DATA PROCESSING SYSTEMS

摘要

1505603 Data processing systems INTERNATIONAL BUSINESS MACHINES CORP 7 July 1976 28257/76 Heading G4A When a data item is to be changed as a result of an operation thereon by the central processing unit of a data processing system (not shown), a copy of the data item is transferred from the main store of the central processing unit to a non-volatile store (not shown) via a buffer store 24, and control means such as a counter 26 and a clock generator 28 initiate a read-out of data items from the buffer store 24 to the non-volatile store whenever either a predetermined number N of data items has been stored in the buffer store 24 or a predetermined time has elapsed from the storing of the first data item in the buffer store 24, the predetermined number or predetermined time being increased/decreased according as the rate of data items fed to the buffer store 24 increases/ decreases. N data items are read-out at a time from the buffer store 24. In this way the central processing unit does not have to wait an inordinate time before a data item may be operated on, as the copy of the data item is transferred from the buffer store 24 to the non- volatile store after at most the predetermined time (which may be 1 second). The Nth output of the counter 26 and the output of the clock generator 28 control the read-out of the buffer store 24 via an OR gate 30 and a buffer store output register 32. If the Nth output of the counter 26 is produced before the output of the clock generator 28, the value of N is increased via an AND gate 36. In the opposite case, the value of N is decreased via an AND gate 34 Circuitry 38, 40 coupled to the AND gates 34, 36 maintains the value of N between predetermined limits. The system is a multi-processing system handling concurrent transactions from a plurality of peripheral devices, the buffer store circuitry being microprogram controlled. Alternatively, the buffer store operations may be controlled by software. Variable length or fixed length data items may be used. The main store may be a disc store and the non-volatile store a disc store or a tape store.