| 摘要 |
PURPOSE:To rewrite only a specified bit among plural bits temporally stored to attain rewriting by connecting a capacitor for temporally storing to each data terminal of an RAM. CONSTITUTION:Prescribed address and writing content changing address are applied to the address input terminals A0-A9 of the RAM1 and the address input terminals A10-A12 of a decoder 2 respectively. The stored content of the address appeares to the data terminals of the RAM1 and logic 1 or 0 stored in capacitors 4-0-4-7 corresponding to respective addresses. A write pulse is applied to a terminal T1 and internal impedance observed from the data terminal of the RAM1 is increased. In the decoder 2, only a buffer corresponding to a required bit is turned on among buffers 5-0-5-7, so that only the corresponding capacitor is rewritten by a write data input applied from a terminal T2. When the impression of write pulse is released, the contents of the capacitors 4-0-4-7 are written in the RAM1 again. |
