ISDN audiovisual teleservices interface subsystem

An interface subsystem adapted for exchanging digital audiovisual information using digital telecommunications, said interface subsystem also exchanging video and audio data with a host digital computer, said interface subsystem comprising:

• a first digital telecommunications interface circuit for exchanging digital audiovisual information with a first digital telecommunications access;
• a host computer interface circuit for exchanging video and audio data with the host digital computer;
• a random access memory for storing digital audiovisual information and video and audio data received from said interface circuits, said random access memory containing a plurality of sort buffers, each addressable location in said sort buffers holding at least one octet of audiovisual information received from the digital telecommunications access, the octets while present in said sort buffers being scanned to locate a frame alignment signal ("FAS") embedded therein;
• a programmable digital signal processing circuit coupled to said interface circuits and to said random access memory for controlling the operation of said interface circuits, for exchanging digital audiovisual information with said digital telecommunications interface circuit, for exchanging video and audio data with the host computer interface circuit, and for processing digital audiovisual information, and video and audio data.