Abstract: An RCA microboard computer is used as the controller for a new instrument package for marine heat flow.The use of the microprocessor allows incorporation of several novel features that lead to the capability for real-time measurement of heat flow.The design is based on the violin-bow type configuration with 7.5m of penetration and fourteen thermistors.An overall resolution of better than ±0.5mK over a range of 20K is achieved by employing a 16 bit A/D converter with the processor making zero offset and drift measurements and applying them to the data.Sixteen such sequential calculations are performed for each thermistor every 3s to obtain a resultant value.The data are output through the serial part of the microcomputer and a standard telephone modem circuit to a hydrophone for acoustic telemetry to the ship.The digital data are received by the ship's transducers,demodulated and entered to a personal computer.The real-time display of the functioning of the sea-floorcapkage alloows the operator to monitor the progress and validity of each measurement.The shipboard micro then calculates the gradient and conductivity for the site.In sea trials in theLabrador Sea,in water depths >4000m an error rate of about 1:10,000 was noted for the acoustic link.