Earlier Research Processor Implementations at UCSF, 1975-1981


UCSF's General Purpose Non-Real-Time Speech Processor/Stimulator System ~1975-1979

UCSF's Real-Time, Analog, 4-Channel Processor

*  In this investigators opinion, it is quite possible that the rivalry between the UCSF and the House Institute surgical staff was at least partially responsible for the many extra tasks that the engineering group was assigned.

** It should be noted that almost all early multichannel analog systems used unisolated, voltage-controlled stimulators.  To create a truly multi-channel system required that each channel's stimulator be electrically isolated from the other channels.  It should be noted that the electrode contact impedances were far larger than the tissue and perilymph impedances in multichannel implants (see //TBD).  As a consequence, defining such systems using unisolated channels as "multichannel" is questionable at best.  In contrast, Don Eddington's real-time multichannel analog system did use channel-isolated, current-controlled stimulators -- as did UCSF's 8-channel non-real-time speech processing laboratory system. UCSF's portable, take-home device had isolated channels, but used voltage drivers. Whereas, UCSF's table-top real-time systems had isolated current sources (as well as isolated voltage sources as an option, for comparison purposes). See pp. 166 of Merzenich, 1983 for a diagram of one commonly-used configuration of UCSF's table-top real-time 4-channel analog processor. An aside:  I remember hearing that Dr. Hall and Dr. James Flanagan from Bell Labs designed and built one or more optically-isolated current sources in the 1960s for cochlear implant research that they had conducted with Blair Simmons.  When I was doing the same thing 10 years later for animal experiments, I certainly felt in good company!