What happens when your computer starts up? Watch Mac Bowley take you through the components that are involved.
What happens inside your computer from the moment you press the power button? In this step, you’ll learn about the startup sequence. But first, let’s explore the various components involved. The central processing unit or CPU is the brain of your computer, and it controls everything. The CPU is a large chip which reads instructions and data from the computer’s memory. The CPU performs the instructions and writes the data back into your computer’s random access memory or RAM. RAM temporarily stores data while your computer is running. The size of this storage depends on your computer and is measured in gigabytes. For example, your laptop might have something like 4, 6, or 8 gigabytes of RAM.
RAM is fast, and also “read and write”, which means you can add, change and delete the data stored in RAM. RAM is also volatile. Once you power down, you lose all the data stored in RAM. Read only memory, or ROM, is a chip installed and programmed by the manufacturer. You can’t overwrite what’s stored in ROM without risking damage to your computer. Like RAM, the ROM is also fast, but ROM is non-volatile memory, meaning it doesn’t need power to store data, which is the opposite of RAM. The ROM also stores the basic input output system, or BIOS. The BIOS contains all of the basic code for controlling your computer hardware. This includes things like your keyboard, mouse, monitor, and hard drive.
Once the startup sequence is complete, the BIOS does very little as your computer’s operating system takes control. The hard drive, sometimes to the hard disk, is the main storage device in your computer. The hard drive is like RAM, but it is non-volatile and slower. The hard drive stores your computer’s files and folders like your operating system. It stores data on spinning disks and reads it with a mechanical arm. Some computers might have a solid state drive or SSD. These are faster storage devices with no moving parts, which makes them less likely to break. SSDs aren’t as cheap as hard drives yet, but they are becoming more common. So how do these components work together in the startup sequence?
First, your computer CPU starts and fetches instructions from the BIOS stored in your ROM. The BIOS start the monitor and keyboard. It also performs some basic checks to make sure your computer is working properly. For example, it will look for the RAM. The BIOS then starts the boot sequence. It looks for the operating system stored on your hard drive and loads it into the RAM. The BIOS then transfers control to the operating system, and with that, your computer has now completed the startup sequence. Once you know the sequence of events, you can create some really fun lesson plans for your students. Check out the activity and step below and share your own ideas in the comments.