Storage device and operation method thereof

An operation method of a storage device comprising:

• selecting a first word line among a plurality of word lines;
• generating a speed information representing a speed characteristic of each of a plurality of memory cells connected to the first word line;
• determining at least one memory cell among the plurality of memory cells that is programmed into a predetermined program state among a plurality of program states;
• determining a first memory cell among the at least one memory cell based on the speed information;
• and
• performing a state-shaping operation to convert a data corresponding to the predetermined program state for the first memory cell into a value corresponding to a program state different from the predetermined program state.

A computing system comprising:

• a host device configured to output a command requesting a program operation of a memory device;
• and
• a memory controller configured to receive, from the memory device, a speed information indicating whether a plurality of memory cells connected to a select word line are fast cells or slow cells;
• determine a target memory cell, among the fast cells, that is to be programmed into a predetermined program state among a plurality of program states;
• and perform, based on the command, a state-shaping operation on a data corresponding to the predetermined program state for the target memory cell.