What is BIOS ?
-BIOS is the software located in the system ROM Chip of the motherboard. The BIOS is used to control the system boot process and device settings. Also BIOS initializes the operating system boot process.
(BIOS) Basic Input Output System
(software) (CMOS) Complementary Metal Oxide Setup
(Battery)
SYSTEM BOOT PROCESS:Stage 1 – CPU wakes/power on
When we press the power button electric charge is sent into the CPU and it switches on. Then the CPU starts the BIOS.
Stage2- Post Process ( Power on self test)-Then the BIOS runs the post process
-Post will scan for all devices connected to the system and will check power supply and device status.
-If all devices are working properly then the next stage will be loaded. If there are any errors then POST error codes will be given.
POST ERROR CODES
-Error codes can be of 2 types; Beep codes or Numeric/Text codes.
Beep Codes:
1. A single happy sounding beep means that all devices are functioning properly.
2. A long repeating beep means problem with system RAM. Check RAM and RAM slots.
3. One long and 3 short beeps means problem with display. (Graphic card)
4. A rhythmic beep means thermal heating. (CPU overheat)
Numeric/Text Codes:100 series error (100-199) -Motherboard
200 series error (200-299) -RAM
300 series error (300-399) - Keyboard
400 series error (400-499) - B/W video
500 series error (500-599) -Color Video
600 series error (600-699) -Floppy drive
1700 series error (1700-1799) -Hard Drive
Stage 3- Operating System loading
-If the POST was successful then the BIOS will located the System Boot device.
-Then the Boot process is handed over to the operating system. Then OS Boot Process is started.
IMPORTANT BIOS Settings1. Date and Time
-The system date and time is controlled and stored in the BIOS.
-if the time is changed in BIOS it is auto changed in windows and vice versa.
-if the time is running slow or always shown incorrectly it means that the CMOS is low in power, needs to be replaced.
2. Drive Configuration-After connecting hard drives, CD/DVD and floppy drives they need to be initialized in BOIS in order to function.
-Now a day’s all BIOS have auto detect function for drives.-If we want we can also disable drives from BIOS.
3. Boot Device Priority/ Boot Sequence.
-Boot sequence is the order in which the computer searches for a boot device.
-The Boot device is the device in which our operating system is stored.
-The Default Boot Sequence is :1st Boot Device: Floppy
2nd Boot Device: Hard Drive
3rd Boot Device: CD/DVD
-For new installation, we use CD/DVD device as the 1st boot device.
4. Supervisor and user password
Supervisor Password: if we set this then every time we try to open BIOS we will need to enter the password or else BIOS will not open.
User Password: If we set this, then every time we switch ON the computer will need to enter this password or else the computer will not boot.
These passwords are used to prevent unauthorized access to the computer or BIOS.
5. Port Configuration-Through BIOS we can enable/disable all ports such as serial, parallel and USB.
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We can also change speed for USB ports to Hi Speed (480 Mbps) or Full Speed (12 Mbps)
6. CPU Configuration-Also some BIOS will display the CPU specification and temperature details.
7. Load BIOS Defaults.
-This can be used to reset the BIOS to the default factory setting.
8. Load optimum setting
-This will auto set all settings for us.
9. Save and Exit (F10)10. Exit Without Saving (Esc)Entering BIOS-During startup we need to press the associated key on the keyboard.
-this key differs according to the type of motherboard.
-It can be any of the following;
Del, F1, F2, F9, F12
We can also use the BIOS Jumpers located on the mother board to remove password.
