Buffer Coding for Asymmetric Multi-Level Memory
Certain storage media such as flash memories use write-asymmetric, multi-level storage elements. In such media, data is stored in a multi-level memory cell the contents of which can only be increased, or reset. The reset operation is expensive and should be delayed as much as possible. Mathematically, they consider the problem of writing a binary sequence into write asymmetric q-ary cells, while recording the last r bits written. The authors want to maximize t, the number of possible writes, before a reset is needed. They introduce the term Buffer Code, to describe the solution to this problem. A buffer code is a code that remembers the r most recent values of a variable.