The vacuum system provides a physical buffer between the precision movements of the capstan and the large movements of the reels by storing a short length of tape in the vacuum column under relatively low tension. The vacuum columns are chambers open at one end, the openings being in line with the tape path before and after the capstan and roller assemblies. The amount of tape in the column is controlled by four optical or vacuum sensors on the sides of the columns. The control electronics keep the curve of the tape loop between the two inner sensors, cueing the supply reel to feed more or the take-up reel to take more as necessary. The outer two sensors, at the very top and bottom of the columns, serve to sense malfunctions in the feed mechanism during operation, prompting the control electronics to shut off all operation of the tape transport and vacuum system to prevent damaging the tape. Because of the tension provided by the vacuum columns and the design of the tape path, tape is usually kept in sufficient contact with the relatively high-friction coating on the capstan that a pinch roller is not used.