公开(公告)号：GB1240978A

公开(公告)日：1971-07-28

申请号：GB1446870

申请日：1970-03-25

Applicant: IBM

Inventor： PINNELL MARTIN COXWELL ,  TALMADGE RICHARD BENNETT

IPC: G06F9/48

Abstract: 1,240,978. Data processing. INTERNATIONAL BUSINESS MACHINES CORP. 25 March, 1970, No. 14468/70. Heading G4A. A data processing system with a multi-level priority interrupt facility, includes pseudo-interrupt means whereby, if an owner of a data structure (i.e. a procedure which requires exclusive right to access the data structure) is in an interrupted state and subsequently a procedure initiated by a higher priority interrupt requests the same data structure, a pseudointerrupt is generated to suspend the requester and force execution of the owner until it releases the data structure. A chain of save areas is provided in storage, each to receive system status on interrupt or pseudo-interrupt and to reload the system on return. The areas are chained together in both forward and reverse directions, having four pointer locations each, for this purpose. System status comprises a PSW and the contents of general purpose and floating-point registers. A list of new PSWs, addressable using the interrupt level identity, is provided, each PSW being accompanied by an indication of which registers are to be saved. The list also includes PSWs for housekeeping functions. A bit in the active PSW can selectively prevent or permit all interrupts. The possible interrupts are also subject to individual masking bits.