PROGRAM DISPLAY DEVICE

PURPOSE:To facilitate debugging by continuously displaying all blocks regarding an element by investigating all programs once a retrieval command is generated with the element number set. CONSTITUTION:A sequence program stored in a sequence memory 11 is written as blocks in a buffer area 22. When the program written in the buffer area 22 regards a specified element, the addresses and instructions of a sequence program which corresponds to the starting address of the buffer area are written. Then, the same block is retrieved successively and if an instruction regarding the element is found, it is written in the buffer area 22 in succession to the last found one. The data in the buffer area 22 obtained by retrieving all of a series of sequence programs are displayes. At this time, an overlap, etc., of an instruction, when found, is displayed.