The standard CMOS configuration screen includes settings for items such as
Date
Time
Floppy disk drive types for drives A: (first floppy disk drive) and B: (second floppy disk drive)
Hard drives connected to the IDE interface
firmware chip
By entering the CMOS setup you are able to change the boot sequence of your computer, enable or disable RAID, and change power-on settings. The CMOS setup also allows you to view and change floppy, hard drive, and optical drive settings, as well as change a number of other hardware configuration options.
Cmos ram.
F2
Most computers have a keystroke (usually esc, del, or F12) that will interrupt the boot sequence when you start your computer. In the past, this would be when the white text flies across the screen displaying memory available, hard disk sizes, etc. This will get you into the BIOS for "cmos setup". CMOS is a type of memory that does not lose its data on power loss. In earlier computers, this is where the boot up configuration was stored; hence the phrase, "setup cmos"
date time change and window starting problem
Josh Rogers page 12 section 4-5
Most likely the small battery inside the case that powers CMOS RAM needs replacing.
No, not all systems use the same method to enter CMOS setup. Some systems allow access to CMOS setup by pressing DEL during start up and others by pressing F2.
yes it is stored in CMOS
CMOS Setup
Generally, no, you cannot enter the CMOS setup after you have booted. But it depends on the exact computer and if there is a separate CMOS configuration tool. In fact, the IBM AT was like that, and it required a separate setup program that ran after the computer booted. Some of the modern computers will let you change certain CMOS settings on the fly if you install a utility their utility for doing that.