1. If I am new, how long it takes to write BIOS for embedded PC?

Depends what you mean writing from scratch could take years. Compiling LinuxBIOS on supported motherboards could take a few hours.

2. What knowledge is need to write BISO?

Electronic knowledge the ability to read and understand chip datasheets

3. Suppose i purchase BIOS from AMI, Award or Phoenix, do i customize BIOS according to my Board.

Look at LinuxBIOS website

4. What tools are needed to write BIOS?

Linux, In circuit debuggers, and complete datasheets of your hardware.

5. From where do i get complete understating of BIOS?

LinuxBIOS web site. Learning to program microcontrollers first.

6.I have ARM7 LPC Board. Can I write Sample BIOS for this Board?

Dam rights you can

7. What is difference between BIOS and Boot Loader?

BIOS handles all your Inputs and Outputs. All the chips on your motherboard down to the circuit level. A bootloader just copies your os to memory.

Tyler Pohl