Instrument Bus: An Electronic System Architecture for Oceanographic Instrumentation.

Abstract : A family of electronic and mechanical components has been developed to streamline the process of designing electronic systems for in-situ oceanographic instrumentation. The basis for the family is a card rack designed to fit into 6-in. I.D. pressure cases, and a companion CMOS computer backplane derived from the IEEE-796 (Multibus) standard. A set of computer boards based on the 80C86 processor was designed and implemented using this architecture. The board set includes the 80C86 CPU, a 64 kbyte memory module, serial and parallel I/O, timebase and counter, and a 16-bit A/D converter. A computer based on this board set consumes 375 mW at 5V while operating with a 5 MHz CPU clock, and 7.5 mW with the CPU clock, and 7.5 mW with the CPU clock in STOP mode. In addition to computers, the card rack design can also be adapted to the implementation of other electronic subsystems, including analog front end, mass storage, and power control systems. This report describes the system architecture, gives electronic and mechanical specifications for the backplane and rack, and documents each of the computer boards designed to date. (Summary portions of this report have appeared in the Proceedings of the IEEE Oceans '86 Symposium.) Keywords: Central processing units; Input output processing; Analog to digital converters.