Physically speaking, how do you tell the difference between a DECTape drive and a LINCtape drive? -- By the time PDP12's were built, DEC was using the same transport (TU55's, later TU56's) for either format. LINCtapes are loaded on the right-hand reel, and forward tape motion is counter-clockwise. DECtapes are loaded on the left-hand reel and forward tape motion is clockwise. The only other gotcha is the timing track is the opposite polarity between the two formats.