TDX-10: software structure and implementation

A description is given of the structure and the implementation of the TDX-10 software, which is a large-scale electronic switching system with distributed control architecture. The system structure is layered into three levels, a system, a subsystem, and a block. A system, the top level, is divided into many subsystems, each devoted to a specific function. Each subsystem is broken down into many building blocks which consist of several program files. As a basic loading unit in a processor, an execution module is generated by compiling files for a block or for a few blocks. A function could be simply inserted/deleted into/from an existing system by just adding/deleting its relating blocks in the system. Most peripheral processor (PP)-level programs, written in assembly or C-language, are combined with hardware units in the block for the easy maintenance of a system/block with a concept of a virtual machine