Main System Memory | Legacy PBX

The main system memory component of the common control complex consists of several types of memory databases:

1. Generic program

2. Operating memory

3. Customer database

The generic program stores the main call processing program consisting of all operating instructions, provides the main processor element with necessary intelligence to perform the tasks required by the system, and executes continuous diagnostics, system measurements, and fault isolation routines. The generic program also includes all feature and function software codes in support of station- or system-initiated call processing features and functions, including the standard feature set and optional software packages.

The operating memory is also known as the working memory because it stores all data and information related to the real-time operating conditions of the PBX system, including port circuit status, switch network status (time/talk slot availability and usage), and status of activated features and related data.

The customer database memory contains all data and information related to station user profiles, terminal devices, and the system configuration. Customer database information includes customer programmed information such as class of service and restriction assignments; hunt, trunk, and call coverage group assignments; call routes and routing patterns; system dial plan; terminal button assignments; and system access passwords.

There is no standard PBX system memory storage supporting the three basic memory databases. Some PBX systems use a single memory storage element that is partitioned. Some PBX systems dedicate a memory storage element to each memory database or segment the generic program from the operating/customer database memory storage element. PBX systems typically use dynamic random access memory (RAM) for main memory storage. Electronic programmable read only memory (EPROM) might be used by older systems still in operation. Flash ROM is sometimes used in small systems to simplify customer database upgrades and shorten reboot time. Generic programs in small PBX system models typically require at least 24 Mbytes of RAM storage; very large models may require up to 256 Mbytes of RAM. Most PBX systems fall within this memory storage range.

A floppy disk drive unit is typically used to load resident software programs into the mass storage unit. Most current generation PBX systems use hard drives embedded on printed circuit boards; older systems used dedicated hard disk drive units. Other storage options are tape drives, Flash ROM, and magneto-optical drives.