BIOS

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BIOS CMOS
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We have covered the following subjects

• BIOS ROM
• CMOS CMOS Battery
• Configuring the BIOS
• Configuring the BIOS. Cont
• Configurable Devices
• Un configurable Devices
• Option ROM
• Device Drivers, Accessing CMOS Setup, Editing The
  BIOS Parameters, Navigating, Saving and Exiting
• Summary

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BIOS

• The BIOS program controls the start-up process
  and loads the operating system into memory.
• The BIOS is an example of firmware.
• Most BIOS chips are 64k in size, though there is
  384k address space available for the BIOS to use.
• SCSI devices include a BIOS chip on a device
  itself. These devices have their own ROM chip
  called an option ROM.

What is the BIOS? BIOS stands for, Basic
input output system. The BIOS is a program stored
in a read-only memory (ROM) chip that the CPU
automatically loads and executes when it receives
power.
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CMOS

• The CMOS battery can be a low-voltage dry cell,
  lithium mounted on the motherboard, or even AA
  batteries in a housing clipped on a wall inside
  of the case. The electric current is about 1
  millionth of an amp and can provide effective
  power for years.
• If the voltage of the battery drops
  significantly, you may lose your CMOS settings
  every time you power-off or power-on your
  computer. If a CMOS battery fails, replace it and
  afterwards re-enter the CMOS information.

What is CMOS? CMOS stands for Complementary
Metal-Oxide Semiconductor (CMOS). CMOS memory is
a special RAM chip powered and maintained by a
small battery that holds basic configuration data
your computer needs in order to start.
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Configuring BIOS

• System Time/Date - Set the system time and date
• Boot Sequence - The order that BIOS will try to
  load the operating system
• Plug and Play - A standard for auto-detecting
  connected devices should be set to "Yes" if your
  computer and operating system both support it
• Mouse/Keyboard - "Enable Num Lock," "Enable the
  Keyboard," "Auto-Detect Mouse"...
• Drive Configuration - Configure hard drives,
  CD-ROM and floppy drives
• Memory - Direct the BIOS to shadow to a specific
  memory address
• Security - Set a password for accessing the
  computer
• Power Management - Select whether to use power
  management, as well as set the amount of time for
  standby and suspend
• Exit - Save your changes, discard your changes or
  restore default settings

To enter the CMOS Setup, you must press a certain
key or combination of keys during the initial
startup sequence. Most systems use "Esc," "Del,"
"F1," "F2," "Ctrl-Esc" or "Ctrl-Alt-Esc" to enter
setup. There is usually a line of text at the
bottom of the display that tells you "Press ___
to Enter Setup." Once you have entered setup,
you will see a set of text screens with a number
of options. Some of these are standard, while
others vary according to the BIOS manufacturer.
Common options include
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Configuring BIOS. Cont

• Be very careful when making changes to setup.
  Incorrect settings may keep your computer from
  booting.
• When you are finished with your changes, you
  should choose "Save Changes" and exit. The BIOS
  will then restart your computer so that the new
  settings take effect.
• The BIOS uses CMOS technology to save any changes
  made to the computer's settings.
• With this technology, a small lithium or Ni-Cad
  battery can supply enough power to keep the data
  for years. In fact, some of the newer chips have
  a 10-year, tiny lithium battery built right into
  the CMOS chip!

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Configurable Devices
The main bootable devices in the BIOS are

• Hard Disk Drives
• Floppy Drives
• CDROM Drives

Then you have the Boot device priority
1st Boot Device Floppy drive 2NDBoot
Device CDROM 3rdBoot Device Hard
Drive 4thBoot Device

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Un-configurable Devices

• A computer system can contain several BIOS
  firmware chips.
• The motherboard BIOS typically contains code to
  access fundamental hardware components such as
  the keyboard, floppy drives, ATA (IDE) hard disk
  controllers, USB human interface devices, and
  storage devices.
• In addition, plug-in adapter cards such as SCSI,
  RAID, Network interface cards, and video boards
  often include their own BIOS, complementing or
  replacing the system BIOS code for the given
  component.

Plug and play and hot swappable devices are not
configurable in the BIOS because the Plug and
play and hot swappable devices also have BIOS.
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Option ROM
An Option ROM typically consists of firmware that
is called by the system BIOS. For example, an
adapter card that controls a boot device might
contain firmware that is used to connect the
device to the system once the Option ROM is
loaded.
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In this short video, which can be paused and
rewound, you can see how to

• Access CMOS Setup
• Navigate around CMOS
• Edit the BIOS Parameters
• Find Device Drivers
• Save and Exit

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Summary
So what have we talked about? We have talked
about the CMOS BIOS. We hope that this
presentation has helped you to understand the
BIOS CMOS better.
Any Questions?