iphone 3GS ios 4.2.1 8c148a jailbreak by redsn0w

• iTunes upgrade to newest
• iPad connect to pc and backup
• download {iPhone2,1_4.2.1_8C148a_Restore.ipsw}
• download {redsn0w.exe version 0.9.6rc8}

other step as ipad-ios-421-8c148-jailbreak-by-redsn0w.html the same