A method to exchange data in a shared memory system includes the use of a buffer in communication with a producer processor and a consumer processor. The server system is coupled to a centralized database and at least one client system. The method and apparatus of the present invention can further accommodate input delays and output delays associated with the linear time invariant system with delays. Between the excitation coil and GMR sensor is a highly permeable flux focusing lens which magnetically separates the GMR sensor and excitation coil and produces high flux density at the outer edge of the GMR sensor. Accordingly, the loss of a top surface of the trench oxide film can be minimized and a bit line can be formed to have a uniform height.