READ-ONLY SEMICONDUCTOR MEMORY

摘要

PURPOSE:To obtain a memory which inhibits a rewriting when necessary by inhibiting the rewriting for the contents which can rewrite the memory contents any number of times when necessary and are wanted to fix finally. CONSTITUTION:If the programmed contents have an error, the programming is carried out again erasion of data through irradiation of ultraviolet rays or an electrical operation. When it is desired that the programmed and corrected contents are finally fixed, the voltage is impressed between power supply terminals 11 and 12 so as to give the sequential bias to a diode 15. Thus a large current is supplied to a breaking circuit 14, and the circuit 14 is cut off. Thus high voltage VPP is not supplied to a program circuit although the voltage VPP is impressed to the terminal 11. As a result, only read-out of data is carried out. In a data writing mode the read-only voltage VCC is supplied to a route to which the voltage VPP is supplied via a diode 15. Thus a data reading circuit is obtained.