eli5: Why is it bad to unplug a computer when it’s updating it’s BIOS?



eli5: Why is it bad to unplug a computer when it’s updating it’s BIOS?

In: Technology

The BIOS is the first thing the motherboard accesses in order to start up and eventually access some storage device to load the operating system from.

When overwriting this firmware, if something happened that leaves the firmware in an unusable state, such as a power loss while the firmware is still being overwritten, it’s possible to end up with a firmware that is incapable of functioning

This will lead to a useless motherboard, except in some cases where the chip holding the firmware can be replaced physically.

Imagine the code like a bunch of tetris pieces filling up a square leaving no empty spaces.

Because there are no spaces, to update pieces, you’d have to pull the old ones out, rearrange them, and put them back so there are no empty spaces again

During this process you have to keep those tiles outside of the box. The area outside of the box, however, only exist while the computer has power.

Unplugging the computer deletes blocks that are essential and necessary, but were just out while they found a new place to fit in

BIOS stand for Basic Input/output system. It’s essentially the software that allows your computer to power on, and load your operating system (knowing where to look/which drive, how much memory is installed, and so forth). It has to be working in order for the computer to work.

Updating a BIOS is a little bit risky. Sure the BIOS is running while the computer is on, but if the power blips, and the update software isn’t done copying the new BIOS into the controller, then there won’t be a BIOS on the controller to load from the next time the power comes on. In the olden days, if you screwed up updating your bios, you were left with a very expensive brick, as there wasn’t anything that you could really do. Nowadays, they’ve built all sorts of protection into the BIOS that will minimize the risk of making the controller unusable.

The BIOS firmware is the first thing used to get your computer running. If you unplug the power during the update process the Firmware will likely get corrupted and become unusuable.

Your computer won’t be able to power on, and there’s no easy way to fix it.

The technical term for this is ‘bricking’ ie your computer is now as worthless as a brick.

Think of it like a rollercoaster with a chain lift hill to start. The BIOS is the chain lift. If you damage that part, the rest of the ride isn’t going to happen, whether or not it’s all there and otherwise functioning perfectly.

The BIOS is the software necessary to get the rest of the process going to get the computer to start up. If you switch off while that’s updating, it can render it useless, meaning the rest of the process can’t occur, and you’re left with a totally dead computer.

BIOS is the first piece of software a computer runs when it powers up. When you power up a computer, the BIOS is loaded into the CPU. Then the BIOS finds and runs the OS, and the OS manages your user programs (e.g. your web browser)

If you unplug your computer while updating your web browser, it may leave the web browser in an un-usable state. These days, many updater software are coded in a way that can recover from that, but even in worse case, you can simply use your OS to uninstall the malfunctioning browser and reinstall a good version. You may lose some data but at least you end up with a working browser.

If you unplug your computer while updating your OS and the OS ends up in an un-usable state, you can use the BIOS to remove the OS and reinstall a good version. You may lose a lot of data but at least you end up with a working OS.

But the BIOS is the end of the line. If you unplug your computer while updating your BIOS and the BIOS ends up in an un-usable state, there is no software you can use to recover from it.

BIOS (loaded into the RAM) is doing the BIOS update. It wipes the little flash memory chip that stores it and starts rewriting it with the new. If the computer is shut off, the RAM is emptied and the old BIOS is lost, leaving only the nonfunctional half-written one on the flash chip.

Because then you end up with half the old BIOS and half the new BIOS, and if you aren’t lucky, the two pieces won’t fit together properly and your computer won’t boot.

Some motherboards have a second copy of the BIOS as a backup, which they’ll use if this happens.

The uefi/bios is like the engine in a car. While it’s updating, it’s putting a new “engine” in the computer. If you interrupt the process, bam. You have an expensive brick now.