to enter the BIOS during boot up hold down one of the following keys:
Hold down the [Del] key
Hold down the [F1] key
Hold down the [F10] key
To enter the BIOS from a DOS prompt...( ...NOT from inside windows)
[Alt][Ctrl][Esc]
[Alt][Ctrl][Enter]
[Cntrl][Alt][A]
[Cntrl][Alt]
Some manufacturers have their own way for entering BIOS as shown below...
Acer - Ctrl+Alt+Esc
Compaq - F10
Compaq Presario - Press [Alt] [Ctrl [Esc] at boot when you see the "Compaq" log in big letters
Dell - F1 or Del.
Gateway 2000 - F1
Hewlett Packard - F1
IBM
Older Models - In order to get into the configuration of the IBM setup screen (CMOS) screen you need to hold down both mouse buttons during boot-up.
Aptiva - Press F1
Leading Edge
Fortiva 5000 - [Ctrl] [Alt] [A] or [Cntrl] [Alt]
NEC - F2
Packard Bell - F1 or F2
Sharp Laptop 9020 - F2
Sony - F3, then F2, or F1
Tandon computers - Hold down the [Esc] key after turning on power
Toshiba Laptops - Toshiba Utility