ABSTRACT
To achieve a high data acquisition rate, any on-line data handling and computation had to be as simple as possible. An integer form of data was used to speed up the calculation. Since the original data from the A / D and D / A converters had no higher resolution than 16 bits, a large part of the simple calculations could be done in an
integer mode. However, there was still some need for floating point manipulation such as in the PID feedback calculation, and in displaying the x - y plot of AVmin (or topography-related offset voltage). Furthermore, parameters such as the setpoint of A Vmax, the range of the z-driving waveform, and the PID parameters were all floating point numbers set by the user.
