| 摘要 |
PURPOSE:To provide the memory access system which can hold data even when the power source is turned OFF and also enables fast access. CONSTITUTION:A volatile memory 2 has enough capacity to store the protection data 11 in a nonvolatile memory 1 and a transfer means 3 transfers the protection data 11 to the nonvolatile memory when the power source is turned ON. Then a request to read the protection data is made by a processor or other devices to the volatile memory 2. In a buffer 6 provided so as to speed up writing to the nonvolatile memory 1, data can be written faster than in the nonvolatile memory 1, and alteration data 4 written in the nonvolatile memory 1 can temporarily be stored. A writing means 5 when altering the protection data writes the alteration data 4 in the volatile memory 2 and also writes the data in the nonvolatile memory 1 as well through the buffer 6. Consequently, the protection data 21 in the volatile memory 2 can be accessed fast and when the power source is OFF, the protection data 11 are held in the nonvolatile memory 1. |
