Multi-processor computer system

Claim 1

Apparatus for processing a plurality of discrete computing tasks, each expressed as a sequence of digital computer instructions, at least one task including a call instruction requesting the performance of a task specified by the call instruction, and at least one task including a task suspension instruction, comprising: (A) an addressable main memory recording digit sequences contained in a record signal responsive thereto at the address specified by an address signal, and supplying in a data signal the digit sequence recorded at the address specified by the address signal responsive to a retrieve signal, and storing within predetermined areas a plurality of tasks and a task description table specifying the information necessary for activation and execution of each task; (B) a storage access unit having a plurality of associated pairs of input and output channels, and supplying record, retrieve and address signals to the main memory responsive to record and retrieve-specifying function codes accompanied by data and an address signal on any one of the plurality of input channels; and supplying retrieved data sequences on the output channel associated with the input channel receiving the function code specifying the retrieve function; and (C) a plurality of local processors whose elements can store and retrieve data in the main memory via a preselected input and output channel pair of the storage access unit, each processor comprising: (1) an addressable local memory accessible to all other elements of the local processor and including a current task cell; (2) task activation means receiving a call task signal identifying a task for forming responsive thereto an active table entry specifying the location of the identified task in main memory and containing a multi-state status flag indicating a ready state, and for issuing signals to the storage access unit causing the active table entry to be stored in an unused area of an active table in the main memory, each said area identified by an associated index; (3) task selection means for issuing signals to the storage access unit to cause at least one active table entry to be retrieved from the main memory responsive to an idle signal, for examining the status flag in each active table entry retrieved, and for, responsive to the ready state of the status flag in any retrieved active table entry, setting the current task cell to the index of the active table entry having such a status flag, and thereafter issuing signals to the storage access unit for (a) changing the status flag in the active table entry in the main memory indexed by the contents of the current task cell to an execute state and, next, (b) retrieving the task whose location is specified by the active table entry indexed by the contents of the current task cell and storing it in the local memory; and (4) task execution means for (a) executing each task indexed by the current task cell responsive to its storage in local memory, (b) supplying the idle signal to the task selection means responsive to detection of a task suspension instruction, and (c) supplying the call task signal to the task activation means responsive to detection of a call instruction.