scope:

GENERAL

This specification states the specific engineering requirements for a solid state interlocking Processor Memory Module ("MM").

A MM forms the total requirement of memory for the main processor of either a Multi Processor Module ("MPM") or a Panel Processor Module ("PPM") in an SSI system.

All components except memory devices shall be soldered directly to the p.c.b. Soldering of jumper links for address or selection is optional.

The module shall meet all the requirements of BR specification 1900 unless otherwise stated.

The module shall be capable of being configured for different applications by means of links which select the type of memory device installed, and the program in a bipolar PROM which determines the address decoding. This allows the module to be used in a Central Interlocking (SSI MPM or SSI PPM) or in a design Workstation Simulation System (DWS MPM or DWS PPM), with either "Standard Memory" which is interchangeable with equivalent configuration of the Mark 1 Memory Module, or "Extended Memory" which makes use of paging to increase the available program and data address space by 50%. Five options are detailed in Appendix 2:

BR1911A-1  SSI MPM Extended Memory

BR1911A-2 DWS MPM Extended Memory

BR1911A-3 SSI PPM Standard Memory (equivalent to BR1911-3)

BR1911A-4 DWS PPM Standard Memory ( equivalent to BR1911-4)

BR1911A-5 SSI MPM Standard Memory (equivalent to BR1911-1)

The front plate shall carry a label, as defined in Section 8 of this specification.