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PRODUCT MANUAL EPX-C380
65
BIOS SETTINGS STORAGE OPTIONS
JP4 - EEPROM
EEPROM Enable
CMOS Register Reset
1-2
SPI BIOS Write Protect
3-4
SPI BIOS Program Enable
5-6
CMOS EEPROM Enable
7-8
CMOS EEPROM Disable
7 8
JP4
2 4 6 8
□ □ □ □
□ □ □ □
1 3 5 7
CMOS Storage Locations
The EPX-C380’s BIOS configuration is stored in three (3) locations:
(1) CMOS RAM (nonvolatile if battery backed)
(2) EEPROM (nonvolatile storage for user defaults)
(3) FLASH PROM (nonvolatile storage for factory defaults)
Saving the CMOS Configuration
The Real-Time Clock and the CMOS RAM settings can be maintained by an optional battery when the board is powered
off. A battery is always required to maintain time and date functions when the board is powered off.
The EEPROM feature allows the user to save CMOS configuration settings to nonvolatile storage that does not require
a battery. This feature can be enabled/disabled using
JP4
. When enabled, the user’s CMOS settings can be saved to
EEPROM from the BIOS utility’s Main Menu. If the board is powered off with no battery, the user’s CMOS settings will
be restored from EEPROM but time and date information will be lost and returned to default values.
At system boot, the BIOS first performs a checksum validation on the contents of the CMOS RAM. Invalid checksums
usually occur due to a low or disabled battery. If the checksum is valid, the system boots using values stored in CMOS
RAM. If a checksum error occurs, the BIOS attempts to load CMOS values from the EEPROM.
After a checksum validation, the BIOS configuration is loaded from the EEPROM and the boot process continues. If the
EEPROM is disabled or the contents of the EEPROM fail the checksum validation, the system loads the factory default
settings from the FLASH PROM and continues the boot sequence.
For applications where the battery is present, CMOS settings should be saved to both the CMOS RAM and to the
EEPROM so the system can continue to function without user interaction.
Resetting CMOS to EEPROM defaults
If a battery is present, you can reset the CMOS RAM to the values stored in EEPROM by turning the system off and
removing the external battery. Replace the battery and reboot. When power is applied to the board, the system will boot
with the CMOS settings that were stored in EEPROM.
Preliminary
