Sony Betamax J-5 J-7

Sony’s Betamax is the 12.7 mm (0.5 inch) home videocassette tape recording format introduced in 1975 and derived from the earlier, professional 19.1 mm (0.75 inch) U-matic video cassette format. Like the video home recording system VHS introduced by JVC in 1976, it had no guard band, and used azimuth recording to reduce cross-talk. The “Betamax” name came from the fact that when the tape ran through the transport it looked like the Greek letter “Beta”.