Abstract: A serial data interface device is coupled to electronic devices or other data transmitters or receivers, such as disk, optical, tape or CD-ROM drives, computers, printers, etc. The interface includes first and second ports capable of receiving and transmitting information to respective electronic devices, and first and second storage devices, such as frame buffers, for storing information. Each of the storage devices is coupled to both the first and second ports and are coupled to another electronic device. Included in each storage device is a main memory that is coupled to at least one of the electronic devices and at least one of the ports. A control memory that is coupled to the main memory is also included, along with a main memory arbiter that is coupled to the control memory and the main memory. Further included is a buffer allocation control that is coupled to the at least one electronic device and at least one of the ports.

Abstract: A method in a data processing system for identifying hazards in a circuit. Signal paths are identified in the circuit. Each signal path within the plurality of signal paths begins at a source and ends at a target and each signal path within the signal paths is one that potentially propagates a hazard. Errors are then identified in signal paths in the circuit by analyzing the timing relationships and hazard characteristics of the signals within the signal paths.

Abstract: An apparatus and method for improving the input/output performance of a computer system under the control of a multi-tasking, multi-threaded operating system. In particular, the invention provides an apparatus and method to chain contiguous DMA scatter gather sub blocks of a PRD table for channel 0 with contiguous DMA scatter gather sub blocks of a PRD table for channel 1, using a single data manager, while maintaining maximum media bandwidth. DMA block transfers are scheduled based on the availability of data from the I/O device's buffer memory, thus minimizing both media or network idle time as well as minimizing I/O bus idle time. Near maximum aggregate bandwidth of multiple I/O buses and their associated devices is obtained. The apparatus and method thus provides significant performance advantages over prior techniques having two I/O channel systems implemented with a single data manager.

Abstract: An integrated circuit formed on a semiconductor substrate has a contact pad for communicating signals between an external device and an internal signal line. The pad is protected by an SCR that conducts electrostatic discharge pulses from the pad directly to a current sink. The SCR includes a subregion underneath a field oxide that has a field inplant that increases the dopant concentration. The field implant lowers the SCR trigger voltage, so that SCR triggers before an ESD pulse can cause latch-up or damage in other devices in the integrated circuit.

Abstract: An integrated circuit includes a substrate and at least two circuits, such as a digital circuit and an analog circuit. The substrate is preferably derived from a bulk substrate wafer. The integrated circuit preferably comprises at least two islands in the substrate for noise isolation between the circuits. The two islands are buried-layers that are implanted, by preference, using conventional MeV techniques. A method of manufacturing an integrated circuit includes a substrate and at least two circuits. The method comprises the step of implanting at least two islands in the substrate for noise isolation between the circuits. The implanting is accomplished by conventional masking and high-energy implantation, such as MeV.

Abstract: The present invention is directed to a low-power input buffer comprising an inverter coupled to receive a first safe voltage range to a first node and coupled to provide an output signal, and a low-power circuit coupled to receive a second safe voltage range and coupled to control a voltage at the first node in response to the output signal and the second safe voltage range. The first and second safe voltage ranges preferably are equivalent. The low-power circuit includes series transistors coupled to the first node and responsive to the voltage at the output node. The low-power circuit further includes a transistor coupled between the first and second nodes and responsive to an input voltage. A method of operating an input buffer comprises the steps of pulling up a voltage of a first node in response to voltages of a second node and an output node and pulling down the voltage at the first node and the second node in response to an input voltage to provide low power consumption and a high impedance input.

Abstract: The present invention includes at least two variable-resistive devices, such as transistors, coupled to a resistive device, such as a resistor. The transistors are configured so that feedback voltage generated by respective currents of the transistors is applied to the gate of at least one of the transistors. The electrical characteristics of the other transistor changes proportionately greater than the characteristics of the one transistor. With this configuration, a variation-compensated current device is provided.

Abstract: A method an corresponding apparatus for improving the input/output performance of a computer system under the control of a multi-tasking, multi-threaded operating system. In particular, the invention provides an apparatus and method to interleave contiguous DMA scatter/gather sub blocks of a PRD table corresponding to a first I/O channel with contiguous DMA scatter/gather sub blocks of a PRD table corresponding to a second I/O channel, using a single data manager, while maintaining maximum media bandwidth. DMA block transfers are scheduled by the single data manager based on the availability of data from the I/O devices' buffer memories, thus minimizing both media or network idle time as well as minimizing I/O bus idle time. Near maximum aggregate bandwidth of multiple I/O buses and their associated devices is obtained. The apparatus and method thus provides significant performance advantages over prior techniques having two I/O channel systems implemented with a single data manager.

Abstract: A circuit for embedding within a SCSI control device for generating REQ or ACK signals in a flexible manner as required for SCSI synchronous data transfer mode. The circuit of the present invention utilizes a single counter and associated logic to provide flexible waveform generation of the REQ or ACK signal in a SCSI control device. The counter value counts up from zero and is compared against one of two values applied to a comparator. The first value is the desired period (duration) of the assertion of the REQ/ACK signal. When this count value is reached, the counter is restarted, the REQ/ACK signal is de-asserted, and the second count value--the de-assertion time--is applied to the comparator. When the second count is reached, the cycle starts over. An enable and reset signal allow other portions of the SCSI control device to start, stop, and reset the counter circuit of the present invention as required for SCSI synchronous data transfer controls.

Abstract: A pad is adjacent a hole that will be located on the trailing edge of the board when the board is processed through wave soldering. The pad includes a curved side that faces the hole. In addition, corners are absent from the pad. The intersections of sides of the pad occurs as a curve or radiused corner, rather than a verticed corner. Wave soldering the printed circuit board with the pad greatly reduces bridging of a lead inserted into the hole adjacent the pad.

Abstract: A CMOS voltage level shifter that is comprised of a pull-up device coupled between a first voltage supply and an node to pull up that node to the voltage of the first voltage supply. The pull-up device is responsive to a first voltage signal. A pull-down device is also included that is coupled between the node and a reference voltage supply to pull down that node to a voltage of the reference voltage. The pull-down device is responsive to second and third voltage signals. A feedback circuit is included that provides the second voltage signal to the pull-down device. A level shifted output voltage signal is provided at the node.

Abstract: A picture element sensor circuit in an image array scanner is tested by driving a reset FET with a controllable voltage to set the reverse-bias voltage across the photo-diode at any selectable level of test voltage. In this way each pixel sensor circuit in the array may be tested as if it had received a desired amount of illumination. Alternatively, the drive voltage for the reset transistor is provided over the column output line. The controllable test voltage can be applied to the column line when no row access enable signal is applied to the array. In this situation the column line source follower circuit is inhibited by the row access FETs. Thus, a separate test voltage can be driven onto the column line, through a reset switch, and connected through the pixel sensor reset transistor to the pixel sensor photo-diode. The variable reset voltage, that is driven onto the column line, can be varied between ground and the normal bias voltage V.sub.

Abstract: An ESD protection system that makes use of several different types of over-voltage protection devices provides ESD conduction paths between different power lines. For example, the system may employ shunt diodes between the ground lines of the different power supplies and between I/O pads and power supply lines; SCR protection between I/O pads and ground; and thick field device protection between different power supply V.sub.DD lines. In this way, a conduction path for an ESD event between two input, output power and ground pads may be implemented using the device whose switching characteristics are best suited to that application.

Abstract: A directional antenna connected to a portable communications transceiver is adaptively directed towards a remote station in a communication system. The amount of RF power required by the portable device is significantly reduced, relative to a non-directional antenna. The operational period of the transceiver between battery recharges is therefore considerably maximized.

Abstract: A CMOS disk drive motor control circuit which has back-EMF regulator circuitry which prevents the back-EMF from the disk drive motor from exceeding a predetermined level. The back-EMF provides an alternate power source for parking the read/write head when power is removed from the disk drive. The circuit is fabricated as a single CMOS integrated circuit which is coupled between a power supply and the disk drive motor. The disk drive control circuit also includes a blocking diode through which power from the power supply flows to the motor and which prevents dissipation of a back-EMF from the motor when power is removed from the motor, and disk drive head parking circuitry which uses the back-EMF to retract and park the disk drive head.

Abstract: A digital data separator is provided for separating clock information and data from a data stream which is subject to varying amounts of undesired jitter which tend to corrupt the data. A read data window of controlled duration is generated for sampling the input data. The current best estimate of the duration of the read data window is stored in a period register as a period register value. The period register value minus one is loaded into a time register as the time register value. A count down cycle is performed by subtracting a value of one from the time register value in each clock cycle during the course of the count down cycle. The read data window is toggled to begin a new read data window when the time register value is near zero, the value remaining in the time register being designated the remaining value.

Abstract: A method and apparatus for transferring data between two relatively asynchronous devices and yet matching the maximum data rate of each. Both an asynchronous FIFO and a synchronous FIFO are used to match the data rate of a high speed asynchronous device, such as a SCSI/SCSI2 controller, to a high speed synchronous device, such as a DMA controller. A high speed synchronizer controls both FIFOs such that the asynchronous and the synchronous devices can each run at its maximum data transfer rate during operation.

Abstract: A high efficiency charge pump for low and wide voltage ranges. The charge pump includes main and secondary charge pumps, the secondary charge pump is employed to avoid the Vt.sub.N drop that the main charge pump exhibits. The secondary charge pump allows the main charge pump to pump to a theoretical maximum of 2 VCC, while maintaining an efficiency close to 40%.

Abstract: A memory device circuit that alters the input refresh addresses to access fewer memory cells to save power, or to address more memory cells to decrease the refresh time. The circuit contains a simple transistor configuration that blocks certain address bits, then substitutes active bits in their place to the address decoder. The circuit also includes a controller that is responsive to the memory device entering the refresh mode. When the device is used in refresh mode, the address bits may be passed unblocked to the address decoder for full user control.

Abstract: A row decoder that includes circuitry to provide a self-timed bootstrap signal. The self-timed bootstrap signal is generated in response to the selection of the row decoder. At the same time, a capacitive device is charged in order to bootstrap a word line. The self-timed bootstrap signal causes a clock generator circuit to output a clock signal that will be used to bootstrap the word line. The self-timed bootstrap signal may be generated by other row decoders. The generation of the self-timed bootstrap signal by a row decoder is responsive to any variations in that decoder, thus always providing an accurate and precise timing of the clock signal to be used for the bootstrapping.