MS-DOS source leaked

Google indexes the MS-DOS 6.0 source code:
http://www.google.com/codesearch?q=show:WtWZkLcWeso:LqnnKA42GyA&sa=N&ct=rdp&cs_p=http://center.cie.hallym.ac.kr/~yuko/cgi-bin/ez2000/system/db/linux/upload/45/1070214716/MS-DOS.6.0.Source.Code.zip

Since the original file is 404, we win it with a mirror:
http://www.nurs.or.jp.nyud.net:8080/~nnn/MS-DOS.6.0.Source.Code.zip

I believe abort meant terminate process; retry meant retry read operation, and fail means ok, pretend we've readed even though we haven't. Same goes for other operations.