Magnetic tape filesystem
cclist at sydex.com
Sun Feb 8 20:02:16 CST 2015
Disks and drums were a luxury on old systems; there were many versions
of tape-only operating system. Even S/360 had TOS.
Anyone know of a port of IBSYS or FMS to modern gear?
One of the problems of using tape as a working medium is that, with a
few exceptions, rewriting of data in place can be problematical. (with
tape speed variations, you aren't guaranteed that overwriting a block on
tape will occupy the same amount of tape as the old one.
So you're essentially limited to skipping to a filemark, then creating a
new end of information by writing after that.
However, many mainframe systems automatically archived inactive files to
tape, retrieving them back to disk when requested. There were tape
robots for regular 10.5" reels, as well as interesting mechanisms for
storing data on special tapes, e.g. IBM 3850, 2321.
Archive and a few other PC QIC-based systems allowed for block overwrite
and could simulate a disk, albeit pretty slowly.
And then there's the Exatron Stringy Floppy.
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