| 摘要 |
<p>1508698 Electronic locks J W CANNON 8 July 1976 [26 Sept 1975] 28428/76 Heading E2A [Also in Division G4] A card - operated programmable access - control device includes an electronic memory having a permit code section and a void code section, a programmer (claimed separately) for storing in the memory also being provided. When a magnetically - coded card is inserted into the access - control device, reed switches sense therefrom an individual code, a master code and card presence. If the master code agrees with one built into the device, presence of the card causes power to be supplied to the rest of the circuitry wherein the individual code addresses a permit bit and a void bit in a ROM i.e. read - only memory (or an erasable memory could be used). If the permit bit is set but the void bit is not set, a door strike solenoid is energised. A hand - held programmer used for setting bits in the ROM has a projecting tongue which is inserted in place of the card and operates the reed switches for master code and card presence. Thumb wheels provide the address for the ROM and two buttons control setting of the permit bit and void bit respectively. One of three lamps (permit, void, clear) is lit to indicate the stored states using three diodes with different thresholds to convert the two memory bits to one - out - of three form. Setting of bits is done via the memory outputs.</p> |
