BIOS Interview Questions & Answers

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FROM THE RESETING OF CMOS BATTERY FOR FEW MINUTES, THAT COULD BE FIND ON MOTHERBOARD

Software

Short for Basic Input/Output System, the BIOS (pronounced bye-oss) is a ROM chip located on all motherboards that allows you to access and set up your computer system at the most basic level. In the picture below, is an example of what a BIOS chip may look like on your computer motherboard. In this example, this is a picture of an early AMIBIOS, a type of BIOS manufactured by the AMI. Another good example of a BIOS manufacturer is Phoenix.

The BIOS and CMOS are often times thought to be the same thing, but they are not. They are two different components of a computer, but they do work together to make the computer function properly.
The CMOS setup lets you change the time and date and settings for how devices are loaded at start up, like hard drives, disc drives, and floppy drives. The CMOS setup lets you enable and disable various hardware devices, including USB ports, the onboard video card and sound card (if present), parallel and serial ports, and other devices.

1) Enter CMOS setup.
2) In CMOS setup, look for an option to reset the CMOS values to the default setting or an option to load the fail-safe defaults. With many CMOS setup screens, there will be a function key to do this. For example, the F5, F6, F9, F11, or F12 key, as shown in the picture, may be set up as a shortcut to load the default settings. Other setups may list an option that you can arrow over to using the arrow keys and pressing Enter.
3) When found and selected, you'll likely be asked if you're sure you want to load the defaults. Press Y for yes or arrow to the yes option.
Once the default values have been set, make sure to Save and Exit and not just exit.

1) Tab key is used to navigate.
2) Arrow keys are used to change values.
3) Values are automatically saved when changed, no need to save and exit like other BIOS setups.

ALFAROME
BIOSTAR
biostar
biosstar
CMOS
cmos
LKWPETER
lkwpeter
setup
SETUP
Syxz
Wodj

Press both mouse buttons repeatedly during the boot

phoenix

% p%
% p%

01322222
589589
589721
595595
598598
aLLy
aLLY
ALLY
ALFAROME
aPAf
_award
AWARD SW
AWARD PW
AWARD_SW
AWARD?SW
AWKWARD
BIOSTAR
CONCAT
Condo
d8on
djonet
HLT
J64
J256
J262
j332
j322
KDD
LKWPETER
lkwpeter
PINT
pint
SER
SKY_FOX
SYXZ
TTPTHA
ZAAADA
ZBAAACA
ZJAAADC

A.M.I.
AMI
AMI_SW
AMI?SW
BIOS
HEWLITT RAND
LKWPETER
PASSWORD
Oder

If no Windows BIOS utility is available, create a bootable CD and copy the BIOS flash utility files to the CD. Then restart your computer and boot to the CD to run the BIOS flash utility.
This option does require that your computer has a CD-Writer, blank disc, and that the CD-Writer has the capability of creating bootable CDs. Many CD-Writers have this capability, as do the CD creation software programs. The best way to find out is to either check documentation for your CD-Writer or just try creating a bootable CD and see if it works.
You also need to make sure you force a boot to the CD when your computer starts up. In most cases, there is a function key that displays a list of bootable devices your computer can use to boot. F10 and F12 are common hotkeys for displaying this bootable device list. Select the CD drive and see if the computer will boot to the CD and load the BIOS flash utility.

Check the motherboard manufacturer website to see if they have a Windows-based BIOS flash utility available for download and use. If this is available for your motherboard, this utility may be the best option to use. Typically the utility runs some of the BIOS flash process in Windows, then restart your computer and run the remainder of the flash process when the computer starts up, within DOS mode.

41. What is EFI?
42. State the differences between BIOS and EFI?
43. What is the AGP aperture size?
44. What is the role of the BIOS?
45. What are the vulnerabilities present in BIOS chip?
46. How to configure BIOS boot configurations?
47. What does the BIOS code consist of?
48. What is the role produced by Reprogrammable microcode?
49. How to invoke an interrupt?
50. What is meant by DOS hooks?

31. Mention the ways in which corrupt BIOS can be recovered?
32. What are IRQ routing errors?
33. Explain the procedure of clearing BIOS via MS-DOS.
34. What is the purpose of 18h and 19h interrupts in reference to BIOS?
35. In the BIOS GUI what does IDE channels signify?
36. What is the translation method for the IDE drive?
37. What is the SMART monitor?
38. What is the CPUID?
39. What is the ACPI suspend type?
40. What do you understand by the HPET mode?

21. What is bank interleaving?
22. What was the use of the memory hole in previous generation motherboards?
23. What does Byte Merge do?
24. What does the option Plug and Play OS signify?
25. What are legacy options in BIOS?
26. What is the CIH? Explain?
27. What is an SLIC in reference to BIOS?
28. What are reprogrammable microcodes?
29. What are the functions that user can perform with the BIOS?
30. What does the SAT/.ACHI mode signify?

11. What is non-volatile BIOS?
12. What is EEPROM in reference to BIOS?
13. What is the procedure of changing/updating the BIOS known as? Explain briefly.
14. Mention some of the settings that can be changed via the BIOS?
15. What does the power management option in the BIOS signify?
16. What is the use of the ECP in reference to BIOS?
17. How are COM ports recognized by the CPU?
18. Differentiate between the primary master and secondary slave?
19. Explain normal computer BIOS routines on being switched on.
20. What is over-clocking?

Extensions to EFI can be loaded from virtually any non-volatile storage device attached to the computer. For example, an original equipment manufacturer (OEM) can sell systems with an EFI partition on the hard drive which would add additional functions to the standard EFI firmware stored on the motherboard’s ROM.

The EFI community has created an open source shell environment. rather than booting directly into a full OS, on some implementations, the user can boot to the EFI shell. The shell is an EFI application; it can reside directly within the platform ROM, or on a device for which the drivers are in ROM.

The shell can be used to execute other EFI applications, such as setup, OS install, diagnostic or configuration utilities, and system flash updates; it can also be used to play CDs or DVDs without having to boot to a complete operating system, provided that an EFI application with the appropriate features is written. Shell commands also make it possible to copy or move files and directories between supported file systems. Drivers can be loaded and unloaded, and a complete TCP/IP stack can also be used from within the shell.

The EFI shell supports scripting through .nsh files, which are analogous to DOS batch files.

Shell command names are often inherited from the DOS command line interpreter COMMAND.COM or the Unix shell. The shell can be viewed as a functional replacement for the DOS command line interface and the BIOS text user interface.

An EFI boot manager is also used to select and load the operating system, removing the need for a dedicated boot loader mechanism (the OS boot loader is an EFI application).

The Extensible Firmware Interface (EFI) is a specification that defines a software interface between an operating system and platform firmware. EFI is intended as a significantly improved replacement of the old legacy BIOS firmware interface historically used by all IBM PC compatible personal computers. The EFI specification was originally developed by Intel, and is now managed by the Unified EFI Forum and is officially known as Unified EFI (UEFI).

1. Define the purpose of BIOS in a system?
2. What are the different types of BIOS?
3. What is POST in terms of BIOS?
4. Why are POST cards used?
5. Define CMOS in reference to BIOS?
6. How does a bootstrap loader work?
7. How can the BIOS accessed?
8. What are BIOS routines?
9. What is a BIOS interrupt call?
10. How is an interrupt invoked?

CIH, also known as Chernobyl or Spacefiller, is a Microsoft Windows computer virus which first emerged in 1998. It is one of the most damaging viruses, overwriting critical information on infected system drives, and more importantly, in some cases corrupting the system BIOS. The virus was created by Chen Ing-hau who was a student at Tatung University in Taiwan. 60 million computers were believed to be infected by the virus internationally, resulting in an estimated $1 billion US dollars in commercial damages.

Interleaved memory is a technique for compensating the relatively slow speed of DRAM. The CPU can access alternative sections immediately without waiting for memory to be cached. Multiple memory banks take turns supplying data. An interleaved memory with "n" banks is said to be n-way interleaved. If there are "n" banks, memory location "i" would reside in bank number