Your computer POSTs every time you use it, but what is the POST and why is it important?
Your computer does a thousand-and-one things before you even start using it. One task that it does at startup is something called POST or (Power-On Self Test). Even though this is happening behind the curtains, it’s still an immensely important process. Here’s an explanation of what POST is and why it’s important.
What Does POST Mean?
POST stands for Power-On Self Test. As the name suggests, it’s a process that occurs when the computer is powered on. When your computer first turns on, the first thing that actually initiates is the system’s BIOS. This stands for Basic Input/Output System. The BIOS is a bit of software that resides in a chip on the motherboard. It does a lot for your computer
How Is the POST Performed?
When the computer is turned on, the BIOS performs the POST by checking if the hardware components are working properly. It will target the chips on the motherboard like the RAM, video card, CPU, etc. It also checks the mouse and keyboard, which is why these devices light up when the computer is turned on.
If everything is in order, the startup process will then begin as normal. Since the BIOS lives on its own chip, it doesn’t rely on the operating system to function. Indeed, the BIOS actually begins before the operating system is even loaded.
Why Is the POST Important?
When you turn on your computer, you want to make sure that all of the components are working properly before the operating system tries to load. That’s why the BIOS stops the startup process when there’s an error. This is important because a lot of crucial programs are being loaded when the computer starts up. Having faulty chips or a faulty power supply might poorly impact that process and lead to more issues. There could also be other reasons why your computer is not booting.
POST Errors and Beep Codes
Your computer will indicate the POST status with certain beeps. If the POST goes through without a hitch, you will typically get one beep followed by your operating system starting up. However, if the POST is not successful, your system will notify you in the form of a combination of beeps.
There are a handful of different beep combinations (beep codes) that occur during startup. These point to different errors during the POST process. Unfortunately, beep codes can differ from company to company, as there isn’t a standard for them. There are, however, a set of common beep codes that are on most systems.
|Normal POST, no error||1 short beep|
|Display Adaptor error||1 long beep, then 2 short beeps|
|Enhanced Graphics Adaptor error||1 long beep, then 3 short beeps|
|Keyboard card error||3 long beeps|
|POST error||2 short beeps|
|Power supply, system board, or maybe RAM problem, keyboard problem||Continuous beep|
|Power supply, system board problem, disconnected CPU, or disconnected speaker||No beep|
|Power supply or system board problem or keyboard||Repeating short beeps|
|System Board Problem||1 long beep, then 1 short beep|
These beep codes aren’t going to be the same for every computer, so it’s important to look up the beep codes for your computer.
The Little Things are Always the Most Important
The POST process happens within the first couple of seconds during startup, but it’s one of the most important. It alerts you if there are any hardware issues you need to know about before the computer starts up. The POST process has probably saved you from computer errors, and you may not have even noticed. It’s been a saving grace for computers in the past and continues to this day.
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