Computerized on-board system for controlling a train or rail vehicle, of the type comprising: - a train control and monitoring system (TCMS) comprising: - a main processor unit for controlling the train; - electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which is capable of providing control data for the train; - remote input/output modules which are capable of relaying data to and from the main processor unit for the outputs/inputs of the train or for the electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which is connected to sub-networks for data transfer; - at least one display unit which is capable of making available the control data of the train provided by the main processor unit and/or by the electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42); and - a main data transfer network to which there are connected the main processor unit, the or each display unit, the remote input/output modules and the electronic control, command and monitoring items of equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which are capable of producing specific data for the control of the train and which are connected to the main data transfer network directly or by means of remote input/output modules, characterized in that the main processor unit or the electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) ensures the implementation of the functionalities comprising the start-up and preparing of the train, the traction and breaking of the train, or the driving in different modes of the train, in that the electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which is capable of producing specific control data for the train comprises at least one of the additional items of equipment from: - electronic equipment for automatic train control, and - video surveillance equipment (CCTV) and in that the display unit is capable of processing the data and displaying, in addition to the data provided by the main processor and the electronic control, command and monitoring equipment, data produced by one of the additional items of equipment (30, 36). - a train control and monitoring system (TCMS) comprising: - a main processor unit for controlling the train; - electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which is capable of providing control data for the train; - a main processor unit for controlling the train; - electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which is capable of providing control data for the train; - remote input/output modules which are capable of relaying data to and from the main processor unit for the outputs/inputs of the train or for the electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which is connected to sub-networks for data transfer; - at least one display unit which is capable of making available the control data of the train provided by the main processor unit and/or by the electronic control, command and monitoring equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42); and - a main data transfer network to which there are connected the main processor unit, the or each display unit, the remote input/output modules and the electronic control, command and monitoring items of equipment (22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42) which are capable of producing specific data for the control of the train and which are connected to the main data transfer network directly or by means of remote input/output modules, - electronic equipment for automatic train control, and - video surveillance equipment (CCTV) and