| 摘要 |
PURPOSE:To use memory space efficiently by setting the total number of bits of different kinds of memories which differ in capacity to 2n and varying the address space that a memory cell occupies on a programmable basis when using the different kinds of memories on the same substrate. CONSTITUTION:Two hundreds fifty six bytes of an 8K byte memory 14 of a semiconductor memory device are assigned to a shadow RAM 14a and 7936 bytes are assigned to a normal RAM 14b. In this case, a backup is assigned only from the start address and the flexibility of constitution is deficient. For example, when a stack area backup is mode, there is a backup preferably in the intermediate area of the memory. For the purpose, scramblers 150-1513 for address scrambling are provided. Those circuits are used and an external address input Ai is inverted freely or not inverted into an input Ai based on a program value in a storage element.
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