The Dictabelt, in early years and much less commonly also called a Memobelt, was an analog audio recording medium commercially introduced by the AmericanDictaphone company in 1947. Intended for recording dictation and other speech for later transcription, it was a "write once read many" medium consisting of a 5 mil thick transparent vinyl plastic belt 3.5 inches wide and 12 inches around. The belt was loaded onto a pair of metal cylinders, put under tension, then rotated like a tank tread. It was inscribed with an audio-signal-modulated helical groove by a stylus which was slowly moved across the rotating belt. Unlike the stylus of a record cutter, the Dictabelt stylus was blunt and in recording mode it simply impressed a groove into the plastic, rather than engraving it and throwing off a thread of waste material.
Dictabelts were more convenient and provided better audio quality than the reusable wax cylinders they replaced. The belts could be folded for storage and would fit into an ordinary letter-size envelope. However, the plastic lost flexibility as it aged. If a belt was stored sharply folded for a long time, it would become permanently creased and unplayable without special treatment. Dictabelts were red until 1964, blue from 1964 to 1975, then purple until they were discontinued around 1980. Each had a capacity of about 15 minutes at the standard speed. At least one Dictaphone model featured a half-speed, low-fidelity 30 minute option.
In the 1960s, Virginia required that all of its circuit courts be outfitted with Dictabelt machines.