Back in the olden days when DOS was a mainframe operating system, competing with it's big brother "OS/360" there was a cartoon floating around that summed it up. OS was represented as a fat giant in a loincloth with a big ugly club and DOS was a small muscular guy in a superman suit.
In 1964 DOS was a true multitasking OS that ran in 16k of storage with up to 3 partitions of applications running concurrently.
Microsoft didn't get that going until W/95
