BIOS is built-in software that runs by the computer when it powering on. BIOS was invented by Gary Kildall and first appeared in the CP/M operating system in 1975.
This program is usually stored in motherboard ROM and it stores information about the computer hardware. In the
computer starting time the BIOS loads configuration data into the main memory and
performs a routine hardware diagnostic test, this test is called POST (Power on
Self-Test). POST will produce beep sound when it found any error or malfunctions.
POST Beep Codes - CompTIA A+
|
|
Beep Code
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Error Type
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Steady, Short Beeps
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Power Supply may be bad
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Long continuous beep tone
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Memory failure
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Steady, long beeps
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Power Supply may be bad
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No beep
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Power supply bad, the system not
plugged in, or power not turned on
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No beep
|
Some issue with the 'beeper'
itself.
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One long, two short beeps
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Video card failure
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The main function of the BIOS is to initialize and test all hardware components attach to the computer and load the part of the operating system. BIOS also provides a medium that facilitates the application programs and operating system to interact with the keyboard, display and other I/O devices.
The following are the list of activities performed by BIOS:
BIOS handles the power management and initialize registers.
It checks and loads the device drivers and interrupts
handlers to the RAM.
It is used to display system settings.
BIOS specifies the devices that are Bootable.
BIOS initializes the Bootstrap sequence.
CPU - Central Processing
Unit
CPU Ratio
This option is used to overclock the CPU. It allows changing
the frequency multiplier of the processor.
CPU Voltage
Processor over
clocking requires higher voltage this will help to little adjustment.
Host Clock / PCIe Clock
This is used for adjusting the processor's onboard PCI Express controller frequency. It
will help to improve some graphics performance.
C#State
Options
These are processor power levels. It is useful to turn off when attempting
extreme overclock to keep the processor
from switching power states.
x86 Virtualization
This option will help to enable Virtualization Technology
in the computer. We need to understand BIOS instruction to configuring this option
correctly because this option may change as per the vendor. (In Intel- VT-x, AMD
- AMD-V).
Chipset
Graphics: These options are normally for
switching the graphics adapter from primary to secondary and also can change the memory of the adapter.
Onboard Peripherals: This option is used to configure the onboard peripheral features.
E.g. enable front panel
audio
Memory – Internal and
External
Memory Frequency
This option will help to change the operating
frequency of the memory. Better to use the same frequency RAM.
Storage
IDE: This is a backward-compatibility
feature. Use the IDE option when the OS doesn't support SATA. E.g. Option IDE -
Install Windows 98 on a SATA HDD.
AHCI: This option is used to enable SATA's
features.
RAID: This option will help to configure
RAID using SATA ports. Otherwise, it acts like AHCI.
S.M.A.R.T: Self-Monitoring, Analysis and
Reporting Technology detects and reports
on various indicators of drive reliability, with the intent of enabling the anticipation of hardware failures.
Legacy USB Support: This option only provides support of
the USB ports during boot up and for other activities when the OS isn't fully
loaded.
System Power Configuration
Power Option
S-State configuration: These are the power level of the
computer systems.
S1: Power on suspending- CPU stops executing instructions, but
both it and RAM remain on.
S3: Standby/Sleep/Suspend
to RAM- The contents of RAM are
kept and remains powered. S4:
Hibernate- The contents of RAM are stored in the HDD/SSD, then the
system powers off completely.
ERP S5: Shutdown the system completely.
Wake on LAN: Turning on the system using the Wake
on LAN protocol through a network.
State after Power Loss: If the computer has a loss of power,
the computer can do the following once power is restored
Last state: If the computer was off, the computer
will remain off. If it was on, it'll power back on.
Always on: The computer will always power on
after power loss.
Always off (default): The computer will remain powered off.
Boot Devices and Security
Boot and Security
Fast/Ultra-Fast Booting: This will minimize POST times.
Num Lock on Boot: Num lock should be on or off on boot.
Boot/POST beep: Produce beep alert the computer
doesn't boot up.
Boot Order: This configures which storage devices
to boot from in order.
Setup Password: Set up a password that must be entered for booting and configure BIOS.
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