Main System Processor

The Main System Processor is responsible for all call processing activities. It may also be responsible for maintenance and diagnostics activities, although some PBX systems are designed with a dedicated processing element for this function. The Main System Processor executes high-level call processing functions based on computer programs stored in system memory, monitors and controls all port-to-port connections, provides status indications to station users, and initiates the operations necessary to implement system features and functions.

The Main System Processor in current PBX systems is typically a 32-bit microprocessor chip from an outside supplier. Intel and Motorola have been the primary suppliers of microprocessor chips used as Main System Processors during the past decade. Several leading PBX systems are currently using Pentium-level microprocessors, although older microprocessors, such as the Intel 386/486 or Motorola 68030/40 chips, are used in many currently marketed systems. Many installed PBXs still operate on older 8-bit or 16-bit microprocessor technology platforms, proof of the long life cycle viability of traditional PBX system common control design.

The main processing element is an important factor for determining PBX call processing power, but it is not the only factor. Software code, call processing system design, and feature/function implementation play important roles in determining the so-called horse-power of a PBX system, known as Busy Hour Call (BHC) capacity (see below). The feature/function capabilities of a PBX system are also relatively independent of the main processor element because the generic software feature/function program in many current PBX systems is processor independent. It must be emphasized that using the latest generation microprocessor chip does not automatically guarantee a PBX system high call processing capacity or advanced feature/function provisioning.