| 摘要 |
PURPOSE:To increase storage capacity without increasing the number of address signal input terminals by optionally determining a base address by means of an address data supplied to a register, and selecting, a specified memory cell from a memory array of prescribed bit words by means of an external address signal having the number of bits equal or less than that of the said address data. CONSTITUTION:The specific memory cell is able to be selected within the extent of 256 bit words selectable by means of an 8-bit address signal A0-A7 with the reference of the base address corresponding to a 12-bit address data Da0-Da11. Therefore, the desired memory cell can be selected throughout the entire memory array MA depending on how the base address Abase is set. For the said selection, the external address signal A0-A7 supplied from the address signal input terminal suffices with only 8 bits. As a result, four pieces of address input terminals can be eliminated compared to the case where a 12-bit address signal normally necessary for selecting from a memory array of 4k bit words is directly supplied from the address signal input terminal.
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