I have seen base32, base36 and base96 used to pack file names and other information into directories on disk storage media. This was particularly popular in the early days of floppy disks where storage space was rather limited. Base 96 is interesting because it permits all of the "printable" ascii characters to be encoded into 7 bits such that 8 characters can be mapped to 7 bytes (56 bits) of storage. In a system such as this the remaining code positions from 96-127 in the 7 bits can be used for a limited number of control codes and escapement characters.

One project I worked on a while back was to rig up an 8 inch floppy drive so it could interface to a IBM PC computer running MSDOS. My client had a depot level test rack for certain avionics gear that contained a core functional testing module made by Genrad that used an ancient file system on 8 inch floppy disks to store test scripts and programs. The client wanted a method in their documentation control center to be able to archive 1000's of 8 inch test disk file sets onto their corporate network server. The 8 inch drives I setup for them were to have the capability to read files off the 8 inch disks for storage and the ability to re-create new disks on demand from the archival storage. I wrote a file system translator for the PC that hosted 8 inch drive connections so that the Genrad 8 inch disk files could be translated to and from the MSDOS network environment.

When reverse engineering the Genrad file storage system from the 8 inch disks I found that they used a base32 encoding for the file names on the disk. This encoding uses a 5 bit code for each file name character and as such it was possible to store three file name characters into each two bytes of directory entry in the diskette. The file names were limited to using the characters ABCDEFGHIJKLMNOPQRSTUVWXYZ*-<>$.

Now while that work was done back in about 1986 it would be interesting to see if it was even feasible to try a project like that for connecting an 8 inch disk up to a Windows machine!!! I still have a drive and the MicroSolutions CompatiCard ISA disk controller board that was used.!!

Michael Karas