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 of microcomputers with rapid communication between concurrent processes on the same or different microcomputers.
This is a continuation of application Ser. No. 08/472,295, filed Jun. 7, 1995, now abandoned which is a continuation of application Ser. No. 08/066,489, filed May 24, 1993, now U.S. Pat. No. 5,491,359 which is a divisional of application Ser. No. 07/606,064, filed Oct. 30, 1990, now U.S. Pat. No. 5,243,698, which is a divisional of application Ser. No. 06/938,380, filed Dec. 9, 1986, now U.S. Pat. No. 4,967,326, which is a continuation of application Ser. No. 06/553,027, filed Nov. 16, 1983, now abandoned.
Various embodiments of a programmable logic controller and a system for programming a programmable logic controller are disclosed. One PLC embodiment comprises an I/O component, a processor, a memory component and a kernel, all contained within a chip.
A nonvolatile storage element of a single-layer gate type structure is arranged so that a floating gate is formed of a conductive layer which partly overlaps with a control gate, formed of a diffused layer, and is provided with a barrier layer covering a part of or the whole surface of the floating gate. Nonvolatile storage elements characterized as such are used for redundancy control of defects or change of functions.
A multiprogrammed multiprocessor system comprises a plurality of processors and some communications resources such as networks through which the processors communicate with each other. A plurality of tasks may be executed on the system, and the allocation of the communications resources among the tasks is globally controlled. The allocation of resources among the tasks running on the system can be dependent on the signature of the tasks, where one component of a task signature is a measure of the communication resources needed by the task. The scheduling of a task running on the system may also be dependent on the signature of the task. The allocation of communications resources can be globally controlled using a variety of techniques including: packet injection into the communications resources using periodic strobing or using global flow control; using global implicit acknowledgments; by destination scheduling; by pacing; or by prioritized communication scheduling. Error recovery overheads can be amortized over a plurality of jobs running at one node. A user interface allows a plurality of service level options to be specified by a user, where the system can guarantee that the service levels can be achieved. Application users as well as system administrators can choose options as are appropriate. The user interface can allow the system administrator to run a scheduling mechanism that distributes communications resources among the tasks according to a market mechanism. The user interface can also allow a task to be guaranteed a fixed fraction of the resources independent of the other tasks then running or to be run as an interactive continuous job at one of a plurality of service levels. Finally, the user interface allows a system administrator to subdivide system resources into reserved and unreserved components, where the unreserved component is made available according to a market mechansim.
A nonvolatile storage element of a single-layer gate type structure is arranged so that a floating gate is formed of a conductive layer which partly overlaps with a control gate, formed of a diffused layer, and is provided with a barrier layer covering a part of or the whole surface of the floating gate. Nonvolatile storage elements characterized as such are used for redundancy control of defects or change of functions.
A nonvolatile storage element of a single-layer gate type structure is arranged so that a floating gate is formed of a conductive layer which partly overlaps with a control gate, formed of a diffused layer, and is provided with a barrier layer covering a part of or the whole surface of the floating gate. Nonvolatile storage elements characterized as such are used for redundancy control of defects or change of functions.
