Magnetic tape filesystem

On Sun, Feb 8, 2015 at 5:50 PM, Tom Sparks <tom_a_sparks at yahoo.com.au> wrote: [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. 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).