BIOS Interview Preparation Guide

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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?