CMOS (complementary metal-oxide-semiconductor) memory holds important data such as date, time, hardware configuration information, auxiliary setup information, boot settings, hibernation information, etc.
On a real Mac, non-volatile RAM (NVRAM) is used for this instead. Just like CMOS, NVRAM is also powered by a small battery, which allows it to retain its data when the system power is off.
When running macOS on Wintel systems, it can sometimes trigger a CMOS-reset on some BIOSes/Firmwares when shutting down or restarting the system.
You can use one of the following fixes to resolve the issue:
- CMOS Reset Fix – For fixing CMOS resets triggered by macOS after shutting down or rebooting.
- Emulating CMOS Memory – For fixing conflicts between
AppleRTCand the BIOS/UEFI Firmware. Can be helpful when trying to fix hibernation.