| 摘要 |
PURPOSE:To execute rewriting of data of only optional bits, and to shorten a processing time by dividing a write operation of a memory into two, and writing new data for every bit, or selecting the preservation of contents of the memory. CONSTITUTION:Respective switches SW1-8 of a bit write controlling circuit 13 are connected to an A side or a B side in each bit unit. As a result, it becomes possible that MPU data whose writing is executed at 1 byte unit is written in each bit unit, or the previous data written in an RAM is preserved. A bit mask controlling latch circuit 12 controls whether each switch SW1-SW8 of the bit write controlling circuit 13 is connected to the A side or the B side. Also, the bit mask controlling latch circuit 12 determines whether the data is rewritten for every bit, or the data on the RAM4 is preserved. |
