NR SSI8505G ISSUE 1 PDF

This chapter defines the processes to be followed in programming, checking, and labelling EPROMs for use with SSI, and for the populating of Memory Modules with new or updated program and/or data EPROMs. Introduction

The EPROM programming instructions replace those formerly given in specification BR1990, and shall be used for programming the following:

• EPROMs. These are housed within the sealed carcass of the module concerned, and will only be accessible to the module manufacturer or authorised repairer.

•  Program EPROMs for the Technician's Terminal. Instructions relating to the installation are contained in SSI8506 "MkII Paged Technician's Terminal Installation Manual". ·

• Other signalling applications to which specification BR1990 formerly applied, and any other signalling applications as required by Railtrack.

The EPROMs for use within Memory Modules may contain either fixed programs or geographic data. Programs shall be of the type required for the particular version of CI in use, as defined in SSI8150 "SSI Software Record". Data shall be prepared in accordance with SSI8003 "SSI Data Preparation", and will be unique to each CI.

It is a fundamental requirement that all Vital Programs and Data be stored and handled in a manner such that the integrity of the information is protected against all credible failures of the storage and handling process.

This is achieved by:

• Keeping at least two copies of all programs and data

• Only handling one of these copies at any one time

• Comparisons of the output of every process involving the replication of programs or data against independently maintained verification masters

• Use of checksums to provide further confidence in the validity of stored programs and data.

Similar measures are applied to Non-Vital Programs and Data, although some of the controls required are relaxed. A definition of those Programs and Data classified as Vital or Non-Vital is given in SSI8150 "SSI Software Record".