FIG. 6 is a flow chart illustrating an embodiment of a process 600 for decoding a reference bit stream using hard-decision input, which may be performed as an initial, or early, stage of calibration (e.g., as part of block 502 in FIG. 5A or block 512 in FIG. 5B). The process 600 includes reading the reference memory location/page using a default voltage read level. For example, in a 3-read scheme, the default read level may correspond to the intermediate read level. At block 604 it is determined whether the page can be decoded using the default read level to provide hard-decision input. If so, then the process 600 is complete, as the reference page can therefore be correctly decoded. If the page cannot be decoded using hard-decision input, the process 600 includes attempting to decode the page using higher and/or lower voltage read levels, wherein the process 600 terminates upon successful decoding. In certain embodiments, the process 600 loops until the page can be decoded successfully using hard-decision input. Upon completion of the process 600, further calibration steps may be performed, as discussed herein.

Multi-Read Approach—Perform Multi-Read on Reference Data