| 摘要 |
PURPOSE: A memory device is provided to full up a rectangular by using an address multiplexing method and to use the same hardware logic when decoding a lower and an upper address so that it can reduce a cost of implementing a hardware and a memory cycle time. CONSTITUTION: The device comprises a memory array(115), an X decoder(150), a Y decoder(130), an X selector(160), and a Y selector(140). The X decoder(150) and the Y decoder(130) selects an upper address and a lower address sequentially input, and decodes the addresses. The X selector(160) and the Y selector(140) selects select lines corresponding to a desired band by storing outputs of the X decoder(150) and the Y decoder(130). An L/U select signal is input to the X decoder(150) and the Y decoder(130) for selecting the lower address and the upper address. Upper strobe latch signals are input the X selector(160), the Y selector(140) and the Y decoder(130) for storing the output of the decoder. The X decoder(150) has the same structure with the Y decoder(130). Also, the X selector(160) has the same structure with the Y selector(140). The decoders(150,130) includes four AND gates for decoding the input addresses, and four multiplexers for selecting one among the decoded result on the upper address and the lower address.
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