The present invention provides an alkali-free glass having a high strain point, a low viscosity and low devitrification, which is easily subjected to float molding and fusion molding. In this manner, processing and memory requirements are optimized. The buffer circuit is operable to store a data set as a buffered data set, and the data processing circuit is operable to repeatedly apply a data processing algorithm to the buffered data set. Embodiments can be used to determine, among other things, whether or not a printer ribbon is installed in a printer without the use of a snap plate. Three such instruments are provided by the invention including a variety of curvilinear and linear tissue-engaging edges and converging surfaces accommodating their use on the irregular contours of numerous soft tissue areas of the human body.