| 摘要 |
<p>PURPOSE:To enable to double the capacity of a mask ROM without increasing the number of input and output terminal pins, by controlling the operation of an output circuit through the combination of address signals. CONSTITUTION:The operation of an output circuit 4 of ROM including an address recorder 2 and memory matrix 3 and said circuit 4 is controlled with the combination of the predetermined address signals. For example, a chip selection/non-selection circuit 5 is constituted of AND gates A, and when all address inputs A0-A13 are at ''1'' only, the signal ''1'' is outputted. The output buffer 4 makes the output a floating state with this signal, and this ROM matrix 3 is made to a non-selection state.</p> |
