• PC-based oscilloscopes : A new type of "oscilloscope" is emerging that consists of a specialized signal acquisition board (which can be an external USB or Parallel port device, or an internal add-on PCI orISA card). The hardware itself usually consists of an electrical interface providing isolation and automatic gain controls, several high-speed analog-to-digital converters and some buffer memory, or even on-board Digital Signal Processor (DSPs). Depending on the exact hardware configuration, the hardware could be best described as a digitizer, a data logger or as a part of a specialized automatic control system.