Situation

Make FAT16 USB devices for Cisco Router upgradation.
# FAT/FAT16: Max volume size 4GB, Max file size 2GB.

Solution

1.
Prepare a usb device.

2.
Window+R > type "DISKPART"

DISKPART > list disk

DISKPART > select disk 1

DISKPART > list partition 1

DISKPART > clean

DISKPART > create part primary size=4000

DISKPART > active

3.
Windows + R > type "diskmgmt.msc"

select USB device(4GB) and format it into file system FAT16.