There are two different types of EI modules, one has a fixed sensor position and the module automatically advances and retards ignition timing based on engine RPM. The module computes engine RPMfromthe dwell duration (time)that the sensor "sees" the magnet in the hub during each revolution of the crankshaft.Timing isadvanced in increments at multiple points along the RPM band between about 2000 and 4000 RPM. The more points or steps a module has in it's timing curve the better and smoother the throttle response will be. There areno moving parts, this is the most common version and most modern, not necessarily the best.

Yours, a fixed timing ignition module does no computing, it just throws a spark every time the magnet passes the sensor. The sensor is linked to the throttle linkage and is moved to advance the timing as the throttle is advanced, timing is retarded as the throttle is retarded. Because it's coupled mechanically in this way, the ignition advance is perfectly linear AND it's tune-able if you know what you're doing and have certain needs/desires.