set input_file=input.bin
set output_prefix=output_
set chunk_size=256
set /a chunk_count=4
for /l %%i in (0,1,%chunk_count%) do (
set /a offset=%%i*chunk_size
set output_file=!output_prefix!%%i.bin
echo Splitting !input_file! to !output_file! from offset !offset!
dd if=!input_file! of=!output_file! bs=!chunk_size! skip=%%i count=1
)