As far as I know, no version of format (DOS 6.22, DOS 7(Win98) or even WIN XP) asks that exact question when formatting a disk or any media...on XP, I seem to recall it's more like "Insert new disk for drive A: and press ENTER when ready..."
And there is no "yes/no" bypass command line switch on any of the above mentioned format versions I know of...
Regardless, you can always create an "answer file" with any parameter(s) you need to answer back to any command line program waiting for keyboard input...
Just create a text file and put the proper answer, a Y in your case on the first line, then hit CR. Save the text file and in your batch file use standard redirection symbol < to redirect input from the answer file to the command line instead of from the keyboard....
example:
batch file might look like this: (DOS 6.22 example)
@echo off
format a: /u /s < answer.txt
<EOF>
answer.txt looks like this:
Y<CR>
<EOF>
Obviously, <CR> just means to hit <Enter> key, not type in <CR> literally.
And <EOF> is the invisible end of file marker placed automatically by the editor program.
End result will be the diskette in A: gets unconditionally formatted, system files are transferred so it's a bootable diskette, and you didn't even see the "Do you want to continue" prompt....
Hope this helps...
Jim