MEMORY SYSTEM RESTORATION

摘要

Restoration of information in a memory of the type requiring periodic restoration to maintain viability of the information is carried out in a manner dependent on the relative need of memory cells in the memory for restoration. This system includes an array of memory cells in which the stored information must be restored periodically to maintain its viability. Means for accessing the memory cells in the array desirably accomplishes a restoration of a memory cell each time it is accessed. Means for determining a priority list of the memory cells in the array for restoration does so in an order substantially dependent on the relative need of the memory cells for restoration. Means are provided for restoring the memory cells sequentially in the absence of a requested access to the memory array in accordance with the priority list established by the priority list determining means. In this manner, a memory requiring, e.g., 50 percent of its operating time for restoration may be available 90 or even 100 percent of the time a requested access is made.