Flash memory for improving write access time

1. A flash memory comprising:

a flash memory cell array including a plurality of blocks;

a page buffer including a plurality of pages, wherein said page buffer temporarily stores therein write data received from an external system;

a comparator circuit executing pre-verification through comparing data stored in said page buffer with data stored in addressed one of said plurality of blocks;

a verify flag buffer storing therein a plurality of verify flags respectively associated with said plurality of pages, wherein each of said plurality of verify flags is switched in response to update of associated one of said plurality of pages, and

wherein said comparator circuit executes pre-verification with respect to one of said pages, said one being associated with unswitched one of said verify flags, while skipping pre-verification with respect to another of said pages associated with said switched one of said verify flags.

2. The flash memory according to claim 1 , further comprising a write history flag buffer,

wherein each of said pages within said page buffer includes a plurality of data sectors,

wherein said write history flag buffer stores therein a plurality of write history flags respectively associated with plurality of said data sectors, each of said plurality of write history flags being switched in response to rewrite of associated one of said plurality of pages, and

wherein said comparator circuit executes pre-verification with respect to one of said data sectors associated with unswitched one of write history flags, while skipping pre-verification with respect to another of said data sectors associated with said switched one of said write history flags.

3. The flash memory according to claim 1 , wherein said page buffer, and said write history buffer are integrated in the same memory cell array.

4. A method of operating a flash memory which includes a flash memory cell array having a plurality of blocks, a page buffer including a plurality of pages, and a verify flag buffer storing therein a plurality of verify flags respectively associated with said pages, said method comprising:

storing write data into said page buffer including a plurality of pages;

switching one(s) of said plurality of verify flags in response to update of associated one(s) of said plurality of pages during said storing; and

executing pre-verification through comparing data within said page buffer with data stored in addressed one of said plurality of blocks, wherein said executing pre-verification includes:

executing pre-verification with respect to one of said pages, said one being associated with unswitched one of said plurality of verify flags, and

skipping pre-verification with respect to another of said pages associated with said switched one of said verify flags.

5. The method according to claim 4 , wherein each of said pages includes a plurality of data sectors, and said flash memory further includes a write history flag buffer storing therein a plurality of write history flags respectively associated with said data sectors,

wherein said method further comprising:

switching one(s) of said plurality of write history flags in response to update of associated one(s) of said plurality of data sectors during said storing, and

wherein said executing pre-verification with respect to said one of said pages includes:

executing pre-verification with respect to one of said data sectors associated with unswitched one of said plurality of write history flags,

skipping pre-verification with respect to another of said data sectors associated with said switched one of said write history flags.