Abstract: An electrical connector having a female contact that enables detection of the presence of a corresponding male contact. The female contact is divided into two parts. The two parts are electrically isolated. When a male pin is installed in the female contact, the male pin electrically connects the two parts of the female contact together. In a specific application, the female contact is in a connector for an external device on a SCSI computer bus. The first part is pulled high and serves as a sense line. The second part is pulled to ground. A pin in the mating connector electrically connects the two parts of the female contact, pulling the sense line to ground. The external device disables internal termination of the SCSI bus when the sense line is pulled low. In an alternative embodiment, the external device has two SCSI connectors, each with a two-part female contact.

Abstract: A tape guide for a digital tape mini-cartridge providing decreased tape wander in a direction transverse to the intended path. The guide provides an increased area of tape having increased transverse stiffness without interfering with an adjacent drive wheel. In one embodiment, the guide is cylindrical and has a cylindrical cut-out to provide clearance for an adjacent cylindrical drive wheel. Preferably, the guide has top and bottom flanges. If a top flange of the guide is present, the cut-out continues through the top flange of the guide. The top flange of the guide may be relatively thin to fit below a top flange of the adjacent drive wheel. Alternatively, the top flange of the guide may have a larger cut-out to avoid interference with the top flange.

Abstract: A magnetic tape drive having a motor with a magnetically shielded cavity or hole in one cover of the motor providing additional room for movement of a magnetic head. The cavity eliminates a mechanical interference problem, enabling direct drive of a roller (puck) combined with short overall drive height. In motors having an internal stator, some of the stator poles are eliminated and a magnetically shielded cavity is provided in the area where the stator poles are eliminated. In motors having an external stator, no stator modification is required and a shielded cavity provides access into an open area of the rotor. In addition, for motors having an external stator and sufficient magnetic shielding, a simple hole in one cover of the motor may be sufficient rather than a magnetically shielded cavity.

Abstract: A circuit and method for iterative generation of the variables used in vector generation and linear interpolation. Most significant bits are added in a last pipeline stage. Less significant bits are added in earlier pipeline stages. Breaking addition into multiple parts with each part having fewer bits to add enables a faster iterative cycle rate compared to a single long adder. Part of the vector generation algorithm requires a decision step based on the sign of the complete addition. Since this sign is generated in the last stage of the pipeline, it is not available at the time needed by earlier stages of the pipeline. Therefore, all possible combinations of outcomes for earlier pipeline stages are simultaneously speculatively computed for use by following pipeline stages.

Abstract: A position sensor for providing an electronic output indicating the magnitude of transverse movement of an edge of a magnetic tape. A first light pipe and lens arrangement is used to deliver light to one side of a tape. A second light pipe with a small light receiving aperture is used to receive light and to deliver the received light to a detector. The focal point for the lens in the first light pipe is at the receiving aperture of the second light pipe, enabling the aperture to be very small but still receive substantially all the transmitted light. The light pipe arrangement enables use of a variety of light sources and light detectors without having to place either a source or a detector physically close to the tape or the magnetic head.

Abstract: A method of inhibiting copying of digital data. In a first embodiment, a sequence of symbols is added to original data, the sequence of symbols selected to encode into channel bits having a large accumulated digital sum variance. The sequence of symbols is then encoded by a special encoder that generates special channel bits that don't have a large accumulated digital sum variance. The special channel bits may be unambiguously decoded, but the resulting decoded symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a second embodiment, a single symbol in the sequence of symbols is replaced after error correction symbols have been added. The sequence of symbols with one substituted symbol is encoded into channel bits that don't have a large accumulated digital sum variance.

Abstract: A drive chassis for magnetic tapes, the chassis having adjustable azimuth for a magnetic head. The magnetic head is mounted onto a plate. The plate has one end forming a hinge surface. The hinge surface is forced into contact with a stationary hinge surface on the chassis. A second end of the plate is moveable, permitting the plate to rotate around the hinge surfaces, thereby rotating the magnetic head. A spring in contact with the second end of the plate forces the hinge surface of the plate against the hinge surface on the chassis. In a preferred embodiment, the spring is integral with a side wall of the chassis.

Abstract: A picker for a computer information storage library. The computer information storage library includes at least one computer information drive, storage locations for data cartridges, a picker and a transport mechanism. The picker includes a sleeve for holding a cartridge and a moveable thumb. The transport mechanism provides displacement in two orthogonal dimensions for the picker. The moveable thumb provides displacement in a third dimension orthogonal to the movement of the transport mechanism. Data cartridges include two openings in a bottom surface. The thumb includes fixed fingers with bent tips that engage the openings in the bottom surface of the data cartridges. Data cartridges are removed from a drive or storage by hooking the tips of the fingers into the data cartridge openings, and then moving the thumb relative to the sleeve to pull the cartridge into the sleeve. The picker also includes a rigid thumb for pushing a data cartridge out of the sleeve and into a drive or into a storage location.

Abstract: A method for reducing power supply current surges and power supply voltage noise in an electric motor control system. The method limits the rate of change of power to the motor. The rate of change of power is limited by microprocessor firmware. Use of firmware reduces the size and weight requirements of motor control hardware and power supply filtering hardware.

Abstract: A color filter system for an optical system, applicable to optical systems in color image scanners, copiers, video cameras and digital cameras. The optical system includes a photosensor army, transmissive color filters on the photosensor array and a corrective reflective filter adjacent to the photosensor array. The transmissive color filters on the photosensor array are imperfect, transmitting too much visible red as well as infrared. The adjacent reflective filter compensates by suppressing longer visible red wavelengths and infrared wavelengths. The combination provides color precision with cost and manufacturing advantages relative to attempting to provide precise transmissive filters on the photosensor array or relative to providing compensation filters elsewhere in the system.

Abstract: A method of detecting fractional channels in a telecommunications circuit. A non-idle data rate is measured for each channel in the telecommunications circuit. Channels having matching non-idle data rates are grouped into sets. Non-idle data rates are measured again for the channels within each set. In each set, any channels having non-matching non-idle data rates (with a small predetermined range of permissible variability) are eliminated. The measurement for each set is repeated multiple times. Each remaining set has channels that have substantially identical non-idle data rates over multiple time periods and each remaining set is assumed to constitute a fractional channel. Non-idle data rates are measured by counting non-idle octets over a fixed period of time, or by measuring throughput (non-idle octets per second) or by measuring utilization (throughput/capacity).

Abstract: A tape guide for a digital tape mini-cartridge providing decreased tape wander in a direction transverse to the intended path. The guide provides an increased area of tape having increased transverse stiffness without interfering with an adjacent drive wheel. In one embodiment, the guide is cylindrical and has a cylindrical cut-out to provide clearance for an adjacent cylindrical drive wheel. Preferably, the guide has top and bottom flanges. If a top flange of the guide is present, the cut-out continues through the top flange of the guide. The top flange of the guide may be relatively thin to fit below a top flange of the adjacent drive wheel. Alternatively, the top flange of the guide may have a larger cut-out to avoid interference with the top flange.

Abstract: A control system for a cooling fan in an electronic system. Power consumption (and therefore heat) is sensed by sensing power supply current. When power supply current exceeds a threshold value, the cooling fan is turned ON. In a specific embodiment, a small (low-resistance) series resistor is placed in the regulated output path of a power supply. Power supply current is measured by measuring the voltage drop across the resistor.

Abstract: An alignment and latching apparatus for a drive mechanism for data tape mini-cartridges. The alignment and latching apparatus enables the drive to use a new mini-cartridge while retaining backward compatibility with older smaller mini-cartridges. The mini-cartridges have a plastic top cover and a rigid metal baseplate. For some embodiments, an alignment datum is defined by three reference points on the bottom of the mini-cartridge baseplate. In other embodiments, the alignment datum is split with two reference points on the top of the baseplate and one reference point on bottom of the baseplate. Alignment and latching forces are applied on both the plastic cover and onto the baseplate. In some embodiments, alignment force on the top cover is provided by flat springs. In alternative embodiments, alignment force on the top cover is provided by spring loaded rollers.

Abstract: A system and method for quiescent current testing of dynamic logic circuitry. Nodes shorted to ground are detected during a dynamic pre-charge state. Nodes shorted to a power supply potential are detected by driving all nodes of interest to ground during a dynamic evaluation phase. Nodes of interest are driven to ground directly by one additional transistor per node or indirectly by logical propagation from upstream nodes. As a result, only two current measurements are needed for all shorted node faults, even for pipelined systems with multiple clocks. There is no need for input test signal sequences and no need for signal propagation to outputs for detection. Specific embodiments are provided for single-rail logic, single-rail pipelined systems, dual-rail logic and dual-rail pipelined systems. For single-rail pipelined systems, optional transistors between stages enable preservation of logical states during testing.

Abstract: A method for removing precompensation in a Write Data signal from a flexible disk controller. A timer measures the time between consecutive transitions. Numerical values from the timer are delayed in a buffer. Numerical times from the buffer are compared to numerical ranges by an array of parallel numerical comparators. Numerical times corresponding to precompensation ranges are numerically compensated. The compensated values are then used to control the time between transitions in a regenerated Write Data signal.

Abstract: An electronic switch for sampling a signal. A small switch is placed in parallel with a large switch. The large switch is opened first. Any residual charge from the large switch is compensated by a low impedance path through the small switch. Speed is maximized by providing high current capacity through the large switch. Noise is minimized by leaving only residual charge from the small switch. Example embodiments are provided for sampling both voltage and current signals.

Abstract: A test system for a digital integrated circuit in which internal states of the integrated circuit are captured non-destructively while the digital circuit is operating at normal clock speed. Cells for capturing states are sequentially connected into shift registers. Once internal states are latched within cells, the captured states are serially shifted out a test port while the integrated circuit continues to operate. State sampling is triggered internally via a software command or externally via an external signal synchronized to an internal clock.