American Megatrends StorTrends 1312 User Manual page 17

Real-Time Clock, CMOS SRAM, and Battery
The real-time clock is compatible with DS1287 and MCI146818 components. The clock
provides a time-of-day clock and a multicentury calendar with alarm features and century
rollover. The real-time clock supports 256 bytes of battery-backed CMOS SRAM in two
banks that are reserved for BIOS use.
A coin-cell battery powers the real-time clock and CMOS memory. When the computer
is not plugged into a wall socket, the battery has an estimated life of three years. When
the computer is plugged-in, the 3.3 V standby current from the power supply extends the
life of the battery. The clock is accurate to ± 13 minutes/year at 25°C with 3.3 VSB
applied.
The time, date, and CMOS values can be specified in the BIOS Setup program. The
CMOS values can be returned to their defaults by using the BIOS Setup program.
Note: If the battery and AC power fail, standard defaults, not custom defaults, will be
loaded into CMOS RAM at power on.
Onboard I/O
The SMSC LPC47B27X I/O controller provides the following features:
•
low pin count (LPC) interface
•
two 9-pin serial bus connectors, one for RS232 and one for RS422
Chapter 1 Hardware Features 11