My new desktop did not come with any BIOS. When I boot it, the screen stays black for about a minute and suddenly shows the OS. Are there any free BIOS programs out there, and how does installing them work? I'm sure the process isn't like installing a typical program.
Your computer definitely did come with a BIOS. It's impossible for a computer to boot up without one. Most likely your BIOS just doesn't have a splash screen, or has it turned off. What is the brand of your computer? You can probably find information with a quick google search on what the BIOS configuration key is for your computer; pressing that on start-up will open the BIOS options for you, where there may be an option to turn on the splash screen.
A BIOS is specific to the motherboard. You can get BIOS updates from the motherboard manufacturer. It is very unlikely that your computer did not come with a BIOS unless it is a Mac; Intel-based Macs use EFI, and PowerPC-based Macs used Open Firmware. It is more likely that the BIOS is simply set to hide all BIOS messages during boot time. You can try to google your motherboard model number to see if you can get a manual for it. It should have the keyboard shortcut listed to get into the BIOS.
The keyboard shortcut is usually the delete key, the escape key, or one of the F-keys on the top of the keyboard like F1 or F10. You would have to press the key while the computer is starting up before it gets to the operating system.
Uuh, I'd advice you to return it to them.
Although you can flash BIOS, you still need a BIOS (Basic Input Output System) to execute any such actions. Or a kind of an EPROM ...
But, in any case, it is not an operation which you'll want to do (or probably know how) without knowing the delicate intrinsics ... trust me on this one.
I'd just return it, and explain the problem (but I'm pretty sure it did come with a BIOS and the problem is somewhere else).
Additional edit: Just re-read the question once again. "suddenly shows OS" - you have a BIOS therefore. So, what you're interested in is "flashing" if your motherboard supports it, but the question remains, why would you want to risk bricking your computer, if it seems to be working.
Btw, why do you want to flash it, in the first place?
In some BIOS-es you can set the option to skip some parts of the booting process (skip showing them at least) - so you might want to go through it and see if that's what's interesting you.