Abstract: A method of fabricating a MOSFET wherein sidewall spacers are provided adjacent the gate of the MOSFET, the method including the steps of providing an insulating layer which extends over the source, drain and gate of the MOSFET and which acts as an impurity diffusion barrier; and forming on the insulating layer sidewall spacers which are composed of an insulating material.

Abstract: A semiconductor device comprising at least one semiconductor chip, the or each semiconductor chip having a plurality of chip bonding pads, a package which encloses the at least one semiconductor chip, a first level interconnect comprising a printed circuit which overlies the at least one semiconductor chip in the package and extends externaly of the package to provide a plurality of outer leads, and a second level interconnect comprising means for electrically connecting the chip bonding pads to selected contacts on the printed circuit, which contacts overlie the at least one semiconductor chip. The invention also relates to a method of manufacturing such a semiconductor device and to a method of assembling a semiconductor assembly.

Abstract: A method of forming a well of one conductivity type in a silicon substrate having a first surface region thereof which is doped with a dopant of one conductivity type and a second surface region thereof which is doped with a dopant of opposite conductivity type. The first and second regions are covered by respective first and second portions of an oxide layer which has been grown on the silicon substrate, the first portion being thicker than the second portion. The substrate is oxidized thereby to increase the thickness of the oxide layer such that the difference in thickness between the first and second portions is reduced. The substrate is also heated to cause diffusion of the dopant of one conductivity type thereby to form a well and of the dopant of opposite conductivity type down into the substrate. The heating step is carried out before, during or after the oxidizing step.

Abstract: A line delay device comprises a memory having RAM cells in two blocks, each cell being connected to a pair of bit lines. Memory locations in one block are addressed sequentially and subject to a data transfer while an equate operation is effected on the bit lines of the other block. The operations are switched alternately between the two blocks. In each accessing cycle, a plurality of locations are addressed in selected rows of each block and the switching between each block is effected without addressing all locations in each row addressed so that the accessing cycle ends in a different block from the starting block and each row used has a plurality of addressed locations.

Abstract: A microcomputer comprises an integrated circuit device with processor and memory and communication links arranged to provide non-shared connections to similar links of other microcomputers. The communication links include message synchronisation and permit creation of networks or microcomputers with rapid communication between concurrent processes on the same or different microcomputers.

Abstract: A microcomputer has a processor arranged to share its time between a plurality of concurrent processes. Each process may have means (69) for indicating a time when the process may be executed. The processes may form a linked list of processes (T, U. V) awaiting scheduling for execution. A location (90) is provided for indicating the beginning of a timer list of processes awaiting execution and means (68) is provided for indicating the end of a timer list. The microcomputer may provide more than one timer list of processes of different priority. Each process may include a number of alternative components one or more of which is time dependent.

Abstract: Single chip microcomputers with program stored in on-chip RAM combined by non-shared communication links each having an input channel and an output channel, each channel having a data register and process register used for synchronizing processes executed in different microcomputers in an array. Each process on a chip has a workspace. Constant bit size instructions have function and data portions. Scheduling/descheduling of processes in each microcomputer occur by forming a linked list in the workspaces for active processs. Each workspace identifies the next process to be executed and the next instructon for its own process.

Abstract: Multistage digital signal multiplying and adding apparatus suitable for a multistage filter includes a plurality of addition stages each having adding devices for forming a succession of partial products together with selectors operable in a first condition to connect sum and carry outputs of the adding devices within a stage to further adding devices within the stage or a second condition to supply outputs to a further stage, the selectors being operable to change condition without resolving carry signals in one stage through all bit positions of that stage. The output of one stage is connected to a subsequent stage during a first cycle of product formation of the subsequent stage so that the output is accumulated with the first partial product of the subsequent stage.

Abstract: In a semi-conductor memory cell components are formed in regions separated from each other by one or more insulation layers (40) and first and second load resistors (20,22) and gate regions (70,72) of first and second cross-coupled driver field effect transistors (16,18) are formed in a first conductive layer (64) and the word line (36) and gate regions (66,68) of first and second transfer transistors (28,30) are formed in a second conductive layer (60).

Abstract: A digital switch for selectively interconnecting a plurality of devices, including microcomputers, in a network comprises a plurality of inputs, a plurality of outputs and selectively operable interconnections which include decoding means for decoding data and acknowledgement bit packets, clock means, and means for generating under control of clock signals output bit packets having bit signals corresponding to bits of input bit packets.

Abstract: A multi-stage apparatus has an input which is coupled to an output by way of a plurality of first stages. The stages are sequentially coupled together to form a chain. A spare stage, which is substantially identical to at least a selected one of said first stages is also provided. The apparatus also includes programmable logic means arranged to uncouple said selected first stage from said chain and to couple said spare stage into said chain such that the input remains coupled to the output by the same number of stages. In this way a redundancy scheme for the multi-stage apparatus is implemented.

Abstract: A microcomputer comprising memory and processor is arranged to execute a plurality of concurrent processes and share its time between them. The microcomputer includes means for indicating a current process as well as a collection of processes awaiting execution. Processes may be added to the collection. Next process indicating means is provided to indicate the next process to be executed. Synchronization means is provided to synchronize communication between concurrent processes on the same microcomputer or interconnected microcomputers. The synchronization means may schedule a process by adding it to the collection or terminating execution of the current process.

Abstract: A communication interface for effecting communication by serial bit packets on unidirectional non-shared lines comprises a packet generator 70 arranged to output a byte of data in a data packet of a first format or an acknowledgement packet of a second format and a packet decoder 71 is arranged to decode incoming packets.

Abstract: A microcomputer comprising memory 60 and a process is arranged to execute a plurality of concurrent processes and share its time between them. The microcomputer includes as register (51) for indicating a current process as well as a collection of processes awaiting execution. Each process has a memory location 66 to provide an indication of a next process in a linked list of processes. Each process has an allocated priority and a separate linked list is formed for each priority. A register (53) indicates the front of one list and a further register (52) indicates the end of that list.

Abstract: A microcomputer method and system for executing a plurality of concurrent processes provides synchronized message transmission so that data is transmitted between a communicating pair of processes when the two processes are at corresponding program stages. The messages may be variable in length and are transmitted by indicating a source address for the data to be transmitted, a destination address for the data, and a count of the number of standard unit lengths of data to be transmitted in the message.

Abstract: A color graphics control system for generating red, blue and green analog signals to a raster scan display at a pixel frequency comprises a RAM storing a pluraltiy of digital color values, digital to analog converters for converting the digital color values into analog signals, an interface to permit an external controller to write digital color values into the RAM locations, a timer including a pixel clock and RAM accessing means controlled by the timer to pipeline RAM accessing with a cycle time of more than one pixel period.

Abstract: A microcomputer comprises memory (60) and a processor including a plurality of channels (70) to enable data transmission between concurrent processes. An inputting process may input data through one of a plurality of alternative input channels (70). Data transmission occurs when both processes are at corresponding stages in their programs. If an inputting process finds that no outputting process is yet ready on any of the alternative channels the inputting process may be descheduled and synchronisation achieved by special values located in locations (67) in a workspace (60) for the process.

Abstract: A programmable, high speed, single chip microcomputer includes 4K of RAM, ROM, registers and an ALU. Program can be stored in the on-chip RAM. The first local variable of each process to be executed is a workspace pointer (WPTR), and each process has a respective workspace identified by its WPTR. For each process, addressing of other variables is relative to the current WPTR, which is stored in a workspace pointer register (WPTR REG). Instructions are constant bit size, having a function portion and a data portion loaded, respectively, into an instruction buffer (IB) and an operand register (OREGTR). Memory address locations are formed by combining the contents of the workspace pointer register and the operand register, or the contents of the A Register and the operand register. A set of "direct functions" obtains data from OREG. "Indirect functions" use the OREG contents to identify other functions, obtaining data from registers other than the operand register.

Abstract: A programmable, high speed, single chip microcomputer includes 4K of RAM, ROM, registers and an ALU. Program can be stored in the on-chip RAM. The first local variable of each process to be executed is a workspace pointer (WPTR), and each process has a respective workspace identified by its WPTR. For each process, addressing of other variables is relative to the current WPTR, which is stored in a workspace pointer register (WPTR REG). Instructions are constant bit size, having a function portion and a data portion loaded, respectively, into an instruction buffer (IB) and an operand register (OREGTR). Memory address locations are formed by combining the contents of the workspace pointer register and the operand register, or the contents of the A Register and the operand register. A set of "direct functions" obtains data from OREG. "Indirect functions" use the OREG contents to identify other functions, obtaining data from registers other than the operand register.

Abstract: A microcomputer system with a processor and memory operates concurrent processes with synchronized communication between pairs of processes. Each communicating process has program instructions including one communication instruction to output or input data. The processes executed by a processor are scheduled by identifying a collection awaiting execution and descheduled by interrupting execution of instructions by the process. A communication channel is used to hold a value indicating whether or not either of a pair of communicating processes has yet executed an instruction requiring communication through that channel. Each communicating process tests the channel contents, and if the other communicating process has not yet reached the corresponding communication instruction, the process is descheduled until both processes have reached corresponding program stages.