Abstract: A tape drive includes a rotary head assembly for recording and playing back a series of arcuate tracks on a moving tape where the tracks are transverse to the longitudinal axis of the tape. The tape drive includes a servo mechanism for correcting track misregistration by adjusting the position of the rotary head assembly with respect to the tape in response to servo information in the arcuate tracks. A close transducing engagement between the tape and the rotary head assembly is provided by creation of a low ambient pressure between the assembly and the tape when the assembly rotates.

Abstract: A system for receiving data which is destined for station facilities on a ring-topology network includes a forwarding data channel for establishing data communication between the ring-topology network and the facilities. A station memory for selectively holding data to be transmitted from the facilities over the forwarding data channel and onto the network is also connected to the channel. Additionally, a processor, which generates and continually updates an instruction data frame with address information about the facilities is connected to the station memory. A switch interconnects the forwarding data channel with the ring-topology network to selectively receive data onto the station's channel from the network. A content addressable memory (CAM), which is also connected with the forwarding data channel, receives instruction data frames from the processor, via the station memory over the channel, to control the switch in accordance with address information contained in the instruction data frame.

Abstract: This system moves magnetic tape past the read/write head at a constant velocity by separately servo controlling the source reel motor and the take-up reel motor. Separate fine encoders are associated with each reel, each encoder providing multiple pulses for each revolution of the respective reel. Two radius calculation circuits each receive pulses from a respective one of the encoders and each calculate therefrom the radius values of tape on both of the reels. A radius information selector then selects, for use in controlling the motors, that set of radius values which is calculated by the calculation circuit which is receiving encoder pulses at the greater sampling rate. Separate servo circuits drive the two motors at respective angular velocities determined by utilizing the selected set of radius values. In each drive circuit, the associated tape radius is multiplied by the actual reel angular velocity, as indicated by the time duration between consecutive pulses from the encoder associated with that reel.