Watford 62 DFS is identical to Watford DFS except it places a second catalogue in sectors 2 and 3 of track 0, allowing 62 files on one volume. To identify the second catalogue it sets its title to 12 × &AA bytes.

Without due care a system running Acorn DFS can corrupt a Watford disc as it is unaware of the extra files. On such a system the user may run a *SWAP utility to exchange the catalogues. In practice there is a special entry in the first catalogue (directory !, name !!!!!!!, length &200, start sector 2) protecting the second one from being overwritten.

If any file in the first catalogue starts before sector 4, and it is not the special file, the disc is not a Watford DFS disc.

names, which are cleared in Acorn DFS.

Sources

This section is based loosely on the following:

• Acorn DFS disk format - beebwiki.mdfs.net
• Acorn, Watford, Solidisk and Duggan DFS Filesystem Structure mdfs.net