Magnetic tape filesystem

[Eric Smith]

On Sun, Feb 8, 2015 at 5:50 PM, Tom Sparks <tom_a_sparks at yahoo.com.au> wrote:
> I am wondering if there were any magnetic tape filesystem?
[by which you presumably mean true random-access tape, rather than
e.g. 9-track which is normally append-only]

Yes.  Obvious examples are DECtape/LINCtape.  Different operating
systems used different file systems, but they generally appeared to
software as a small, slow disk.

> Has anyone tried putting cp/m or fat filesystem on audio cassette?

Most instances of tape file systems I've ever dealt with used a file
system specifically designed for efficiency on tape.  For instance,
the TOPS-10 DECtape filesystem normally used every nth block for a
file, rather than consecutive blocks. This is somewhat like sector
interleave, except that it's done at the filesystem level rather than
being hidden by either hardware or a low-level block device driver.

Some members of the 6502 Group (established 1975, still meeting
weekly) developed the XPL0 programming language (similar to ALGOL and
BCPL), and an operating system partially written in XPL0, called TFS
("Tape File System") for use on homebrew or Digital Group 6502-based
systems with digital cassette drives.  TFS eventually evolved into FFS
("Floppy File System"), and then APEX, which was sold for use on the
Apple II by Apparat (better known for NewDOS/80).