Servo processor code evaluation using a virtual disc drive

An apparatus for evaluating programming used by a programmable processor device in a disc drive to carry out servo control of a head with respect to a rotatable disc, the programming comprising a series of instructions executable by the programmable processor device, the apparatus comprising:

• a computer having a computer memory;
• processor emulation software stored in the computer memory configured to simulate execution of the series of instructions by the programmable processor device, wherein the processor emulation software outputs current command signals indicative of current to be applied to an actuator motor used to control head position in response to position inputs indicative of head position;
• plant simulation software stored in the computer memory and configured to generate a dynamic model of electrical and mechanical portions of the disc drive including the head, the disc and the actuator motor, wherein the plant simulation software outputs head position signals indicative of head position in response to the current command signals;
• and
• a dynamic linking program configured to transfer the current command signals from the processor emulation software to the plant simulation software and to transfer the head position signals from the plant simulation software to the processor emulation software, wherein the computer is configured to simultaneously execute the processor emulation software, the plant simulation software and the dynamic linking program to evaluate realtime operation of the programming.