Abstract: A modular electroencephalograph (EEG) system comprises a carrier board comprising one or more electrode connectors, one or more power supplies, and one or more analog-to-digital converter (ADC) modules. Each of the ADC modules comprises multiple input channels, input signal routing, at least one instrumentation power supply, configuration switches for the at least one instrumentation power supply and the input signal routing, an ADC, a programmable gain amplifier, and an ADC communications bus. Each of the one or more ADC modules electrically connects to one of the one or more electrode connectors and one of the one or more power supplies of the carrier board. An embedded computer is configured to run a real time operating system (RTOS), wherein each ADC communications bus of the one or more ADC modules is electrically connected to the embedded computer via a serial interface.