| 摘要 |
<p>PURPOSE: To provide an optional board identification device with simple circuits by using an analog voltage as the identification signal of an optional board, measuring the analog voltage by a voltmeter and decoding the signal. CONSTITUTION: The respective optional boards 4 are provided with a resistor 39, a comparator 5 and an identification circuit as the common circuits of the optional boards in addition to the circuits intrinsic to the optional boards. When only a slot 22 is connected to the optional board 4, a resistance value from a Vcc to ground becomes 4.5R, a voltage on a voltage output line 201 becomes Vcc-Vcc(R/4.5R)=Vcc (7/9), the voltages of the voltage output lines 202, 203 and 204 similarly become Vcc (5/9), Vcc (4/9) and Vcc (2/9) respectively and the voltages are measured by a switch 12 and the voltmeter 13. Since a voltage drop between the voltage output lines 202 and 203 is 1/2 of the other voltage drop, it is recognized that the board is connected only between them.</p> |
