I/O system for off-loading operating system functions

Claim 1

In a processing system having a plurality of central processors and a memory for storing a plurality of processes to be executed by said central processors, the combination comprising: a task control processor providing for the scheduling of processes for execution by said central processors, said task control processor also keeping track of the status of waiting processes; an input/output processor coupled to said central processors and to said task control processor; and a plurality of devices coupled to said input/output processor; said central processors operating such that, when an executing process encounters an I/O operation, a corresponding input/output control block is created in said memory and an input/output instruction is initiated which is sent to said input-output processor, said input/output instruction indicating the executing process, an operation to be performed, the identity of a device, and an input/output control block in said memory; said task control processor being responsive to the initiation of said input/output instruction to place the initiating process in a wait state until completion of said instruction by said input/output processor and to release the corresponding central processor to execute another process; said input/output processor being responsive to an input/output instruction sent thereto to fetch the corresponding input/output control block in said memory for use in performing the indicated operation on the identified device, following which said input/output processor signals said task processor of the completion of the input/output operation; said task control processor being responsive to the completion of an input/output operation by said input/output processor for rescheduling the corresponding waiting process for further execution when a central processor becomes available.