Ampex Corporation

Hewlett-packard Development Company, L.P.

Richard K Brush

Michael John Erickson

John P Watney

An apparatus and method for indicating and allowing hot swapping of a circuit board. During both insertion and extraction of a circuit board from a system, two inputs signals are generated from staggered pins located on the circuit board's connector. The inputs are processed through a NAND function implemented with transistors and output to two Schmitt trigger inverters connected in series. The output of the series connection of Schmitt trigger inverters goes high when both input signals are high and goes low when one of the inputs signals goes low. In addition, through the use of a resistor, capacitor combination connected to the input of the first Schmitt trigger inverter, the output signal remains high for a period of time after one of the input signals goes low. This additional period of time prevents any damage or disruption of signaling caused by transient current and voltage fluctuations as a circuit board is inserted or extracted. The output signal can be used in both single-ended and differential SCSI applications.

Apparatus for safe installation and removal of a circuit board for hot swap applications

State activated one shot with extended pulse timing for hot-swap applications

A method and apparatus for the generation of a signal flag in response to illegal channel code patterns from an information channel, the signal flag may typically be used as an erasure flag by a subsequent error correction decoder. This erasure flag, being indicative of a data error position which can then be fed into a utilization circuit such as an error correction logic for performance improvement. In particular, a Miller-squared channel code format decoder in accordance with the present invention can easily and inexpensively provide error position information thereby enhancing error correction power, such as that of a Reed-Solomon error correction code.

Miller-squared decoder with erasure flag output

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.

Apparatus and method for sync detection in digital data

A system to improve image quality during shuttling of a video tape in a record and playback machine of the type in which each image field is recorded on one or more tracks on video tape. The system includes an offset signal source coupled to a displaceable mechanism during shuttling to provide relative displacement between a reproduce transducer and a video tape to cause the transducer to cross tracks of recorded information irregularly, thereby providing frequent updating of substantially all regions of an image field by information stored on the tape.

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Los Altos, CA, United States of America

Richard K Brush