Solution:

1. Format compact flash card first. (Don't add system files of MS-DOS into it) 2. Make a directory named "WinCE". 3. Copy the three files "NK.bin", "VGA.ini" and "WinCE.reg" into the folder "WinCE". 4. If it's necessary, you could make the startup folder and copy "system.ini" which edits for startup operating into it. 5. Copy "Boot.bmp" into root directory. 6. Use FreeDos command "sys.com" to transfer FreeDos system files to compact flash card. 7. Reboot the system via compact flash card to start WinCE.