LOW-ORDER PROGRAM SUPERVISORY SYSTEM IN MULTITASK MANAGING PROGRAM

PURPOSE:To prevent chain runaway from occurring by performing an adjacent buffering zone compair check processing to detect the destruction of a stack area by write on a buffering zone, and a normalcy check processing on a stack pointer address at the present time. CONSTITUTION:When data except of '0' is found out as comparison result with data '0', it is probable that the write is performed on the buffering zone and also, the write is performed on another adjacent stack area interposing the buffering zone. A decision processing judges that the probability of the runaway of not only a low-order program, but the low-order program using an adjacent stack area due to the destruction of the stack area exist, and progresses a processing to a system error post-processing. In such a way, a managing program recognizes the low-order program in which the chain runaway occurs by using the low-order program in which runaway occurs by overflowing a supplied area and a destroyed stack area.