Abstract: A slave device detecting system utilizes the past history of devices connected to a data bus to optimize the time required to re-establish communications. Whenever a master controller senses a condition that requires an assessment of devices on the bus, it examines the addresses of previously connected devices at more frequent time intervals than it does for addresses that were not previously associated with connected devices. In a preferred approach, all valid addresses can be examined in a sequential fashion, and the address of the previously connected device can be examined at every fifth or tenth position in the sequence. With such a technique, a device will be detected much faster once it has returned to the bus.

Abstract: Apparatus and method for detecting a sync signal in parallel data which has been reconstituted from serial data. The first occurrence of digital bits which corresponds to a predefined sync signal is recognized and causes the circuitry to shift to a mode of operation in which subsequent sync signals will be recognized if and only if they occur within a predetermined "window" around the expected position of the sync signal. The sync signal is used re-align the parallel data so that the bits are grouped into meaningful words.

Abstract: A new automatic tracking method is disclosed for the accurate positioning of a magnetic head with information previously recorded on the magnetic tape. If a moveable magnetic head is used, the position thereof is first normalized. Thereafter tracking is automatically adjusted based on a repetitive sampling process in which the results are mathematically averaged to determine a precise center position. Finally, new video material is physically positioned on the magnetic track according to a single offset error measurement and this offset error is stored and used in all subsequent edit operations.

Abstract: A new automatic tracking method is disclosed for the accurate positioning of a magnetic head with information previously recorded on the magnetic tape. If a moveable magnetic head is used, the position thereof is first normalized. Thereafter tracking is automatically adjusted based on a repetitive sampling process in which the results are mathematically averaged to determine a precise center position. Finally, new video material is physically positioned on the magnetic track according to a single offset error measurement and this single offset error is stored and used in all subsequent edit operations.

Abstract: An improved reel servo for a recording and reproducing machine is disclosed. The reel servo as well as other servos in the machine are controlled by a single microprocessor which results in greater inherent communication between such servos and significantly improved operating capabilities. The reel servo itself is adapted to have the supply and take-up reels operate in different kinds of close loop servo control during various operating modes. The servo circuitry provides instantaneous information to the microprocessor for determining the diameter of tape that is wrapped on each of the reels. The reel servo has the capability of performing high speed shuttle and cueing operations without engaging the capstan and the tensioning arm can be positioned to provide the appropriate tape tension during shuttling in both the forward and reverse directions. An acceleration loop controls the supply reel so that the tape tension is maintained within predetermined upper and lower limits.