Electronic Instrument Systems
Glass cockpits replaced mechanical gauges with a chain of computers and displays, and questions usually test whether you know where each signal is generated and which unit owns which function.
The signal chain
Air data comes from pitot and static probes processed by an air data computer (ADC); attitude, heading and acceleration come from an inertial reference system (IRS) or attitude and heading reference system (AHRS). These feed symbol generators or display management computers, which build the picture sent to the display units. Engine and system parameters pass through data concentrators to the engine indication and crew alerting system (EICAS on Boeing, ECAM on Airbus). The flight management system holds the flight plan and performance data and couples to the autopilot and autothrottle - it does not move the controls itself.
Traps
Questions like to swap units: the ADC does not compute attitude, the IRS does not compute airspeed, and the symbol generator does not store the flight plan. Redundancy is a favourite: displays are usually fed from more than one source and revert automatically when a computer fails, so a blank screen is rarely the correct answer for a single failure. Colour philosophy differs between manufacturers, so learn the general hierarchy rather than one type's exact palette.
Rule of thumb
Red = warning, act immediately; amber = caution, act soon; green = normal; white or cyan = advisory or memo; blue = the action the crew must carry out. If a fault needs no immediate crew action, the indication is amber or advisory, not red.
Worked example
An amber box around an EICAS/ECAM parameter, with an amber value, means the parameter has left its normal range and needs attention, but the aircraft is not in immediate danger - a caution, not a warning.