Abstract: Modularly Structured Digital Communications System having Operations-Oriented and Security-Oriented Components. The switching-oriented, the operations-oriented and the security-oriented components are divided into three structure levels such that apparatus program modules for generating logical switching technology messages, operating technology messages or security technology messages are provided in a line technology task structure. An operations-oriented coordination program module and switching procedure program modules for the control of the operations-oriented and of the switching-oriented information and data flow are provided in an operating technology switching technology coordination task structure. At least one operations-oriented and one security-oriented application program module for sequencing operations-oriented or security-oriented jobs are provided in an application task structure.

Abstract: Modularly Structured Digital Communications system. The multi-tasking operating system of a central system processor control administers a line technology task having device program modules associated with types of terminal equipment and administers a switching technology task having switching procedure program modules independent of the class of terminal equipment and independent of communications service. The line technology task and the switching technology task each have input and output memories operated mailbox like allocated to them. For exchange of messages between the tasks, the multi-tasking operating system have a program bus structure with a transmission protocol defined with universal validity independently of communications service and independently of type of terminal equipment.