With a 2 phase stepper motor operating in the full step mode, the exact physical resolution of the motor is reached. For a 200 step motor that means an obtainable resolution of 200 steps per revolution at the motor shaft. The full step position of the rotor is characterized when both phases 1 and 2 are fully powered. In the full step mode there only exist phase patterns with both phases 1 and 2 powered. Never is only one phase powered.
For raising the physical step resolution, power stages can be switched to other operation modes. For example: half step, 1/4 step, 1/8 step ... micro step mode. Some Phytron power stages can be set to resolutions up to 1/512 step.