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Smart SQUIDs based on double Relaxation Oscillation SQUIDs (DROS) and a superconducting up-down counter have been developed. DROS and counter form a flux locked loop on one single chip. The DROS output consists of a series of pulses that controls the two up and down write gates of the counter. The pulsed output structure of the DROS constitutes the internal clock for this single-chip device. Several prototypes were built with a clock frequency of 100 MHz, a linear operation flux range of about 2.5 /spl Phi//sub 0/, and a white noise level of 6.5 /spl mu//spl Phi//sub 0///spl radic/Hz. The smart SQUID is in principle a promising device for application in multichannel SQUID systems.