Normally when you start up your computer, it will automatically start by reading the computer’s internal hard drive. However, if you want the computer to boot up from a DVD or USB, you’ll need to change your computer’s boot order to list these first.
What is a Boot Sequence
During the boot process, the computer checks itself to be sure all is well, loads some minimal operational software and loads the operating system.
Each time a computer boots up, it goes through an initial series of processes, or sequence of events, which is aptly named a "boot sequence." During the boot sequence, the computer checks itself to be sure all is well, activates the necessary hardware components and loads the appropriate operational software then loads the operating system so that a user can interact with the machine.
Alternatively called boot options or boot order, the boot sequence defines which devices a computer should check for the operating system's boot files and startup. It also specifies the order in which the computer’s devices are checked.
The sequence of events in the boot sequence is as follows:
- Accessing BIOS/ROM: The boot sequence begins by accessing the computer's BIOS on Windows PCs or the system ROM on a Macintosh. The BIOS and ROM contain basic instructions that tell the computer how to boot up.
- Computer CPU received startup information: These instructions from the BIOS/ROM are then passed to the computer's CPU.
- Computer memory received information: The CPU then begins loading information into the system RAM.
- Loading the operating system: Once a valid boot disk or startup disk is found, the computer begins loading the operating system into the system memory.
- The computer is ready for use: After the operating system finishes loading, the computer is ready to be used.
The period of the boot sequence can take anywhere from a few seconds to several minutes, depending on the computer's configuration. Note that if the system is booting from a CD or DVD, the boot time may be significantly longer than if the computer is booted from a hard drive.
In addition, if your computer was turned off unexpectedly, the boot time might increase since the system may perform some additional checks to make sure everything is OK.
What should my boot sequence be?
You can set your boot sequence to how you want the computer to boot. For instance, if you never plan on booting from a disc drive or a removable device, the hard drive should be the first boot device.
Note that, if you're trying to fix a computer or reinstall its operating system, you may need to change the boot sequence. The most traditional first boot selections for these tasks are an optical disc drive or a removable drive (thumb drive).
You can change the boot order’s list and re-order it in the computer's BIOS, as shown below.
Steps on How to Change System Boot Order
You can change the boot order from your computer’s BIOS setup utility. To find out how just follow the steps below:
Note: this can vary between different PCs, so the below steps are only for general guidance. If you’re unsure, please check with your manufacturer first.
Step 1: Enter your Computer's BIOS set up utility
- To enter BIOS, you often need to press a key (or sometimes a combination of keys) on your keyboard just as your computer is starting up.
- If you’re not sure which key this is, restart your computer and watch out for the information on the screen at the very beginning of the start-up process. Somewhere here, it will often say something like Press XXX to enter setup.
- Make sure you press the setup key quickly before your computer starts loading from its internal drive, otherwise restart your computer and try again.
Note: If you can’t find the information about the key you need to press, Lifewire has produced a handy guide listing the most common keys used for different types of computers and motherboards, which can try taking a look at.
Step 2: Navigate to the boot order menu in BIOS
- Once you enter your computer’s BIOS setup utility, look for an option to change the boot order.
- All BIOS utilities are slightly different, but it might be under a menu option called Boot, Boot Options, Boot Sequence, or even under an Advanced Options tab
Note: You also might not be able to click with your mouse in a BIOS utility, so use the instructions on the screen for how to navigate between the menu items
Step 3: Change the Boot Order
- Once you’ve located the page for boot order options in BIOS, you’ll see a list of options that your computer can load up from.
- Again, these options will vary slightly between computers but will typically include: Hard Drive, Optical (CD or DVD) Drive, Removable Devices (e.g. USB or Floppy), and Network.
- Change the list order so that USB Device or Removable Devices is listed first.
Step 4: Save your Changes
- Make sure you save your changes before exiting BIOS for the changes to take effect
- Navigate to the Save and Exit or Exit menu and choose an option that says, “Save Changes” or “Exit with Changes Saved” (or something similar)
- You may get a confirmation message as you’re exiting BIOS. Read it carefully to make sure you click the correct option to confirm the changes
- Your computer will automatically restart once you exit BIOS
Now you know that a boot sequence is the order in which a computer searches for nonvolatile data storage devices containing program code to load the operating system (OS). Typically, a Windows PC uses BIOS while a Macintosh structure uses ROM to start the boot sequence. We hope this helps.
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