Abstract: The specification discloses a technique for assisting in the detection of errors and malfunctions in the operation of a digital computer program. The system includes circuitry for connection to the back plane of a digital computer for receiving representations of the program instructions executed by the computer. A memory normally connected to a first in-first out configuration includes a plurality of series connected stages connected to receive the representations, each of the representations normally being sequentially stored in successive ones of the stages and then transferred to the output of the memory and dumped. Mode selection circuitry is operable to interconnect the system in the sentinel, breakpoint or snapshot modes. In the sentinel mode, in response to a computer malfunction, the circuitry is operable to connect the memory output to the memory input to form a first in-last out memory configuration to store the instruction representations in the memory.

Abstract: The specification discloses a system for automatically controlling the connection of telephone calls between a plurality of input telephone trunk lines at a user's dedicated telephone switching facility and a preset number of output telephone trunk lines. Circuitry is provided to receive user authorization code numbers from the user's facility and for comparing the user authorization code numbers with stored code numbers or with a specified algorithymic equation. A dial tone allowing further operation of the system is provided only if the user authorization code numbers match ones of the stored code numbers or is determined valid by the equation. The system receives dialing signals from an input telephone trunk line and in response thereto selects an available one of the output telephone trunk lines according to predetermined efficiency criteria. For example, calls are completed on all flat rate trunk lines (WATS, FX, tie lines and the like) prior to completing calls on variable rate lines (DDD or the like).

Abstract: The specification discloses a system for automatically controlling the connection of inter-city telephone calls between a plurality of input telephone trunk lines at a user's branch exchange and a preset number of output telephone trunk lines. Circuitry is provided to receive user authorization code numbers from the user's facility and for comparing the user authorization code numbers with stored code numbers. A dial tone allowing further operation of the system is provided only if the user authorization code numbers match ones of the stored code numbers. The system receives dialing signals from an input telephone trunk line and in response thereto selects an available one of the output telephone trunk lines according to predetermined efficiency criteria. The system then establishes audio connections between the calling input telephone trunk line and the selected available output telephone trunk line to complete the inter-city call.