DECtape was introduced in 1963 by Digital Equipment Corporation,
and was used on many of their PDP series computers, from the
PDP-6 to the PDP-15. The tape was 3/4" wide, with a 3-7/8"
diameter reel, and was formatted into blocks. A tape could
hold 184K 12-bit words, or 144K 18-bit words. Date was written
redundantly across the tape, so data reliability was high.