S875WP1-E TPS
Functional Architecture
Revision 4.0
17
3.2.4
Real-Time Clock, CMOS SRAM, and Battery
The real-time clock provides a time-of-day clock and a multi-century calendar with alarm
features. 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 (CR2032) 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 standby current from the power supply extends the life of
the battery. The clock is accurate to
±
13 minutes/year at 25 ºC 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, custom defaults, if previously saved, will be loaded into CMOS
RAM at power-on.
3.2.5
Intel 82802AC 8 Megabit Firmware Hub (FWH)
The FWH provides the following:
•
System BIOS program
•
Logic that enables protection for storing and updating of platform information