Peripheral unit selection system having a cascade connection signal line

摘要

A unit address is automatically set in a peripheral unit. A plurality of peripheral units 1 are connected to a CPU unit via a signal line 3. The CPU unit accesses each peripheral unit 1 by individually selecting the peripheral units. The signal line 3 is provided with a first signal line 31 for transmitting an address by bus connection of the peripheral units and a second signal 32 line for transmitting a write command signal by cascade connection of the peripheral units 1. The write command signal is sequentially transmitted in the order in which the peripheral units 1 are connected, and only the peripheral unit 1 that has received the write command signal receives a unit address and retains it in a latch circuit 11a.