| 摘要 |
<p>PURPOSE:To enable to obtain a device which performs both program creation and product control by a method wherein a device which neutralizes erasing and rewriting-in functions is added to the semiconductor memory storage which performs electrical erasing and rewriting-in functions, and this enables to convert the above device into an ROM which does not perform erasing and rewriting-in functions. CONSTITUTION:A high level signal is outputted from a power source terminal 5 to the gate 12 of a switch 10 through a fuse 8 and a resistor 9, and the switch 10 is conducted. At this time, a current is run from a power source 6 through a resistor 11, a terminal 13 is turned to a low level, and as a result, a switch 15 is conducted, a switch 14 is brought into a broken status, and the positive or negative high voltage to be applied from a terminal 16 to the gate, the source or the drain of the memory element which is not shown in the diagram, is outputted from a terminal 17. Thus, the writing-in and the erasing can be repeated any number of times under normal conditions, but when the fuse 8 is blown out by applying high voltage on the terminal 5, low voltage is repeatedly applied to the gate 12 of the switch 10, and an ROM function is given to the device.</p> |
