@tubetime What document is this from?
@cr1901 https://bitsavers.org/pdf/seagate/mfm/ST-251/ST412_Interface_and_Stepper_Motor_Drive_Microcode_Class_19871202.pdf
@cr1901 https://bitsavers.org/pdf/seagate/mfm/ST-251/ST412_Interface_and_Stepper_Motor_Drive_Microcode_Class_19871202.pdf