The AMAC system was the forerunner to the Messenger series of devices. It was both a monitoring and control system that operated over a wide variety of data transport mechanisms, including GSM, MOBITEX, Paknet, PMR, etc. The system comprised of a number of remote monitoring devices, the NT11 or DM2412, each of which had 8 digital inputs, 8 digital outputs, 4 analogue inputs and 2 analogue outputs. The DM2412, specifically designed for radio networks, had an onboard FFSK modem that could transmit data over a radio channel. The NT-11 connected to any external communications device such as a modem, radio PAD, etc. The central host station was built around a PC based touch-screen software application providing facilities much like the current NHDS host terminals.