Abstract: A method and system for reclaiming memory space occupied by replicated memory of a multiple computer system utilizing a replicated shared memory (RSM) system or a hybrid or partial RSM system is disclosed. The memory is reclaimed on those computers not using the memory even though one (or more) other computers may still be referring to their local replica of that memory. Instead of utilizing a general background memory clean-up routine, a specific memory deletion action (177A) is provided. Thus memory deletion, or clean up, instead of being carried out at a deferred time, but still in the background as in the prior art, is not deferred and is carried out in the foreground under specific program control.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. Contention detection and resolution is disclosed. A count value (99) indicative of the cumulative number of times each memory location has been updated is utilized. Contention is indicated if the currently stored count value and the incoming updating count value are the same. A method of echo suppression and a method of echo rejection are disclosed.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. In particular a method of broadcast memory updating with contention detection and resolution is disclosed which utilizes either a single or plural count value(s) and/or single or plural resolution value(s) for multiple memory locations. The count value is indicative of the number of the sequence of occasions on which a memory location has been updated.

Abstract: A multiple computer system with hybrid replicated shared memory is disclosed. The local memory (10, 20, . . . 80) of each of the multiple computers M1, M2, . . . Mn is partitioned into a first part (11, 21, . . . 81) and a second part (12, 22, . . . 82). Each of the first parts are identical and each of the second parts are independent. The total memory available to the system is the first memory part plus n times the second memory part, n being the total number of application running multiple computers.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. Contention detection and resolution is disclosed. A count value (99) indicative of the cumulative number of times each memory location has been updated is utilized. Contention is indicated if the currently stored count value and the incoming updating count value are the same. A method of echo suppression and a method of echo rejection are disclosed.

Abstract: A system and method for interconnecting multiple computers (M1, M2, . . . , Mn) via at least two communications networks (N1, N2, N3) are disclosed. The connections are made via multiple communications ports (28, 38). Data is sent and received via a data protocol which identifies the sequence position of each data packet in a transmitted sequence of data packets. The packets can be transmitted and/or received out of order. The multiple computers each execute a different portion of an applications program written to execute on a single computer.

Abstract: A method and system for reclaiming memory space occupied by replicated memory of a multiple computer system utilizing a replicated shared memory (RSM) system or a hybrid or partial RSM system is disclosed. The memory is reclaimed on those computers not using the memory even though one (or more) other computers may still be referring to their local replica of that memory. Instead of utilizing a general background memory clean-up routine, a specific memory deletion action (177A) is provided. Thus memory deletion, or clean up, instead of being carried out at a deferred time, but still in the background as in the prior art, is not deferred and is carried out in the foreground under specific program control.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. In particular a method of broadcast memory updating with contention detection and resolution is disclosed which utilizes either a single or plural count value(s) and/or single or plural resolution value(s) for multiple memory locations. The count value is indicative of the number of the sequence of occasions on which a memory location has been updated.

Abstract: A multiple computer environment is disclosed in which an application program executes simultaneously on a plurality of computers (M1, M2, . . . Mn) interconnected by a communications network (3) and in which the local memory of each computer is maintained substantially the same by updating in due course. A lock mechanism is provided to permit exclusive access to an asset, object, or structure (ie memory location) by acquisition and release of the lock. In particular, before a new lock can be acquired by any other computer on a memory location previously locked by one computer, any updating count(s) for the previously locked memory location are transmitted to all the other computers and their corresponding memory locations (before the in due course updating). Thus the lock acquiring computer can ascertain if its local memory has been adequately updated.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. In particular a method of detecting and resolving contention is disclosed which utilizes a count value indicative of the number of the sequence of occasions on which each memory location has been updated. Contention is indicated if the currently stored count value and the incoming updating count value are the same. The contention can be resolved by providing a further rule.

Abstract: In a system such as a multiple computer system where memory locations (A, B, C) can be substantially simultaneously updated from difference sources, an updating count (C, C1) is provided indicative of the sequence of each updating message or signal (195, 295) in a stream of such updating messages or signals. The updating count is stored in a counter. To reduce the storage requirements for the counter and the bandwidth requirements for the updating messages including the count value, small count values are utilized. From time to time sending of updating messages is halted and the count values re-set to avoid arithmetic overflow.

Abstract: An architecture for multiple computer systems which incorporates redundancy is disclosed. For each group of “n” first computers M1/1, M2/1, . . . Mn/1, a second “mirror” group of computers M1/2, M2/2 . . . Mn/2 is provided. Changes to the memory locations of each computer of the first group are communicated to the corresponding computers of the second group to update a replicated memory. Memory locations (A/1, B/1, C/1) stored on one machine (M2/1) and the mirror machine (M1/2) are stored on both the hierarchically adjacent machines M1/2, M2/2 and maintained updated. In the event of the failure of one machine, the mirror machine has the memory locations of the failed machine and is able to resume or take over the computational tasks of the failed machine thereby providing a first measure of redundancy. In the event of failure of both a first group machine and its mirror machine, the hierarchically adjacent mirror machine is able to resume or take over.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. In particular a method of detecting contention is disclosed which utilizes a count value indicative of the number of the sequence of occasions on which each memory location has been updated. Contention is indicated if the currently stored count value and the incoming updating count value are the same.

Abstract: An architecture for multiple computer systems which incorporates redundancy is disclosed. For each group of “n” first computers M1/1, M2/1, . . . Mn/1, a second “mirror” group of computers M1/2, M2/2 . . . Mn/2 is provided. Changes to the memory locations of each computer of the first group are communicated to the corresponding computers of the second group to update a replicated memory. Both distributed shared memory (DSM) and replicated shared memory (RSM) are disclosed.

Abstract: A multiple computer system incorporating redundancy is disclosed. Data to be stored (A, B, C) is distributed (A1, A2, A3, . . . B1, B2, B3, . . . C1, C2, C3, . . . ) amongst a multiplicity of computers (M1, M2, . . . Mn). A parity form (P[A], P[B], . . . ) of the stored data is created by use of a reversible encoding process. The parity form data is preferably cycled amongst the various computers. In the event of failure of one of the computers the lost data can be re-generated.

Abstract: A multiple computer system is disclosed in which the local memory of each computer (M1, M2, . . . Mn) can be different having some memory locations (A, B) which are replicated in other computers and other memory locations (E) which are not. When any computer seeks to acquire or release a synchronizing lock a check (171, 181) is made to see if the relevant memory location is present on any other machine. If yes, synchronization is carried out.

Abstract: An architecture for multiple computer systems which incorporates redundancy is disclosed. For each group of “n” first computers M1/1, M2/1, . . . Mn/1, a second “mirror” group of computers M1/2, M2/2 . . . Mn/2 is provided. Changes to the memory locations of each computer of the first group are communicated to the corresponding computers of the second group to update a replicated memory. Both distributed shared memory (DSM) and replicated shared memory (RSM) are disclosed.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. Contention detection and resolution is disclosed. A count value (99) indicative of the cumulative number of times each memory location has been updated is utilized. Contention is indicated if the currently stored count value and the incoming updating count value are the same. A method of echo suppression and a method of echo rejection are disclosed.

Abstract: A multiple computer system incorporating redundancy is disclosed. Data to be stored (A, B, C) is distributed (A1, A2, A3, . . . B1, B2, B3, . . . C1, C2, C3, . . . ) amongst a multiplicity of computers (M1, M2, . . . Mn). A parity form (P[A], P[B], . . . ) of the stored data is created by use of a reversible encoding process. The parity form data is preferably cycled amongst the various computers. In the event of failure of one of the computers the lost data can be re-generated.

Abstract: A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. Contention detection and resolution is disclosed. A count value (99) indicative of the cumulative number of times each memory location has been updated is utilized. Contention is indicated if the currently stored count value and the incoming updating count value are the same. A method of echo suppression and a method of echo rejection are disclosed.