Simplest (practical) file system?

Bob, pre-CP/M, the fairly popular North Star DOS filesystem simply used a directory (first four blocks of the filesystem) with the name, starting sector, number of sectors, and type for each file (16 bytes per entry). Each file was laid out contiguously on the disk, starting at the sector indicated and continuing for the set number of sectors. There was no file allocation table or similar structure. It's lightweight and simple, but it required you to know or "guess" the length of a new file when creating it. You could specify a starting sector when creating a file, but if you didn't, N*DOS would traverse the active directory entries to find the highest-numbered used sector (start+length of each active file), then create the new file at highest+1. And "growing" a file was a leap of faith--if there was free space after it (and you had to know), you could delete the file, which modified only the directory (didn't touch the data blocks), and immediately recreate it with a new increased length using the same starting sector. You could, of course, shrink a file using the same process. An included utility would compress "holes" out of the filesystem caused by deleted or shrinking files. --Patrick