It would seem to logically follow that a Disk Operating System would have a directory list utility for disks like ‘dir’. It was there in the first version called 86 DOS.

https://en.m.wikipedia.org/wiki/86-DOS

`dir` was also in CP/M. Though it didn't have a concept of a file hierarchy, so it listed all files on the disk (but did support supplying a pattern to filter against).