Variant operation sequences for multibit memory

摘要

A multiple-bit-per-cell, page mode memory comprises a plurality of physical pages, each physical page having N addressable pages p(n). Logic implements a plurality of selectable program operations to program an addressed page. Logic select one of the plurality of selectable program operations to program an addressed page in the particular physical page using a signal that indicates a logical status of another addressable page in the particular physical page. The logical status can indicate whether the other addressable page contains invalid data. The first program operation overwrites the other addressable page, and the second program operation preserves the other addressable page. The first program operation can execute more quickly than the second program operation. The logic can also be applied for programming multiple-bit-per-cell memory not configured in a page mode.

主权项

1. A multiple-bit-per-cell memory, comprising:
a memory cell having at least two addressable bits; logic to execute a plurality of selectable program operations to store a program data value for a selected addressable bit of the at least two addressable bits of the memory cell when the memory cell has an initial threshold within a range representing a data value previously stored in an unselected one of the addressable bits, the plurality of selectable program operations including:
a first program operation which establishes a first target threshold within a first range which represents the program data value for the selected addressable bit, and which does not represent any data value for the unselected one of the addressable bits of the memory cell; anda second program operation which establishes a second target threshold within a second range which represents the program data value for the selected addressable bit and the data value previously stored for the unselected one of the addressable bits; and logic to select one of the selectable program operations.