Response-table-based virtual responding method and instrument and their   applications in scanning probe microscopes
  We describe a virtual response method and device. It consists of an analog-to-digital converter, a digital-to-analog converter, and a computer and utilizes a searchable response table (RT) pre-stored in the computer to respond to electronic signals. The RT is constructed by measuring the input-output relationship of a real response machine followed by sorting it per input data. To respond, incoming signal is converted to digital data whose position in the RT is then located. The response signal is determined by localized numerical calculation around that position. This method has many advantages: cheap, fast, universal, stable with less noises and errors. 
Jihui Wang, Qingyou Lu, Xuefeng Cui, Bing Wang