Computer system with work stations at remote positions and reserve battery power supply

Claim 1

A computer system comprising: a central machine for processing data, said machine being adapted to be connected to a mains supply, said central machine including a volatile memory; a plurality of user work stations coupled to said central machine for remote users to exchange data with said central machine; reserve battery supply means connected to said central machine for temporarily supplying power to said volatile memory in the event said mains supply is interrupted; said central machine having four separate states: an active state, in which data exchange by said central machine with any of said work stations, including processing at said central machine can be carried out; a standby state, in which data exchange cannot be carried out between any of said workstations and said central machine but in which the volatile memory is powered by the mains supply for retaining information; a battery supply state in which the volatile memory is temporarily powered by the reserve battery supply means for retaining information; and a rest state, during which the central machine and volatile memory are deactivated and information stored in the volatile memory is lost; independently powered heart memory means operative during all said states for storing predetermined beginning and ending times for the active state and including real time clock means and means for setting said central machine in said active state during an active time period beginning at said beginning time and ending at said ending time; each said workstation including user control means for generating an activate state request signal requesting to change the state of said central machine from said standby state to said active state; means for generating a battery-was-off signal in the event power from said reserve battery supply means was interrupted during said battery supply state; means, including said heart memory means, for storing indications of the condition of said computer system including said battery-was-off signal and an indication of whether an activate state request signal has occurred; and logic means responsive to the presence of power from said mains supply for selectively placing said central machine in said active state or said standby state based on inspection of said stored condition indications including means for initiating an initial program load if said mains supply power reappears during said active time period and said battery-was-off signal is present.