Abstract: A method and system are disclosed for selectively altering the functional characteristics of a data processing system without physical or mechanical manipulation. A data processing system is first manufactured having a predetermined set of functional characteristics. A multibit alterable code which includes a functional characteristic definition is then initially loaded into physically secure, nonvolatile memory within the data processing system, utilizing an existing bus, or a fusible link which may be opened after loading is complete. The functional characteristic definition is loaded from nonvolatile memory into a nonscannable register within a secure portion of a control logic circuit each time power is applied to the data processing system and the definition is then utilized to enable only selected functional characteristics.

Abstract: An object of this invention is to provide a disk player in which a plurality of disks different in diameter are driven, and can be identified with high accuracy. Disclosed is the disk player, a digital signal processing section applies to a CPU a synchronization signal which is raised to high level when the frequency of a detection signal outputted by a laser pickup reaches a predetermined value which permits a data reading operation, and a sense signal which is raised to high level when the frequency of the detection signal is shifted from a predetermined frequency. The CPU operates to rotate a spindle motor, and to brake the latter when the synchronization signal is raised to high level. The CPU further operates to detect a period of time which lapses from the time instant the motor is braked until the sense signal is fallen to low level, and to identify the loaded disk from the period of time thus detected.