Abstract: A method and apparatus for adjusting the frequency of a piezoelectric crystal oscillator. The effective frequency of the oscillator is adjusted (trimmed) by periodically inhibiting pulses to the divider stage.The pulse inhibit circuit includes a nonvolatile programmable read-only-memory (ROM) to store binary complement information corresponding to the number of oscillator pulses to be suppressed.A counter is periodically preset with the binary complement information and the count advances in response to oscillator pulses. The difference count between the complement number and the counter's maximum count controls the number of pulses periodically suppressed.

Abstract: A method and apparatus for adjusting the frequency of piezoelectric crystal oscillator. The effective frequency of the oscillator is adjusted (trimmed) by periodically inhibiting pulses to the divider stage.The pulse inhibit circuit includes a nonvolatile programmable read-only-memory (ROM) to store binary complement information corresponding to the number of oscillator pulses to be suppressed.A counter is periodically preset with the binary complement information and the count advances in response to oscillator pulses. The difference count between the complement number and the counter's maximum count controls the number of pulses periodically suppressed.During manufacture/assembly of the timepiece, the ROM is programmed to contain the desired complement information.

Abstract: A solid state digital watch and barometric pressure indicator having a sealed quartz crystal and a second unsealed quartz crystal which changes frequency with atmospheric pressure changes. The frequency variation of the unsealed quartz crystal is measured over a selected (interrogation) period and some number proportional to the frequency variation, which is indicative of the magnitude of atmospheric pressure change, is displayed with an appropriate sign to indicate increasing or decreasing atmospheric pressure.