DECtape

from The Free On-line Dictionary of Computing (8 July 2008)
DECtape

   <hardware, storage> A reel of {magnetic tape} about 4 inches
   in diameter and one inch wide.  Unlike today's {macrotapes},
   microtape drivers allowed {random access} to the data, and
   therefore could be used to support {file systems} and even for
   {swapping} (this was generally done purely for {hack value},
   as they were far too slow for practical use).  DECtape was a
   variant on {LINCtape}.

   In their heyday DECtapes were used in pretty much the same
   ways one would now use a {floppy disk}: as a small, portable
   way to save and transport files and programs.

   (1995-03-16)