understanding the BIOS

BIOS means Basic Input Output System. It is the first thing that operates when the computer is turned on, and is separate from the OS, though it interacts with the OS. The term BIOS is generally used interchangeably with the terms CMOS and Setup, though the three terms mean three generally distinct things. This training discusses the basics of the BIOS, BIOS settings you should be concerned with, and how to update a BIOS.

1. The System BIOS

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Basic functions

The BIOS performs the following boot functions in a typical computer system:

- Takes inventory of all hardware in the system and checks to ensure each components' basic operability.
- Recognizes and configures new hardware such as hard drives and floppy drives.
- Locates a valid OS and transfers the control of the system to that OS after boot functions have completed.

The BIOS also performs the following tasks during the normal operation of the system:

- Interacts with the OS to configure hardware behavior.
- Enables and disables integrated devices.
- Interacts with the 'hardware abstraction' layer to ensure compatibility between newer hardware and older applications.
- Affects system power properties.
- Provides a level of system security.

Post (Power On Self Test)

- When the computer first turns on, a POST is performed to ensure that all critical devices are operating.
- Devices checked include memory, drives, cpu, system timer, chipset, all peripheral cards, and memory.
- When all devices are deemed operable, the BIOS passes system control over to the OS.
- If a device is malfunctioning, and error code is generated in the form of beep codes and/or text.
- During POST, the system BIOS reads peripheral BIOS routines and runs them (see below).

The Peripheral BIOS

- Each installed device has its own 'BIOS'. This 'peripheral BIOS' interacts with the system BIOS.
- It is the peripheral BIOS which identifies the device to the system BIOS and the OS.
- This is how the OS determines if it has a driver for the device when the device is first installed.

Example: When the computer is turned on, the system BIOS looks first to the video BIOS. The video BIOS identifies itself and initiates the video capabilities. This is why you often see the identifying video adapter information before you see system information on power-up.

CMOS

- Complimentary Metal Oxide Semiconductor
- The physical semiconductor used to carry the subroutines that run the BIOS

Setup

- The actual parameters and system settings that can be configured.
- Accessed on startup. Method of access depends on vendor.

Examples: Dell: press the f2 or 'delete' key ; Compaq: press f10

The Battery

The BIOS is powered by a battery that retains the data when the system is off.
Modern BIOS batteries are standard NiCad batteries

2. Important BIOS Settings

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Note: This does not hold for proprietary BIOS setups that you may encounter in some older Compaq systems. In addition, not all BIOSes have all of these features.

Standard settings | Advanced features | Advanced chipset features | PCI/PnP Configuration | Power Management | Integrated peripherals | IDE device setup/autoconfiguration | Security/password | Hardware device settings | Autoconfiguration and Defaults

Standard Settings

These are basic settings that involve system time/date, and the detection of system drives. In addition, it configures system behaviors during certain errors. See PCguide details of standard/drive settings.

Advanced Features

Advanced drive settings and performance tweaks. Some of these settings can be disabled in the event of system failures. Frequently includes boot order settings. See PCguide details of advanced feature settings.

Advanced Chipset Features

Tweaks which will affect critical system performance involving memory, system timer, cache, etc. You will not affect these settings under any circumstances. See PCguide details of advanced chipset feature settings.

PCI/PNP Configuration

Tweaks which will affect the PCI bus (over which PCI devices run) and PnP (Plug and Play) behavior. You will not affect these settings under any circumstances. See PCguide details of PCI/PnP configuration settings.

Power Management

Affects the power down/power up of different components in the system. Includes things like 'wake up on lan'. Can affect app functions that rely on constant component uptime. See PCguide details of power management settings.

Integrated Peripherals

Enables or disables peripherals integrated into the motherboard. Choices usually include network cadapter, video adapter and audio adapter ( if they are integrated). This will be very important for you if you need to replace an integrated peripheral's function with a non-integrated card. See PCguide details of integrated peripherals settings.

IDE Device Setup/Autodetection

Drives are generally autodetected in the 'standard settings' part of the BIOS. This section allows advanced and detailed configuration of each drive. See PCguide details of hardware device settings.

Security/Password Settings

Sets passwords for system access. Note: All BIOS passwords can be circumvented by removing the BIOS battery and then re-inserting it, or setting the BIOS jumper to defaults. See PCguide details of security/password settings.

Hardware Device Settings

All new computers feature 'jumperless' configurations. You can set CPU speed, multipliers, and other parameters through the BIOS. This is where you set such parameters. See PCguide details of hardware device settings.

Autoconfiguration and Defaults

Sets all BIOS settings to the 'out of the box' configurations. Warning: setting the BIOS to defaults can cause some devices and apps to malfunction. Never set the BIOS to defaults unless explicitly instructed to. See PCguide details of hardware device settings.

3. Identifying and Flashing the BIOS

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Flashing the BIOS: replacing the software subroutines in the current BIOS with an updated image that holds new instructions. Usually used to fix system bugs not having to do with the OS, or to expand system capabilities. DO NOT FALSH THE BIOS UNLESS EXPLICITLY INSTRUCED TO DO SO.

Identify the BIOS - Download the Unicore BIOS Wizard

Identifying the BIOS can be easy or very difficult. This training includes a utility called 'Unicore BIOS wizard' that will identify any BIOS.It is small enough (450k) to load onto a floppy, take to any computer, and run it. Download it here.

Flash BIOS Procedures

- If the BIOS belongs to a major vendor system, simply find the BIOS on that vendor's download site.
- If the BIOS belongs to a mom n' pop system, and you can identify the motherboard, you can get the update from that motherboard's site.
- If the BIOS belongs to a mom n' pop system, and you cannot identify the motherboard, you would do well to use Unicore.

BIOS flash procedures vary from vendor to vendor. Generally, the process involves:

- Downloading the 'image' that will replace the current BIOS.
- Extracting the image to a floppy disk.
- Booting the system with that floppy. The update is usually automatic, or provides instructions.

Note: Some vendors, like ASUS motherboards, require you to download an update program, AND a separate image to the same floppy.

Vendor Resources

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