System including data storage device, and data storage device including first and second memory regions

A system comprising a host device and a data storage device operatively coupled to the host device, the data storage device comprising:

• a non-volatile memory device including a non-volatile memory cell array, the non-volatile memory cell array including a first region and a second region;
• and
• a memory controller configured to receive from the host device a current write command and current write data to be stored in accordance with the current write command, to judge whether a size of the current write data exceeds a reference size, and to execute the current write command such that the current write data is stored according to a judgment result,
• wherein when the current write data exceeds the reference size, the memory controller executes the current write command by controlling the non-volatile memory device such that a first portion of the current write data is stored via a main program operation in which the first portion of the current write data is stored in the second region without storing the first portion of the current write data in the first region, and such that a remaining second portion of the current write data is stored via a buffer program operation in which the second portion of the current write data is stored in the first region operating as a buffer for the second region,
• wherein when the current write data does not exceed the reference size, the memory controller executes the current write command by controlling the non-volatile memory device such that all of the current write data is stored via the buffer program operation in the first region, and
• wherein a number of bits stored per memory cell in the second region is greater than a number of bits stored per memory cell in the first region.