Patent ID: 7602652

Claim:
A non-volatile memory system, comprising: a first group of non-volatile storage elements from a set of non-volatile storage elements that are programmed together, said first group is programmed to a first physical state associated with a first range of threshold voltages, said set of non-volatile storage elements is programmed from lower threshold voltages to higher threshold voltages; a second group of non-volatile storage elements from said set of non-volatile storage elements, said second group is programmed to a second physical state associated with a second range of threshold voltages, said first and second ranges of threshold voltages defining a first margin of a first size between said first physical state and said second physical state, said second range of threshold voltages includes larger threshold voltages than said first range of threshold voltages; and a third group of non-volatile storage elements from said set of non-volatile storage elements, said third group is programmed to a third physical state associated with a third range of threshold voltages, said second and third ranges of threshold voltages defining a second margin between said second physical state and said third physical state of a second size smaller than said first size said third range of threshold voltages includes larger threshold voltages than said second range of threshold voltages.