On Sun, Jul 17, 2016 at 10:41 AM, Al Kossow <aek at bitsavers.org> wrote: You might be confusing Hypertape (7340 drive) with the "Tractor" robotic tape cartridge system (7955), which was designed for the NSA Harvest system (7950).* I don't think Hypertape was ever used on Stretch or Harvest. Tractor used 1.75 inch tape. Only one Tractor system was built, and was used from 1962 to 1976 by the NSA. Hypertape cartridges were physically smaller than Tractor cartridges. Hypertape used 1 inch tape with phase encoding, at a tape speed of 112.5 inches per second for data transfer and 225 ips for rewind. The original transfer rate was 170,000 characters per second. The 7340 Model 1 drive was used on the 7074 and other 70xx systems with the 7640 control unit. The first customer for the 7340 Model 1 was the National Revenue Service of Canada. The 7340 Model 3 drive doubled the recording denisty and transfer rate, and was used on 360 systems with the 2802 control unit. There were only two 7340 Model 3 installations outside IBM, at the Internal Revenue Service and Boeing. Source for Hypertape information: _IBM's 360 and Early 370 Systems_, by Emerson W. Pugh, Lyle R. Johnson, and John H. Palmer * The 7950 Harvest system was a 7030 Stretch system with the addition of the 7951 stream processing unit, 7952 high-performance core memory, 7955 Tractor tape system, and 7959 high-speed exchange.