Valid addresses range is from 0000h to 1FBFFh
 and from 20000h to 200FFh. 
 The address range from 1FBFEh to 1FBFFh are
 reserved for 'Write/Erase Lock Byte' and
 'Read Lock Byte'.
 The address range from 1FC00h to 1FFFFh are
 reserved for factory use.
 The address range from 20000h to 200FFh are
 locked only if all blocks are locked.