GB1178653A - Apparatus for Protecting Data Signals in Data Processing Equipment - Google Patents

Abstract

1,178,653. Computers; data stores. INTERNATIONAL BUSINESS MACHINES CORP. 25 July, 1968 [4 Aug., 1967], No. 35458/68. Headings G4A and G4C. In data processing equipment, voltage fluctuations in power supply lines indicative of a potential power failure are detected by means operable to distinguish between a catastrophic power failure in which data signals will be destroyed and a non-catastrophic power failure in which data signals may be protected, detection of a non-catastropic failure causing transfer of the contents of volatile data storage devices to a non-volatile store followed by initiation of an equipment switched-off procedure, and detection of a catastrophic failure causing initiation of the switch-off procedure immediately. In Fig. 1, D.C. supplies VNK, VK are obtained via voltage regulators SG from a filter-rectifier unit NG fed with the A.C. mains supply via relay contacts EMS. Imminent supply failure detected at US1 or US2, e.g. by overvoltage or undervoltage conditions, generate signals AS1 or AS2 to. produce signals KS1 or KS2 from logic LOG which respectively control short-circuit paths for capacitors C1, C2 (connected between the supply lines and earth) and set variable series resistors in the regulators SG to their maximum value (irrespective of the ordinary regulation control voltage RE). Production of either signal AS1, AS2 (representing faults which allow data in volatile storage to be saved) sets a first bi-stable, and production of other signals representing faults which do not allow such saving set a . second bi-stable. If the first bi-stable is set and the second is not, the contents of machine registers (using transistorized triggers-volatile) are stored in turn into the computer's: main memory (non-volatile) addressed by a constant address generator (for the first address) and a counter. The final count and an identification of the fault are then stored in the main memory. A machine switch-off sequence then follows. If both bi-stables were set, the switch-off sequence is initiated immediately (without register saving). In either event, setting of the first bi-stable also prevents a new instruction or micro-instruction being called or executed (though the current microinstruction is completed) and presently opens the relay contacts EMS. A sudden voltage increase in a line VNK, VK due to a shortcircuit in a regulator SG is mitigated by use of a silicon-controlled-rectifier which responds to the voltage (e.g. via an amplifier) to connect a resistor across the output load. Types of machine register saved are listed.