CP&#x2F;M and MS-DOS weren&#x27;t really an &#x27;operating system&#x27; in the sense that they didn&#x27;t mediate application access to system resources. They didn&#x27;t let two apps share even fundamental devices like the clock, timer interrupts, networks, serial ports and on and on. In fact they didn&#x27;t support multiple apps much at all.<p>I would call both of them &#x27;monitors&#x27; or something. Operating System is way to ambitious a name for what they did.