| 摘要 |
PURPOSE:To normally input and output a serial access memory SAM even if a spare data register is used by electrically connecting the spare data register to data buses and cutting off a fuse corresponding to a data register to be replaced. CONSTITUTION:When a column composed of a pair of bit lines 7a and 7b and a sense amplifier 8a is replaced with a spare column composed of a pair of bit liens 7g and 7h and a sense amplifier 8d in a RAM part, a cutting fuse 9a is cut off. Thus transistors 14a and 14b are conductive, and the spare data register is connected to the data buses a and 5b. However, since serial gates 6a and 6b remain nonconductive, the data register 1a remained isolated from the data buses 5a and 5b. Thus, the data register 1a is replaced with the spare data register 1d.
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