| 摘要 |
PURPOSE:To give no effect to other data lines connected in parallel by keeping a high impedance for an output terminal part of a unit for attachment/detachment of a unit until a unit power supply and the earth potential have normal contacts with the device side. CONSTITUTION:Each of units 8a-8n which perform attachment/detachment of units contains an element 3 having an open collector and a transistor (Tr) 6 having its collector terminal connected to its emitter. The collector of the Tr 6 is connected to a unit output terminal, and the base of the Tr 6 is connected to a power supply. A unit 2 connects the units 8a-8n and consists of an NAND gate 5 and a load resistance 4. The unit 8 keeps a high impedance in a steady state until its own unit is selected. In addition, the Tr 6 is off with the output kept at a high impedance in a unit attachment/detachment mode although the earth potential of the unit is applied earlier than the power supply. |
