BIOS Interview Questions And Answers

BIOS or Basic Input/Output System is the first program accessed by the processor during start up to ensure that all the other basic programs, hard drives, ports, peripherals and the central processing unit are in good working condition. BIOS is different from the computer's operating system. The operating system resides in the hard drive and provides the user interface that can be seen on the screen after start up. The BIOS program, on the other hand, can be found right in a flash memory chip or ROM located in the motherboard. It is the basic requirement for booting a computer.
BIOS Functions
BIOS has several functions in a computer but its most important task is to load the operating system. BIOS provides the microprocessor its first instructions upon activating the computer. The instructions of the BIOS to the microprocessor during start up are the following: power on self test which tests the operating status of all the hardware in the computer, activation of other BIOS chips in some other computer components like SCSI and graphics cards, checking and management of computer peripherals through low level routines during the start-up process, and management of clock, hard drive and other settings.

in pc's the most common are the AWARD,AMI, AND phoenix

For the person who still has no idea about the BIOS on your PC, notice when you first turn on your PC or laptop a few screens pop up. It might be a logo such as DELL or HP or ASUS, Tyan , AMI BIOS, AWARD BIOS etc. You might also see a memory count . This is all part of the POST (Power On Self Test). POST is a test the BIOS runs before it hands over control to the OS (Operating System). You can see more of the post if you disable the logo option in your BIOS. Otherwise just know that if you see a logo the POST is running.

There are two methods to update yiour BIOS chip:

1. Flash it (software method)

2. Program it with an EEPROM programmer. This is a hardware method . This is how we at BIOSMAN program sall our BIOS chips.

Complementary metal oxide semiconductor (CMOS) refers to a chip inside your computer that saves your BIOS settings. As a result, the terms CMOS and BIOS are sometimes used interchangeably.

Advanced Configuration and Power Interface (ACPI) is an industry standard that defines power management features and other configuration information for computers. Some previous versions of BIOS do not support ACPI, and so the computer may not successfully enter advanced power modes such as sleep or hibernate. For more information, check the information that came with your computer or go to the computer manufacturer's website.

Nonvolatile BIOS memory refers to a small memory on PC motherboards that is used to store BIOS settings. It was traditionally called CMOS RAM because it used a volatile, low-power complementary metal-oxide-semiconductor (CMOS) SRAM powered by a small battery when system power was off.

Overclocking is the process of making a computer or component operate faster than the clock frequency specified by the manufacturer by modifying system parameters. One of the most important techniques is running at a higher clock rate (more clock cycles per second; hence the name "overclocking"), but other parameters, such as CPU multiplier and memory timings, can also be changed and would be considered to be overclocking. Operating voltages may also be changed (increased), which can increase the speed at which operation remains stable. Most overclocking techniques increase power consumption, generating more heat, which must be dispersed if the chip is to remain operational.

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

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.

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?

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).

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 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.

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.

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?

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?

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?

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?

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.

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.

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

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

% p%
% p%

phoenix

Press both mouse buttons repeatedly during the boot