The Explorer 8240 Digital-Only DVR for Standard, HD, and Multi-Room is now obsolete (past End-of-Life and End-of-Support status).
You can view a listing of available Video offerings that best meet your specific needs
If you want support information for the Explorer 8240 Digital-Only DVR for Standard, HD, and Multi-Room documentation, it may be available through Cisco.com Search or in the Cisco Community