Microcomputer comprising flash EEPROM

Claim 1

A microcomputer comprising: a programmable memory having a plurality of blocks, the blocks being divided into first blocks which store a first program and a second block which stores a second program; a circuit for supplying address signals which indicates the block to be erased; a circuit for supplying a block erasing bit which represents whether or not said second program is to be erased; a circuit for erasing the selected block; wherein said block erasing bit has a first state when said second program may be erased, while said erasing block bit has a second state when said second program is not to be erased; and said selecting circuit operable in a first mode when said block erasing bit is in the first state for selecting any one of said first and second blocks for erasing only said selected block; and said selecting circuit operable in a second mode when said block erasing bit is in the second state for selecting one of (1) one of said first blocks and (2) a plurality of said first blocks for simultaneously erasing said selected plurality of first blocks.