This article describes two generations of a novel integrated circuit multi-anode electron detector chip (LEDA512). This chip is designed for usage as an analog ion detector in magnetic mass spectrometers, in combination with a stack of two micro channel plates. The first generation chip is applied in a positive ion mass spectrometer on-board the ESA ROSETTA cometary mission. The detector chip comprises two identical and redundant parts, each consisting in a row of 512 rectangular anodes for electron collection, and in an anode multiplexer followed by a charge amplifier. A second-generation of the chip is scheduled. It will implement additional features, such as: radiation hard MOS transistors and shift registers and improved output drive capabilities.