Method of writing, erasing, and controlling memory for memory device

A method of erasing data in a memory device with a memory area having a plurality of blocks, the memory device erasing data by the unit of one block, the method comprising:

• providing a flag for each of the blocks, the flag indicating if there is data written in a corresponding one of the blocks;
• and
• erasing data written in one of the blocks when the flag indicates that there is data written in the one of the blocks.

A method of erasing data in a memory device with a memory area having a plurality of blocks, the memory device erasing data by the unit of one block, the method comprising:

• marking one block with an executing flag which indicates if a process of erasing all memory space is underway;
• and
• erasing all memory space, with the one block being a last one to erase.

A method of managing a memory device having a memory area and a controller for controlling data writing in the memory area, the method comprising:

• sending to the controller a size of data to be written into the memory area;
• and
• estimating, by using the controller, a length of time to be required for writing the data into the memory area on a basis of the size of the data and conditions of the memory area.

A method of checking a flag recorded on a memory area which has a possibility that part of the memory area can become unable to be erased, the method comprising:

• providing a plurality of bits in the memory area for one function of the flag;
• and
• checking a status of the flag by using a logical product of the plurality of bits.

A method of managing a memory device having a plurality of chips, each provided with a plurality of blocks, a free block of the blocks being used for writing new data, a block having old data replaced by the new data being erased by a unit of one block, the method comprising writing the new data into one of the chips, wherein one of the chips used for writing the new data is always the same for a given new data.