Abstract: A helical type tape recording and reproducing system records blocks of user data of predetermined size by reformatting the user data blocks into physical blocks that are recorded on tape, with the physical blocks being recorded as double frames. Each double frame is recorded on a set of successive helical tracks, preferably 32 tracks. Each double frame has system format data interleaved with the user data block data which identifies the double frame as being of a particular type. The present invention is directed to the types of double frames that are used to begin a recording, particularly an append recording which involves recording by the system at a previously recorded tape which may have been recorded by a different system, as well as the types of double frame that are used to end a recording.

Abstract: An apparatus for an axially displaced flexural bearing support assembly including a unitary or monolithic bearing support base member having a bearing receiving tube supported by a first and second generally parallel arrangement of flexural spoke members to control bearing pre-load due to axial differential expansion while eliminating radial displacement of the spindle or shaft supported within the tube. The spoke members of each arrangement include a plurality of spoke members arranged in parallel planes generally perpendicular to the axis of a spindle insertable within and supported within the tube by means of bearings. In the preferred embodiment, there are three spokes for each set in each plane, with the spokes being equiangularly displaced.

Abstract: A system for recording and reproducing data including user data on a magnetic tape having a number of partitions in which recording can be performed, the tape having at least one system zone in which user data is not recorded, the system having a table of data located near the beginning of the tape and near each system zone with the table including data identifying the physical location of the system zones and partitions and other sections of the tape.

Abstract: Input data symbols are written in a write buffer then to a sync adder, which appends a pseudo randomly (PN) generated sync bit to the MSB position of a four-symbol sync word data field, to generate a sync word. Sync words may or may not be randomized and sent to a receiver whereafter synchronization is recovered and perhaps de-randomized symbols are written into particular positions of an ECC block in a read buffer which are derivable from the PN sequence. The ECC block is a data array having multi-bit sync words making up its rows and the bit positions of the sync words making up its columns. Synchronization recovery apparatus conceptually looks at each bit position across a row and in a top-to-bottom direction down each of the columns to locate that column which contains the appended PN sequence. Sync recovery involves the receiver re-generating the same PN sequence that was generated at the transmitter.

Abstract: A method and apparatus for input data clock presence detection which utilizes an up/down counter clocked by a reference clock, which operates at a nominal frequency rate half of the nominal rate of the input data clock, and an R/S flip-flop causing the up/down counter to count up when set, and to count down when reset. The R/S flip-flop is cleared by the reference clock and set by the input data clock. The counter is selected to count up to its maximum number and remain there when continuously clocked up. Similarly, when continuously clocked down, the counter reaches its minimum number (zero) and remains there. So long as the input data clock is present and has the correct rate, after each reference clock pulse resets the flip-flop and prepares the counter to count down, there is at least one input data clock that sets the flip-flop and prepares the counter to count up.

Abstract: A helical tape recording and reproducing system which has longitudinal physical address track for recording physical address data relating to the physical layout of the tape and a logical address track that contains data relating to the content of the recorded helical tracks. Each address track has recorded segments with each of said segments containing data corresponding to a particular pair of helical tracks recorded in said helical recording area. Each segment has a multiple bit front field of a first predetermined timing synchronization bit pattern, a first predefined synchronizing word, a multiple bit segment information field of data, a second predefined synchronizing word and a multiple bit rear field of a second predetermined timing synchronization bit pattern.

Abstract: A recording and reproducing system records blocks of user data of predetermined size by reformatting the user data blocks into physical blocks that are recorded on tape. Each physical block is recorded as a double frame on a set of successive helical tracks, preferably 32 tracks. The system has the capability of verifying whether a physical block has been accurately recorded, and if not, the system automatically rewrites the physical block downstream without stopping or repositioning the tape. If an accuracy verification confirmation does not occur until a next physical block is being recorded, the system demarks or invalidates that physical block being written, and rewrites both the failed physical block and that following physical block downstream of that physical block being written.

Abstract: Editing of information recovered from a relatively high speed communications medium such as a communications channel or magnetic tape often times allows only a portion of the information to be recovered. Storing information in complete segments from which portions of an image, called "snatches," may be recovered helps. An image signal is compressed in such a way that a snatch can be used during decompression to reconstruct a recognizable image from less than all the information that defines the image-thereby giving rise to the notion of a partially reconstructed image. The image information comprises several pixel data blocks with each block including sufficient pixel image data to reconstruct a portion of the image. The pixel data blocks are discrete cosine transformed ("dct") to generate a set of dct coefficient blocks.

Abstract: A tape data recording and reproducing system is disclosed which has an over-writing capability which can result in previously recorded data continuing to exist on the tape after the over-writing has been completed. The present invention uses cyclical redundancy check data that is normally recorded with the data to determine if the data recovered during reproducing is valid data.

Abstract: An audio receiver FIFO memory buffer in the serial digital video interface allows improved timing synchronization between video and audio information. Furthermore, it eliminates unpleasant sound effects when multiple data samples are skipped or repeated in series. This FIFO receiver buffer receives data at an input write-data rate filling up the memory storage cells therein. An output read-data signal clocks the data out of the memory storage cells. The FIFO's fullness is monitored and maintained, in response to an external signal, to within a specified range delimited by an upper and a lower threshold. If the FIFO buffer fullness is below the range's lower threshold, then the FIFO's read address pointer is held so that the immediately preceding read out data element is read out again, but only once. On the other hand, the FIFO buffer fullness is over the range's upper limit, then the FIFO's write address pointer is held so that the immediately preceding written in data element is written over, but only once.

Abstract: A tape recording and reproducing system records blocks of user data of predetermined size by reformatting the user data blocks into physical blocks that are recorded on tape. Each physical block is recorded as a double frame on a set of successive helical tracks, preferably 32 tracks. The system has the capability of verifying whether a physical block has been accurately recorded, and if not, the system rewrites the physical block downstream without stopping or repositioning the tape. If an accuracy verification confirmation does not occur until a next physical block is being recorded, the system demarks or invalidates that physical block being written, and rewrites both the failed physical block and that following physical block downstream of that physical block being written.

Abstract: A method for analyzing the relative spatial alignment of the erase head pole tips relative to the record head pole tips on a recording of a magnetic tape to be partially overwritten by providing, through first and second erase heads, successive momentary erase pulses of a predetermined time duration in a predetermined phase relation on a non-overlapping basis, wherein each erase head thereby erases recorded information while leaving portions of information therebetween on adjacent track pairs, and then reading or playing back the results of the erasure for analysis of the RF envelope of the erasing pattern by a waveform monitor or ferrofluidic techniques. The duration of the erasures and playback is such that the RF envelope includes at least one erasure from the first erase head and at least one erasure from the second erase head.

Abstract: A magnetic transducer for reproducing/recording high frequency signals with a magnetic tape medium includes a pair of opposed transducer head halves separated by an insulation gap and bonded together to form a Y-shaped pole structure, each half including a laminated at least partially ferromagnetic core portion bounded on opposite surfaces with conductive layers, each of which forms a winding coil portion. Each core section is formed as one-half of a Y-shaped cross-sectional configuration having a leg portion and an angularly disposed arm portion, the distal end of which is capped with a block-shaped ferromagnetic pole tip in magnetic path relation therewith, the two pole tips lying in a common plane transverse to the plane of the gap. The conductive layers on the outer and inner surfaces of the laminated core section form outer and inner conductors which, when conductively interconnected, such as by jumpers, are configured to form a one or two turn coil for the transducer.

Abstract: An enclosure latch arrangement including at least one latch assembly for securing a first enclosure portion relative to a second enclosure portion by providing, on the inside of the first enclosure a stationary latch bracket member having a pair of spaced pin members on a common line. The second enclosure portion is provided with at least one latch bar assembly, which includes a spring biased latch actuator in slidable abutting relation with a latch bar secured within the enclosure. The latch actuator is barshaped and has a pair of spaced pawl openings formed in an edge thereof, spaced a distance equal to the spacing between the pin members, with the pawls including cam edges at the point of operative coaction with the pin members.

Abstract: An apparatus for controlling conditions in response to an operator input, the apparatus including a rotary knob coupled to the shaft of the rotor of a stepper motor having first and second stator windings, in quadrature, with each winding being center tap grounded to provide first and second winding portions for each winding. One pair of first winding portions are used for providing pulse inputs to a microprocessor on rotation of the knob, in either direction, via a pulse control system, with the microprocessor providing command signals to a braking control system, which includes a direct current power control source, which may be either a voltage or current control source. The power control source, in turn is in circuit relation with the pair of second winding portions.

Abstract: An ultra small track width magnetic transducer and manufacturing method. The transducer has two coplanar confronting magnetic poles provided by a thin film layer of magnetic material. The thickness of the layer defines a track width. A transducing gap is etched in the magnetic layer by utilizing focused ion beam milling technology. The thusly obtained gap has a predetermined length and depth and it separates the magnetic layer into two confronting coplanar magnetic poles. A layer of non-magnetic material is deposited over the magnetic layer to fill the transducing gap. The transducing gap may be etched in a plane extending orthogonally to the plane of the magnetic core layer. Alternatively, the transducing gap plane may extend at an oblique angle to the magnetic core layer to obtain a transducing gap useful in aximuth recording/playback. A window in the magnetic layer interconnects conductor leads to form a transducer winding.

Abstract: A technique for establishing and maintaining full duplex communication between two stations connected to a token ring network, without physically reconfiguring the station connections or otherwise disturbing the network. In an auto-configuration full duplex mode of operation, each station ascertains whether there are only two active stations on the network and, if so, performs an exchange of frames with the other station to establish full duplex communication. One way to ascertain whether only two stations are active is for each station to transmit periodically a neighbor information frame, which contains the indentities of the source station and the source station's nearest upstream neighbor. Once established, full duplex communication can proceed at a greater bandwidth than communication in a token ring network, and without latency delays and distance limitations associated with token ring networks.

Abstract: An electrically isolated high speed optical switching arrangement for use as a computer over-voltage sensing circuit utilizing first and second optoisolator devices, the first having an input, a first signal from the output of a bus sensing circuitry which provides two complementary outputs, with the output voltage of the optoisolator controlling power-down circuitry for the computer in response to an over-voltage condition. A second control optoisolator has its output in parallel with a resistor in the base to emitter path of the first optoisolator. The complementary signal of the bus-sensing circuitry provides the input to the second optoisolator. During normal power conditions, the first optoisolator is conductive and the second is non-conductive.

Abstract: A method for selective disclosure of the identity of a communication protocol under which an information packet originated, but without incorrectly identifying the protocol in a header accompanying the packet. If there is a need to conceal the identity of the underlying source protocol, a special anonymous protocol identifier is used, instead of the real protocol identifier, in the header of an encrypted information packet. Network monitors can then still provide accurate information concerning traffic on the network, without having this information distorted by the use of incorrect communication protocols. If there is a desire to reveal the underlying protocol, a subnetwork protocol frame format is used to store the protocol identity and signify whether the packet is encrypted. A packet that is of a non-subnetwork protocol can be encapsulated with a subnetwork header containing a special code signifying that there is an encapsulated packet and containing the original protocol identifier.

Abstract: A method and related cryptographic processing apparatus for handling information packets that are to be cryptographically processed prior to transmission onto a communication network, or that are to be locally cryptographically processed and looped back to a node processor. A special cryptographic preamble is included in each information packet that is to be subject to cryptographic processing. The cryptographic preamble contains an offset value pointing to the starting location of information that is to be processed, and completely defines the type of cryptographic processing to be performed. The cryptographic processor can then perform the processing as specified in the preamble without regard to a specific protocol. If the packet is to be transmitted onto the network, the preamble is stripped from the packet after cryptographic processing, so that the formats of packets transmitted onto the network will be unaffected by the preamble.