Abstract: A system for integrating an external numeric keypad with a keyboard on a portable computer wherein the keypad communicates with the system BIOS through the keyboard. The keyboard includes 82 or 83 keys and an internal keyboard controller connected to a switch matrix. The controller repeatedly scans the switch matrix to determine if one or more keys has been pressed and generates scan codes for the active keys which are then output to the computer BIOS. The keypad includes 17 numeric and cursor control keys. The keypad is controlled by an internal keypad controller which is connected to a switch matrix. The keypad controller scans the keypad switch matrix to determine if one or more keys has been pressed and to generate scan codes for the active keys. The scan codes generated by the keypad controller are sent to the keyboard controller through an auxiliary port in the computer system. The keyboard controller converts the scan codes received from the keypad controller into switch locations.

Abstract: A rotatable bushing for reducing bending fatigue on a flat cable between a display screen cover and a base of a portable computer comprises an elongate cylindrical body having a diametric slot therethrough. The bushing is positioned along the hinge axis between the cover and the base of the portable computer. The cable extends from the cover display screen, through the slot, and to circuitry within the base of the computer. MYLAR shields also extend through the slot on either side of the cable. When the cover is closed and opened over 180.degree., the cable applies force to the bushing, which is free to rotate as dictated by the force applied by the cable. The rotation of the bushing effectively provides two bending regions on the top and bottom of the bushing slot so that the cable does not bend through the entire range of motion of the cover at a single point. Since the bending of the cable is distributed, fatigue due to bending stress is significantly decreased.

Abstract: A keyboardless entry computer system includes a transparent input screen that generates positional information when contacted by a stylus, and a display screen mounted physically below the input screen such that a character that is displayed can be seen below the input screen. The system includes a computer that has been programmed to compile the positional information into Strokes, to calculate Stroke characteristics, and then compare the Stroke characteristics with those stored in a database in order to recognize the symbol drawn by the stylus. Key features of the system are: (1) transparent position sensing subsystem; (2) underlying display on which to mimic drawing of sensed positions and to show characters or symbols; (3) means to convert sensed positions first into plotted Points and then into recognized characters or symbols; and (4) means to "learn" to associate sensed input positions with a character or symbol.

Abstract: A Single Inline Memory Module (SIMM) support system enables a computer system to recognize and address 1-Mbyte, 4-Mbyte and 16-Mbyte SIMMs installed in a receiving socket having only a number of pins sufficient to address the 1-Mbyte and 4-Mbyte SIMMs. The capacity of the SIMM is determined by a TYPE signal on a predetermined pin of the installed SIMM which is connected to a pull-up resistor of the SIMM support circuitry and generates a TYPE signal. If the TYPE signal is a logic low, the installed SIMM has a 1-Mbyte capacity. If the TYPE signal is a logic high, the installed SIMM has a 4-Mbyte or a 16-Mbyte capacity. In order to remain pin compatible with 1-Mbyte and 4-Mbyte SIMMs, a 16-Mbyte SIMM cannot have any additional pins to address the additional memory locations. Thus, the TYPE signal shares a pin with the most significant address bit required to address the 16-Mbyte SIMM.

Abstract: A method for defining traces on a multi-layer circuit board suppresses electro-magnetic emissions radiated from the traces. The defined traces carry a differential signal. Layers of signal and return trace pairs are formed. Each succeeding layer of traces is spaced above and follows the traces below, with the succeeding signal trace positioned above the preceding return trace and the succeeding return trace positioned above the preceding signal trace. All of the signal traces are conductively connected and all of the return traces are conductively connected. The symmetry of the arrangement causes the electro-magnetic fields generated by the conductors (traces) to cancel at any appreciable distance. Additionally, varying combinations of layers and/or varying parameters such as dimension, spacing and dielectric material, results in a desired impedance for matching to external cabling and the like.

Abstract: A computer security device for preventing unauthorized access to a computer system automatically disables peripheral device access to the computer system after the peripheral input devices remain inactive for a predetermined period. The system comprises a host computer which is in communication with a keyboard controller and a display. The keyboard controller is in communication with one or more peripheral input devices such as a keyboard and a mouse. The computer security device operates in the keyboard controller, independent from the host. The keyboard controller activates security after a preset time period during which the mouse and keyboard remain inactive. When the security is active, the keyboard controller disables transfers to the host computer from the peripheral input devices. In order to re-enable peripheral device access to the host computer, a user enters a correct password on the keyboard. In a preferred embodiment, the display is also deactivated when security is active.

Abstract: A fingerpoint mouse includes an elastic finger pad having a recess formed therein. The recess is configured to receive a finger such as a user's index finger. A photo-diode attaches to the underside of the recess and photo-voltaic sensing cells form an array opposite the photo-diode beneath the recess. The user applies pressure to the fingerpad and thereby causes the diode to point in a direction opposite the direction of the applied pressure. The diode transmits light which impinges on one or more of the photo-voltaic sensing cells. The photo-voltaic cells generate voltage signals indicative of the direction of the pressure applied by the user on the fingerpad. The voltage signals produced by the photo-voltaic cells are decoded and converted to conventional mouse data. The mouse data is used to position a cursor on a graphics screen so that the user controls the movement of the cursor by applying pressure on the fingerpad in the direction of the desired cursor motion.

Abstract: A frequency divider state machine synchronously divides an input clock's frequency by 1.5. The clock divider circuit includes two storage elements which are clocked on different edges of the input clock signal. The outputs of the two storage elements are combined together using combinatorial logic, the results of which are provided back to the inputs of the two storage elements. Further, the two outputs of the memory storage elements are combined together to provide the desired output frequency. Preferably, the circuit is designed such that if either of the two memory storage elements powers up in an undesired state, the divide by 1.5 circuit will automatically transition to one of the desired states and continue to provide the output frequency at the desired divide by 1.5 clock frequency after the initial transition. The circuit can be implemented as a digital circuit in an ASIC, an LSI, or the like.

Abstract: A portable computer having a hinge assembly which allows the cover and display screen to be tilted from the base of the portable computer and then swiveled about a vertical axis. One hinge is provided at the rear edge of the base of the portable computer about which the cover both tilts and swivels. The hinge assembly includes stops which limit the amount of tilt and swivel. The cover of the personal computer may be tilted backwards from a closed position to 115.degree. and swiveled 30.degree. from a straight-forward position.

Abstract: A portable lightweight combination laptop and pad computer has a display mounted on a main housing for movement between a closed position and an open position. In the closed position, a keyboard is covered by the undersurface of the display and the display viewing surface remains visible so that the computer may be used in the pad mode with a conductive stylus for data and command entry. In the open position, the keyboard is exposed so that the computer may be used in a laptop or desk top mode, or in a combined mode including the pad mode. The display is mounted to the housing by a four bar hinge mechanism, and a pair of latches are provided approximately mid-way between the front and rear portions of the housing along the side margins to securely latch the display in the closed position for storage, transit or use in the pad mode.

Abstract: An ISA-compatible computer system includes an additional function key on its keyboard. The additional function key does not have a defined function for conventional ISA-standard computers. When a conventional alphanumeric key or function key is activated on the keyboard, the computer system is interrupted using IRQ1 and the key information is communicated to the computer system so that the computer system can respond in a conventional manner using a conventional keyboard interrupt handling routine. When the additional function key and an alphanumeric key are activated in combination, a second interrupt different from the IRQ1 interrupt is activated (e.g., IRQ15). The computer system responds to the second interrupt by inputting an identification of the activated alphanumeric key and performing a selected predetermined function in response thereto.

Abstract: An infrared remote-control system and method for the simultaneous transmission of data from two or more separate hand transmitters to a single remote-control receiver is disclosed. Interference between transmitted signals is eliminated by interlacing control signals with quiescent periods during transmission. The control signals are received and validated by the receiver based on the quiescent periods.

Abstract: An input buffer circuit for voltage controlled switch based logic, such as CMOS, which tolerates a floating input voltage without damaging the transistors which form the input buffer circuit. The input buffer circuit protects the input transistors by including an inhibit signal that can be activated to prevent the connection of the system power supply to the system ground when other input signals are floating. The inhibit signal or an independent protection signal further causes the buffer circuit to provide a constant output from the input buffer circuit even when the input voltage floats. Preferred embodiments of the input buffer circuit can be programmed from an internal or external source to cause the output of the buffer circuit to be at an inactive high level or to be at an inactive low level in accordance with whether the input signal being buffered is an inactive high signal or an inactive low signal.

Abstract: A system and method for recording on optical and electromagnetic disk media utilize a control disk for formatting and providing speed control of the recorded information. Optionally, the control disk may provide operating, diagnostic, and a wide variety of other information to the recording system or user. A recording disk and the control disk are rotated synchronously with each other while the control disk is scanned by a read head which derives formatting, speed control, and other information. A write head on the recording disk is then manipulated in a pattern determined by the formatting and speed control information. Typically, the read head and write head are mechanically coupled so that the write head is positioned as the read head follows a tracking information on a read surface of the control disk to write a tracking pattern to a write surface of the recording disk in a recordable region between a start-of-disk pattern and an end-of-disk pattern.

Abstract: A method and apparatus for expanding a backplane interconnecting bus provides an architecture in which the width of a data bus can be expanded without new byte select control lines on the backplane bus. In the present invention, data lines and corresponding parity lines are added to the backplane bus, and control signal lines connect devices capable of utilizing the expanded bus capabilities. The control signal lines do not affect the operation of devices which are designed according to the narrower bus width, and therefore, these devices can be installed in the expanded bus backplane along with devices designed to utilize the expanded width data bus.

Abstract: A shielded flexible cable includes a first shielding grid having conductive elements formed as squares. A second shielding grid is also formed as squares. The two shielding grids are positioned with respect to each other so that the vertices of the squares of the two grids are respectively offset from each other in each of two directions by one-half the diagonal distance between the vertices of the squares. Electrical signal conductors are positioned between the two grids along lines extending between the vertices of the squares to maintain a controlled impedance of the signal lines.

Abstract: A data log for use with conventional hard disk subsystems or other data storage subsystems provides a system to minimize delays caused in a computer system due to the input/output systems, such as hard disks. The data log is preferably one or more hard disks, or any other non-volatile data storage device. Preferably, when the operating system requests a write to the hard disk subsystem, a hard disk controller directs the data to the data log rather than the hard disks. Then, when I/O requests are at a lull, the hard disk controller moves the data from the data log to the hard disk subsystem. Because the data is written to the data log sequentially, the hard disk controller completes the write operation quickly. This minimizes any bottleneck created while the system waits for the completion of the write operation.