Abstract: In response to receiving TCP inbound message packets from a remote node, a network node buffers the received TCP message packets in a receive queue. The network node forwards the inbound message packets to an application node. Socket states, excluding receive-queue contents, are sent to a backup node. In response to receiving acknowledgements corresponding to respective inbound message packets from the application node, the network node sends respective acknowledgements from the network node to the remote node.

Abstract: In response to receiving TCP inbound message packets from a remote node, a network node buffers the received TCP message packets in a receive queue. The network node forwards the inbound message packets to an application node. Socket states, excluding receive-queue contents, are sent to a backup node. In response to receiving acknowledgements corresponding to respective inbound message packets from the application node, the network node sends respective acknowledgements from the network node to the remote node.

Abstract: In response to receiving TCP inbound message packets from a remote node, a network node buffers the received TCP message packets in a receive queue. The network node forwards the inbound message packets to an application node. Socket states, excluding receive-queue contents, are sent to a backup node. In response to receiving acknowledgements corresponding to respective inbound message packets from the application node, the network node sends respective acknowledgements from the network node to the remote node.

Abstract: In response to receiving TCP inbound message packets from remote node, a network node buffers the received TCP message packets in a receive queue. The network node forwards the inbound message packets to an application node. Socket states, excluding receive-queue contents, are sent to a backup node. In response to receiving acknowledgements corresponding to respective inbound message packets from the application node, the network node sends respective acknowledgements from the network node to the remote node.

Abstract: A method and system of copying a memory area between processor elements for lock-step execution. At least some of the illustrative embodiments may be a method comprising executing duplicate copies of a first program in a first processor of a first multiprocessor computer system and in a first processor of a second multiprocessor computer system (the executing substantially in lock-step), executing a second program in a second processor element of the first multiprocessor computer system (the first and second processors of the first multiprocessor computer system sharing an input/output (I/O) bridge), copying a memory area of the second program executing in the second processor element of the first multiprocessor computer system to a memory of a second processor element in the second multiprocessor computer system while the duplicate copies of the first program are executing in the first processor elements, and then executing duplicate copies of the second program in the second processors in lock-step.

Abstract: A method and system of copying memory from a source processor to a target processor by duplicating memory writes. At least some of the exemplary embodiments may be a method comprising stopping execution of a user program on a target processor (the target processor coupled to a first memory), continuing to execute a duplicate copy of the user program on a source processor (the source processor coupled to a second memory and generating writes to the second memory), duplicating memory writes of the source processor and duplicating writes by input/output adapters to create a stream of duplicate memory writes, and applying the duplicated memory writes to the first memory.

Abstract: A computer system includes a primary processor and a secondary processor running in lockstep. The lockstep may or may not be synchronous. Errors occurring in the primary processor or the secondary processor are reported to an error-handling module. If the error is a recoverable error, the state of one of the processors is saved and the processors are restarted using the saved state. In addition to the reporting of errors from the processors, cross checking of the operation of the processors is performed to detect a divergence in the operation of the processors. If the divergence is reported to be due to a recoverable error, the state of the one of the processors is saved and the processors are restarted using the saved state. Procedures are also disclosed to ensure that data corruption does not propagate onto an associated network, and to ensure that the system is not lost as a network resource during processor restart.

Abstract: A processing system includes a pair of processor coupled in a lockstep arrangement. The pair of processors is coupled to a storage element that is external to the both of them. Each processor executes an instruction stream that is identical to that executed by the other. Dissimilar information can be exchanged between the processors by each writing the information they wish to exchange to a first storage location with identical instructions. Although both processors execute the write with the same address, the information written by one of the processors is redirected to a second storage location. Each processor then reads the first and second storage locations to retrieve information supplied by the other processor. Now each processor has a copy of the other's data while staying in lockstep.

Abstract: A computer system includes a primary processor and a secondary processor running in lockstep. The lockstep may or may not be synchronous. Errors occurring in the primary processor or the secondary processor are reported to an error-handling module. If the error is a recoverable error, the state of one of the processors is saved and the processors are restarted using the saved state. In addition to the reporting of errors from the processors, cross checking of the operation of the processors is performed to detect a divergence in the operation of the processors. If the divergence is reported to be due to a recoverable error, the state of the one of the processors is saved and the processors are restarted using the saved state. Procedures are also disclosed to ensure that data corruption does not propagate onto an associated network, and to ensure that the system is not lost as a network resource during processor restart.

Abstract: Apparatus and method are disclosed for handling a flexible disk for testing. The apparatus includes guide rails for initially positioning a disk for test. The apparatus also includes a variable speed motor for rotating the disk at a preselected rotation speed. The disk is rotated by clamping the disk betwen a motor driven rotating spindle and a retractable collet. The collet passes through an aperture in the disk to center and position the disk. Testing is accomplished by a test head assembly which is moved by a voice coil actuator. Positioning of the test head assembly is controlled by a light detector and ground glass scale coupled to the actuator and to the test head assembly.

Abstract: An automatic disk testing apparatus and method for testing flexible disks is disclosed. The apparatus includes a gravity feed disk hopper and vacuum disk plate which sequentially present a series of disks for test. Each disk drops by gravity from the vacuum disk plate to a test position including a drive mechanism. The drive mechanism rotates the disk, in its disk jacket, at a predetermined rotational speed for testing. Each disk is tested and the test results are stored in memory. After testing, the disk is automatically sorted and moved to an output location based on the test results. The sorting is accomplished by dropping the tested disk into a motor driven shuttle which conveys the disk to the proper output location and drops the disk at that location.

Abstract: An automatic disk positioning apparatus and method for its use in handling of flexible disks in an automatic testing apparatus is disclosed. The apparatus includes a gravity feed disk hopper and vacuum disk plate which sequentially present a series of disks for test. Each disk drops by gravity from the vacuum disk plate to a test position including a drive mechanism. The drive mechanism rotates the disk, in its disk jacket, at a predetermined rotational speed for testing. Each disk is tested and the test results are stored in memory. After testing the disk is automatically sorted and stored in an output container based on the test results. The sorting is accomplished by dropping the tested disk into a motor driven shuttle which conveys the disk to the proper output container and drops the disk into that container.