Circuit for testing digital lines

A digital test card for testing the quality of a digital system in a central office system, said digital system includes a digital line card connected to a customer premise equipment by a two-wire digital connection, said digital test card comprising:

• a line interface means for providing a full duplex transmission link between said digital test card and said digital system, when said digital test card is testing said customer premises equipment said line interface means operates as a master, when said digital test card is testing said digital line card said line interface means operates as a slave;
• a relay means for connecting said line interface means to said customer premise equipment, int he alternative said relay means connects said line interface means to said digital line card;
• a receive buffer means for buffering data from said line interface means to said central office system;
• a transmit buffer means for buffering data from said central office system to said line interface means;
• a protocol controller means connected to said line interface means, said protocol controller means performs a packet protocol;
• a microprocessor means arranged to control the operations of said digital test card;
• a Read Only Memory (ROM) for storing a boot program used by said microprocessor means;
• a Random Access Memory (RAM) means used by said microprocessor means for storing an operating program and for temporary storage;
• A NonVolatile RAM (NVRAM) means for retention of data when power to said digital test card is removed;
• a Keylock means connected to said microprocessor means, said RAM means, and said NVRAM means, said Keylock means allows said microprocessor means to lock said NVRAM means and to lock individual pages of said RAM means such that said microprocessor means can only read said locked NVRAM means and said locked individual pages of said RAM means;
• a Direct Memory Access (DMA) means connected to said protocol controller means, said RAM means, and said microprocessor means, said DMA means arranged to transfer data between said protocol controller means and said RAM means independent of said microprocessor means, and;
• a message interface means connected between said microprocessor means and said central office system, said message interface means provides a communication channel between said microprocessor means and a processor in said central office system.

A digital test card for testing the quality of a digital system in a central office system, said digital system includes a digital line card connected to a customer premise equipment by a two-wire digital connection, said digital test card comprising:

• a line interface means for providing a full duplex transmission link between said digital test card and said digital system, when said digital test card is testing said customer premises equipment said line interface means operates as a master, when said digital test card is testing said digital line card said line interface means operates as a slave;
• a relay means for connecting said line interface means to said customer premise equipment, in the alternative said relay means connects said line interface means to said digital line card;
• a receive buffer means connected to said line interface means and said central office system, said receive rubber means buffers data from said line interface means to said central office system, said receive buffer means comprises:
• a receive trap means for trapping receive data from said line interface means and making said trapped receive data available to a processor means, and;
• a receive insert means for inserting data from said processor means, said inserted data is sent to said central office system;
• a transmit buffer means connected to said line interface means and said central office system, said transmit buffer means buffers data from said central office system to said line interface means, said transmit buffer means comprises:
• a transmit trap means for trapping transmit data from said central office system and making said trapped transmit data available to said processor means, and;
• a transmit insert means or inserting data from said processor means, said inserted data is sent to said line interface means;
• a protocol controller means connected to said line interface means, said protocol controller means performs a packet protocol, and;
• a processor means connected to sad protocol controller means, said line interface means, said receive buffer means, said transmit buffer means, and to said central office system, under the direction of said central office system, said processor means controls the operation of said digital test card, and said processor means, through said protocol controller means and said receive buffer means and said transmit buffer means, determines the quality of said digital system.