Electrically erasable non-volatile semiconductor memory device for selective use in boot block type or normal type flash memory devices

Abstract

An electrically erasable non-volatile semiconductor memory device has a memory cell array, a first erase unit, a second erase unit, and an operation mode establish unit. The erasing operation of the second erase unit is independently carried out of the erasing operation of the first erase unit. When a first operation mode is established by the operation mode establish unit, the second erase unit is inactivated, and the erasing operation of the memory cell array is only carried out by the first erase unit. On the other hand, when a second operation mode is established by the operation mode establish unit, the erasing operation of the first erase unit for a part of the memory cell array is disable, and the second erase unit is activated and the erasing operation for the part of the memory cell array is carried out by the second erase unit. Therefore, the change between a boot block type flash memory and normal type flash memory can be realized only by changing an establish value of the operation mode establish unit. Consequently, when developing both boot block type flash memory and normal type flash memory, these two types of flash memories can be obtained by using the same chip or by carrying out only minimum changes, so that the developing processes can be greatly decreased.

Dependencies are inferred from the claim text.