An interface device for a data processing system is provided. The interface device comprises first interface circuitry to receive incoming data and second interface circuitry to transmit processed data to a data store for storage. The interface device is provided with processing circuitry to generate the processed data from the incoming data wherein the processing carried out reduces the data in size. The processing circuitry is also responsive to at least one characteristic of the incoming data or the processed data to transmit a notification signal to a data processing component of the data processing system.