Memory with electrically erasable and programmable redundancy

A semiconductor memory device, comprising:

• a first data storage area comprising a first plurality of data storage locations, said first data storage area being capable of receiving data from an exterior environment, retaining said data, and transmitting said data to said exterior environment;
• a second data storage area comprising a second plurality of data storage locations, said second data storage area being capable of receiving data from an exterior environment, retaining said data, and transmitting said data to said exterior environment;
• means for receiving an access request from said exterior environment requesting a transfer of data between a first data storage location in said first data storage area and said exterior environment;
• means, in response to said access request, for accessing a second data storage location in said second data storage area for transfer of data between said second data storage location and said exterior environment when said first data storage location is within a defective portion of said first data storage area, wherein said means for accessing includes a nonvolatile memory portion that will retain any data located therein if power is removed from said semiconductor memory device;
• and
• means for use in testing the retention of said nonvolatile memory portion.

A semiconductor memory device, comprising:

• a main data storage area comprising a first plurality of data storage locations, said first data storage area being capable of receiving data from an exterior environment, retaining said data, and transmitting said data to said exterior environment;
• a redundant data storage area comprising a second plurality of data storage locations, said redundant data storage area being capable of receiving data from an exterior environment, retaining said data, and transmitting said data to said exterior environment;
• means for use in substituting a portion of said redundant data storage area for a defective portion of said main data storage area;
• and
• means for utilizing portions of said redundant data storage area that are not used by said means for use in substituting, for performing data storage functions other than defective portion replacement.