Abstract: Process control apparatus for reading the condition of a selected variable and for generating a next instruction to be implemented based on the observed condition of the selected variable. The next instruction is that of reading one of two possible instructions, one of which causes the state of an output variable to be read and/or set and the other calls for reading the value of another selected input. In this manner, a program cycle is completed so that the values of all output variables can be set and read.

Abstract: A time division multiplex communication system comprised of a plurality of modules, each module being equipped with a space division concentrator and a processor. The modules are interconnected by a control bus and by a plurality of speech busses, the number of speech busses being equal to the maximum number of modules. All busses are connected to each equipped module. The control bus is commonly connected to all modules and this bus is, in turn, controlled by a control circuit. In the control circuit, there is a flip-flop for each module for enabling a scanner in the control circuit to set the address of a module seeking use of the control bus. The processor in the module seeking service recognizes its address and transmits its call processing data on the control bus. Each speech bus is comprised of eight wires for parallel PCM bit transmission with time slot interchanging.