| 摘要 |
PURPOSE:To select the number of input/output parts more than that of address bus lines, by dividing address lines into plural groups, and selecting a sepcific input/output part by the AND condition between signals of those groups. CONSTITUTION:When an address line set by a switch 6X and an address line set by a switch 6y are both selected by output ports 10X and 10Y of a controller 2 at the same time, the input-side diode of a photocoupler 11 at an input part 1a is turned on to conduct its output-side transistor TR, grounding the common return line of photocouplers 51, 52-. Consequently, signal outputs of the photocouplers 51, 52- of the input part 1a are fetched in an input port 9 through a data bus 3 and photocouplers 71, 72- of the controller 2. For example, when (n) lines, e.g. n/2 lines each are assigned for address buses 4X and 4Y, (n/2)<2> are specified. |
