#! /bin/sh --
if test "$#" != 1
then cat <<EOF
Usage: $0 nes-file

This script uses dd(1) to remove garbage from the
header of an old-format .NES file, making it a valid
new-format .NES file.

DO NOT RUN THIS ON VALID NEW-FORMAT .NES FILES, IT
WILL *DESTROY THEM*!!!
EOF
exit 1
fi

if mv "$1" "$1".old
then
dd bs=1 if="$1".old of="$1" count=7 2> /dev/null &&
dd bs=1 if=/dev/zero of="$1" count=9 seek=7 2> /dev/null &&
dd bs=1 if="$1".old of="$1" skip=16 seek=16 2> /dev/null &&
rm "$1".old && exit 0
mv "$1".old "$1"
fi
exit 1