In a 51-chip, the entire PEROM array and the electrical wipe of the three locking bits are able to combine the correct control signals and need to be kept low at the ALE port input and will last 10 milliseconds.Suppose the chip is in the process of performing a scrub operation, and this is, we need to write all "1" into the code array, and this must be done before any non-empty storage bytes can be programmed repeatedly.