Abstract: A programming system for a programmable controller is improved by providing for automatic retrieval of the execution programs corresponding to application instructions which do not form a part of the basic program instruction set. Application instructions embedded within a sequence program are recognized and their common operation names are displayed on the operator's display. The corresponding execution instructions are retrieved and subsequently combined with the sequence program while the operator monitors the retrieval operation on the display. After the execution instructions have all been copied over into the memory for the sequence program, the application instructions may optionally be rewritten as standard subroutine instructions including the head address of the given set of execution instructions, to avoid the need for a symbol table to interpret between application instruction names and the corresponding head address for the execution instructions.

Abstract: A disk system that can be easily replaced, repaired, and maintained in the field of a factory when subjected to failure and an FA controller using such disk system. The disk system has two disk units. On a front panel of the disk system are an ON/OFF selector button, a copy instruction button, and the like. By operating these buttons, data of a disk unit in operation can be copied to a disk unit replaced after failure. In addition, disk life can be predicted by built-in integrating timers and the like.

Abstract: There is provided by the present invention a mirror disk device, in which specific numbers identical to those written in disks and name of a drive used as for a master disk are recorded in a set-up memory incorporated therein, this data is compared to a specific number written in a disk to determine a master disk or to transfer data to a slave disk. In the mirror disk according to the present invention, ranges of specific numbers are discretely defined without any conflict according to switching positions of a rotary switch. A first specific number is decided within each of the ranges by a random function and then serial numbers subsequent to the first specific number are assigned as specific numbers. With this feature, it is possible to prevent effective data from being lost due to, for instance, instruction miss because of manual operation.