SEMICONDUCTOR INTEGRATED CIRCUIT

摘要

A semiconductor integrated circuit includes a central processing unit and a rewritable nonvolatile memory area disposed in an address space of the central processing unit. The nonvolatile memory area includes first and second nonvolatile memory areas for storing information by utilizing a difference between threshold voltages. The first nonvolatile memory area is so constructed as to have a larger maximum change of the threshold voltage used for information storage than the second nonvolatile memory area. The larger the maximum change of the threshold voltage used for information storage is, the greater the stress on the memory cells due to rewriting of information stored therein is. This is disadvantageous in terms of assurance of the number of rewritings. However, the reading current is larger so that the rate of reading the stored information can be raised. For the first nonvolatile memory area, a priority can be given to raising of the rate of reading the stored information, while for the second nonvolatile memory area, a priority can be given to the assurance of a greater number of rewritings of the stored information.