Smart verify for multi-state memories

A method of performing a programming operation on a plurality of multi-state data storage elements, comprising:

• performing a programming operation to incrementally move the storage elements from a first data state sequentially through a plurality of second data states;
• verifying the result of the preceding programming operation for a subset of one or more target values from a set of target values each corresponding to a respective second data state;
• subsequently re-establishing said subset of one or more of said target values for a subsequent verify operation based on the result of the preceding verifying, comprising determining whether to include a target value not in the subset of the preceding verifying;
• and
• subsequently repeating the performing a programming operation and the verifying using said re-established subset of target values.

A memory comprising:

• a plurality of multi-state storage elements;
• programming circuitry connectable to the storage units to perform a program operation whereby the state of storage elements can be changed;
• sensing circuitry connectable to the storage elements to determine the value of a parameter indicative of the state of the storage elements;
• comparison circuitry connected to the sensing circuitry for performing a program verify operation using target values for said parameter corresponding to a subset of the multi-state levels;
• and
• logic circuitry connected to the comparison circuitry, wherein adding of one or more multi-state levels to the subset of the multi-state levels that are used in the program verify operation is determined based on the results of the preceding program verify operation.