DECtape (orginally known as Microtape) was designed by Digital Equipment Corporation for use as a tape storage system for its PDP line of minicomputers, and was introduced in 1964.
It is a ¾ inch tape format, originally based on a similar format called LINCtape, but with it’s tape travelling in the opposite direction.
DECtape was a very reliable storage medium, and one reason was that the tape was laminated, with the magnetic layer between two layers of mylar. Another reason was that all tracks were duplicated on each half of the tape’s width.