| 摘要 |
<p>PURPOSE:To protect software with simple constitution by destroying a part of the internal circuit when a read request of contents in a preliminarily determined address is inputted. CONSTITUTION:When the preliminarily set address is inputted, a protective circuit control signal 18 from a programmable address decoder 11 goes to the high level, and transistors TRs 23 and 24 are made conductive, and a large current is flowed from a power source 29 to break a fuse 28. Hereafter, only the low level is outputted to a chip select signal 19b independently of type of inputs. Thus, output requests to an output circuit are not transmitted hereafter, and this device loses the function as a ROM.</p> |
