Instantly create a large file in dos:

Use Windows Calculator in Scientific mode to convert a number in bytes to hex. IE: 1 million bytes. Enter 1000000 in the calculator and click on the Hex option to convert it (1 million in hex is F4240.) Pad the result with zeroes at the left until the file size reaches eight digits—000F4240.

Open a dos window:

-run: DEBUG BIGFILE.DAT (ignore the File not found message.)

-Type RCX and press Enter. Debug will display a colon prompt.

-Enter the last four digits of the hex #(4240, in this example).

-Type RBX and press Enter

-Enter the first four digits of the hex #(000F, in our example).

-Enter W for Write .

-Enter Q for Quit.

You’ve just created a 1-million-byte file using Debug.