Patent ID: 7489571

Claim:
A semiconductor device for outputting data read from a read only storage device, comprising: a read only storage device including memory cells; an address signal line for transmitting an address signal to each read only storage device, said address signal indicating an address of memory cells storing data to be read; and a switching device to which said address signal is inputted, wherein said switching device comprises; an address storage circuit for storing address information of a defective memory cell of said read only storage devices and for detecting whether or not memory cells storing data selected by an address signal includes a defective memory cell; a bit storage circuit for storing bit information indicating which bit of data stored in memory cells including a defective memory cell is defective, and for outputting a controlling signal; and a switching circuit for inputting the controlling signal and data outputted from a read only storage device which is selected by an address signal and for outputting said data from said read only storage device, said switching circuit inverting a defective bit of said data outputted from said read only storage device in response to receipt of the controlling signal from said bit storage circuit and outputting data whose defective bit is inverted instead of the data outputted from said read only storage device.