| 摘要 |
PURPOSE:To allocate identification numbers without need to reset by storing a virtual identification number in a card loaded onto a bus, accessing each card by this number and providing a master card updating said number to an inherent identification number. CONSTITUTION:If the virtual identification number that the not shown master card outputs to an address line coincides with the identification number held in the card, a card newly inserted into a system at the time of an active line becomes able to fetch data. A comparator 1 decides the coincidence. The master card 1 executes such operations as to output the individual identification number corresponding to one bit through one access in a slot position of zero in increasing order. When the bit position corresponding to the inserted slot position becomes active, a latch signal also becomes active. Therefore, the card fetches the individual identification number to a register 2b, and writes said number in a register 2a. Through the use of the individual identification number, the master card can access normally. |
