公开(公告)号：GB1168414A

公开(公告)日：1969-10-22

申请号：GB3545768

申请日：1968-07-25

Applicant: IBM

Inventor： ARULPRAGASAM JEGANANDARAJ AMAL ,  BINKS DENNIS CRAVEN ,  PINNELL MARTIN COXWELL ,  PRICE RICHARD LOWELL ,  TUFFILL HAROLD WILLIAM ,  VASILE VINCENT CHARLES ,  WAUGH ROBIN

IPC: G06F11/14 ,  G06F11/20

Abstract: 1,168,414. Data processing. INTERNATIONAL BUSINESS MACHINES CORP. 25 July, 1968, No. 35457/68. Heading G4A. In a data processing system, recovery log storage is connected via a recovery log buffer to predetermined data locations in a C.P.U. (central processing unit) for recording data therefrom, and is updated after predetermined intervals but only after error checking circuitry in the C.P.U. has indicated error-free data flow in the C.P.U. during the current interval. The output of main storage goes via error-correcting circuitry to both the C.P.U. and a main storage buffer (which holds the 7 latest items from main storage and their addresses). Instruction fetch and execution cycles occur alternately. Changes in various C.P.U. registers during execution cycles are followed by a recovery log buffer the contents of which are passed to the recovery log storage during the respective following fetch cycles except that detection of an error in the C.P.U. during an execution cycle freezes the recovery log buffer, recovery log storage and main storage buffer to permit subsequent resumption of the programme or instruction retry without data loss. The recovery log buffer may be an associative store holding only the new contents of the portions of the C.P.U. registers which have actually changed, together with tags identifying the register portions. The recovery log arrangements, including the main storage buffer, have a separate power supply. Changes in the C.P.U. during fetch cycles may be stored in the recovery log storage during execution cycles.