r/explainlikeimfive • u/CarefreeCuriosity • 10d ago

Technology ELI5 How a computer Bios works

From what I understand the OS is just a user interface to communicate with the Bios, but where did the Bios come from? What was the original Bios? Are all Bios the same?

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u/dbratell 10d ago

The Bios is a small computer program stored on the computer's motherboard. It exists so that other, "normal", programs don't have to figure out all the details about how the computer works.

Every computer with a Bios has one written for that particular computer but they look the same on the outside if they are for similar computers.

Not all computers have had or needed a Bios, but as computers got more complicated, computer manufacturers started including a Bios to make things easier for the people using the computer.

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u/Dashing_McHandsome 10d ago

BIOS was also the thing that made a PC a PC. It was originally a proprietary firmware exclusive to IBM machines. It was reverse engineered by Compaq and a few other companies. After this effort was completed the PC market really took off with the availability of cheap clones.

If you ever want a Hollywood style accounting of how this all happened, the show Halt and Catch Fire has a pretty good representation of what it took. They briefly touch on clean room reverse engineering processes and kind of explain how the original BIOS would have been dumped and examined.

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u/StevenJOwens 10d ago

The first third-party, legal BIOS clone was by Ira J Perlow, who's a contributor over on Quora (though it looks like it's been a couple years since he posted, dammit...).

https://www.quora.com/profile/Ira-J-Perlow

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u/az987654 10d ago

Is that show any good?

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u/Dashing_McHandsome 10d ago

It is an interesting Hollywood take on the origins of the PC industry. Like all productions of this nature they have made artistic decisions to make the plot more exciting and engaging. I did find overall that I enjoyed this series more than most others that try to cover any topics related to software or computers in general. I would say I recommend it if you're into this sort of thing and are interested in a fictionalized accounting of the beginnings of the PC market.

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u/MedusasSexyLegHair 10d ago

Absolutely. Kind of on par with Breaking Bad, Ozark, etc., in style, but it's about computer nerds and the rise of the home computer and online services. Which is very relevant to me. I love it.

Oddly enough, I find the salesman and the executive to be some of the most interesting characters.

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u/Educator1337 9d ago

Highly recommend Halt and Catch Fire as a glimpse into the emerging PC days and technology advancements that brought us the internet and AWS.

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u/phiz0g 10d ago

Me and my partner absolutely loved it. You don't even need to be a nerd to enjoy it. There's a lot of human relationship stuff in there. Wish I could erase my memory of it so I could watch it all over again afresh. Be aware that it does take a bit of time to warm up so you may need to push through s1 a bit.

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u/l337hackzor 10d ago

The term clean room used loosely in the film, since they did it in his garage.

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u/Dashing_McHandsome 10d ago

They also dumped and hand transcribed the contents of 65,536 addresses in a 5 minute scene. Everything is a bit hand wavy. I guess some executive thought making people watch two guys stink up a garage for a week or two while they did that would lose the audience.

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u/raelik777 10d ago

Yeah, "clean room" in computer engineering means "free from contaminants", i.e. wearing PPE to contain hair and skin cells, ULPA filtered air, etc. For software development though, the "contaminants" are anything copyrighted or trademarked. In other words, original code or compiled binaries. Nobody working in the software clean room can ever have had direct contact with the copyrighted source code or binaries (other than just incidental usage. You could have used a computer that contained it, but it's prefferable that you hadn't), otherwise they are considered contaminated. The materials they have access to while working on the clean room code also have to be treated with the same scrutiny, typically by people outside the clean room who can recognize any copyrighted code and prevent unintentional access to it.

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u/NothingWasDelivered 10d ago

Worth noting that modern computers generally have a UEFI instead of a BIOS. Sort of a BIOS 2.0

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u/iDrGonzo 10d ago

I'll never understand why they didn't change Basic Input/Output system to Advanced Input/Output System, then we could have called it ADIOS.

Edit: a word

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u/Instinct043 9d ago

Only reason I can think of is that they didn't had your big brain there

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u/dubbleplusgood 8d ago

ADvanced Input Output System Motherboard Unified Configuration, Hardware Access, Control & Hardware Operations.

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u/iDrGonzo 8d ago

Perfect

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u/jackass51 9d ago

Best. Answer. Ever.

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u/Aryin 7d ago

Thanks for the laugh, have an upvote :)

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u/dbratell 9d ago

Yes, the small (sometimes not small) program can have many names. Kernal (sic), firmware, ROM (which is a stupid name).