Battery-backed clock – Ampro Corporation 486E User Manual
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Little Board™/486e Technical Manual
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Battery-Backed Clock
An AT-compatible battery-backed real-time clock (with CMOS RAM) is standard on the
Little Board/486e CPU. A 3.6-volt Lithium battery connected to the Utility Connector, J16, can
power the clock. Battery drain for the clock is less than 1 uA. This battery will support the clock for
about 10 years.
Use the Ampro SETUP utility to set the current time and date in the real-time clock, as well as
SETUP information in the CMOS RAM portion of the clock chip (configuration memory).
The contents of the configuration memory are also stored in an onboard EEPROM. The ROM BIOS
reads the EEPROM to get configuration information if the CMOS RAM data is lost. This means
that the board functions without the battery. However, without a battery the real-time clock date
and time will not be correct.