A snippet from the larger patent....it's quite complicated and thorough

http://www.freepatentsonline.com/6732106.html

When the digital data is sent from the distribution server 1001 , the device access process control means 1019 stores the digital data in the storage media 1022 by controlling the storage media access means 1020 , and at the same time, stores the same digital data in the cache storage means 1019 . Then, when the information regarding the digital data storage location is sent, the media access process control means 1019 stores the digital data that has already been distributed and stored in the cache storage means 1024 in the storage media 1022 , by controlling the storage media access means 1020 .

The storage media 1022 is a semiconductor memory card having the media ID 1023 , which is a unique ID. As shown in FIG. 11 , the storage media 1022 has a secure data area 1101 , which cannot be accessed without an authorization from the storage media access means 1020 , and a data area 1102 which can be accessed without the authorization. The media ID 1023 is stored in the secure data area 1101 .

The storage media access means 1020 is a card adapter that reads and writes data from and in the storage media 1022 . The storage media access means 1020 has the device ID 1021 , which is a unique ID.

In this embodiment, the storage media access means 1020 is attached to the personal computer 103 externally. One or a plurality of storage media access means 1020 can be connected to the personal computer 103 .

Operation of each element will now be explained below, with respect to each operation offered by the digital data distribution system