scope:

Introduction

Each Flexible Display Subsystem (DIS) "computer unit" comprises two components, one PCbased (the PC) and one VME-based (the host). These communicate with each other via a dedicated Ethernet link. The PC is responsible for the man/machine interface functions, i.e. the displays, the input facilities (keyboard, trackerball and pushbuttons) and the audible alarm. The host is responsible for the other functions which include the train describer, signalling data manipulation, processing the signaller's commands and handling the interfaces to the other subsystems and the interlockings.

The "computer units" are duplicated so there are four Ethernet connections, i.e. connections for host A, PC A, host B and PC B. A data structure identifies these connections and this data structure is created by the IP address compiler.