SETTING OF ADDITIONAL SUBSTRATE CONFIRMING DEVICE

PURPOSE:To easily confirm the erroneous setting of a set switch by providing a gate which inputs respective signal of a decoder line and a memory and I/O selecting line corresponding to each additional substrate, and setting the output of each gate as the set switch confirming signal of each additional substrate. CONSTITUTION:The output of the gates provided corresponding to the additional substrates 17-1 to 17-n, respectively are set as the confirming signals of the set switches 4-1 to 4-n of the additional substrates 17-1 to 17-n. Therefore, it follows that a LED 13 is lit one after another sequentially in a normal operation by, for example, lighting the LED 13 by the set switch confirming signal and making access to the additional substrates 17-1 to 17-n one after another at the time of starting up a main substrate 16. However, two or more LEDs are lit simultaneously by the erroneous setting of the set switches 4-1 to 4-n. In such a way, it is possible to easily confirm the erroneous setting.