Here 2 blocks are used for the directory.
First blocks store the FAT and second block Store the Directory.Each entry second block can contain file name, starting block and metadata.
so No of files=4KB/4B = 1024 maximum files are possible.
As shown in diagram each entry in FAT stores the next block address of the same file. so total 256 blocks per file are possible.
The FTA table is created for all files at one place. If disk having only 256 blocks then max file size =256-2=254. But here it can allocate 256 blocks.
so maximum file size should be 256 blocks.