What is computer? I consider computer is a machine that quickly and automatically runs algorithm. The computer of Chinese text is 電 (electrical) 腦 (brain). Our brains are computers but not quick and correct. For example, I am an BIOS engineer. How do I proof it? I have blurred BIOS algorithm in my mind but it cannot be correctly run in my brain. I can tell you the algorithm but not the whole. I need to write BIOS program and run it in a machine to make sure that I know something in BIOS.
The machine, my brain, is not smart. I admire mathematicians who can present their theories in boards with very long formulas without computers. For me, a computer is necessary to help me thinking. I need burn BIOS in PC and see the process so that I can learn more.
But I don't want to use my PC to update BIOS. That has risk than using my brain. The idea is to use PC to emulate PC. I use a PC emulator to run a simple BIOS without breaking my PC at home. That is why I use Bochs, a PC emulator.