1. A program-controlled communication system having a programmable digital computer system that processes information according to instructions stored in function oriented program modules and that derives output information therefrom, said computer having a system memory in which is stored data and the program modules, and said computer having a central processing unit by which the program modules are executable, said central processing unit executing a multi-tasking operating program for controlling the central processing unit, the operating program having an activation identification program controlling the central processing unit to identify each program module which is executable in a process list, the multi-tasking operating program further having a central processing unit allocation program controlling the central processing unit to select a respective program module from the process list and execute the selected program module, comprising: a plurality of program module function groups, each program module function group having a plurality of program modules and each program module function group of the plurality of program module function groups being associated with specifically defined functions; and the central processing unit when executing the central processing unit allocation program having first selector means for selecting program module function groups sequentially according to a sequence table programmed therein, such that each program module function group of the plurality of program module function groups is selected for a predetermined time period; and the central processing unit when executing the central processing unit allocation program having second selector means for selecting for execution in the central processing unit a program module included in the program module function group selected by the first selector means.