Recent developments of electronic neural nets in North America

We present a survey of recent electronic implementations of neural nets in the US and Canada with an emphasis on integrated circuits. Well over 50 different circuits were built during the last two years, representing a remarkable variety of designs. They range from digital emulators to fully analog CMOS networks operating in the subthreshold region. A majority of these circutis, over 40 designs, use analog computation to some extent. Several neural net chips are now commercially available, and many companies are working on the development of products for an introduction in the near future.Most of the neural net circuits have been built in standard CMOS technology, except for a few designs in CCD technology. EEPROM cells are investigated by several researchers for building compact, analog storage elements for the weights.While a large number of circuits have been built, there are still only few reports of applications of any of these chips to large, real-world problems. In fact, system integration and applications with neural net chips are just beginning to be explored. We describe some experiences gained with applications of analog neural net chips to machine vision from our laboratory.