The confusion between a ucontroller and a uprocessor may have come about because of the history of the two. A uprocessor was the first to be developed. Recall around the 1970s, the 6800 uprocessor came into existence and the descendant was the ucontroller 6811. The line between the two is drawn when one speaks of "real-time". A uprocessor does not have a very well defined handle of "real-time", but is absolutely excellent in instruction power. A ucontroller is the opposite, the interrupt latency is what gives the uC the advantage to control live hardware. A uprocessor could in no way handle an interrupt like a controller and a controller cannot push through instructions like a processor, regardless of how "modern" the silicon becomes. DSP is a completely different beast in that it is a means of subtracting useful information by performing some form of data manipulation upon an incoming signal. DSP, in its truest sense, can be performed on a modern uprocessor. Usually, if one wishes to look at an analog signal an appropriately chosen A/D will be required to capture the analog input so that the processor can perform analytical expressions (the FFT -> filter some frequencies or perform a graphic equalization -> inverse FFT). A D/A is sometimes not required because the application may not call it out. However, one does not need an A/D to perform the same algorithmic expressions on a set of data that is already "digitized". Hence, saving digitized data can allow for more DSP at a later time when the use of an A/D is not required. A DSP processor is different in the fact that it is more suitable for portable acquisition equipment. DSP processors require less hardware than that of the modern uprocessor. DSP processors are also used more in "real-time" processes, where the data may not be stored. This is not to say that an 8-bit ucontroller could not handle DSP, but generally, the application will determine if the 8-bit ucontroller, the uprocessor, or the DSP processor is suitable. For instance, audio can be done rather well with a uprocessor whereas video may be better suited for an FPGA fitted with DSP.