be selected to match the machine’s configuration. Both had 16-bit architectures. The operating systems consisted of three main components: processing programs, management programs, and system generation.