Disc Filing System

The Disk Filing System (DFS) is a computer filing system developed by Acorn Computers Ltd.

The original DFS was a ROM for the BBC Micro. It has an extremely limited design in order to make best use of the 100k floppy discs it was originally designed for. It uses a flat directory structure with one letter to represent the current directory ($ by default). Changing directory meant using a different letter as the prefix. You could refer to a file in a different directory by prefixing it with the letter and a dot, eg "A.LETTER". Names could be up to 7 letters long, plus one letter for the directory. The file table was one disc sector, limiting the number of files on the disc to 31.