| 摘要 |
PURPOSE:To preclude a malfunction by selecting one interface device among plural devices, deciding and storing the state of the selecting means when the power source is turned on, and selecting the data transfer procedure of the interface device according to the storage contents. CONSTITUTION:A ROM 2 is stored with a system program and transfer processing routines of a serial interface and a two-way parallel interface independently, a RAM 3 is provided with a status area 301, an are 304 for storing condition settings for operating the serial interface, etc., and an interface flag for storing the selection state of an interface is provided to the area 301. An interface which is connected before the power source is turned on is set with a selection key and the state of the selection key is read when the power source is turned on; when the parallel interface is selected, the flag 310 is set to parallel mode and when the serial interface is selected, the flat is set to a serial mode, thereby storing the condition setting in the area 304.
|
