It was thought to be like that - back in the day when everything used interrupts for syscalls, hence 'system' was mentioned. (Apple II had fixed address calls,

It was thought to be like that - back in the day when everything used interrupts for syscalls, hence 'system' was mentioned. (Apple II had fixed address calls, though - no interrupts) It's quite the same as DOS being 'disk operating system' - it was able to drive the floppy and provide a file system.