In some embodiments, a wearable physiologic monitor comprises a mixed analog and digital application-specific integrated circuit (ASIC) including signal conditioning circuitry, an A/D converter, a real-time clock, and digital control logic. The signal conditioning circuitry includes analog amplification circuitry, analog (continuous-time or switched capacitor) filtering circuitry before the A/D converter, and in some embodiments digital (DSP) filtering circuitry after the A/D converter. The monitor includes sensors such as electrocardiogram (ECG) electrodes, accelerometers, and a temperature sensor, some of which may be integrated on the ASIC. The digital control logic receives digital physiologic data sampled at different rates, assembles the data into physiologic data packets, time-stamps at least some of the packets, and periodically stores the packets in a digital memory. The monitor may include a disposable patch including the ASIC, and a reusable, removable digital memory such as flash memory card. Applications include ambulatory monitoring and quantitative titration of care.