Why Computers Don't Switch Off Like Other Electronic Devices
Several folks have danced around the issue without actually answering it. The reason is straightforward when we turn on a light or a fan or an appliance, we expect it to immediately start working. We expect the same thing when we turn on a computer.
But … A computer has to do a huge amount of stuff before it’s actually considered ‘on’. It needs to sequence a whole bunch of power rails anywhere from 3 to 30, then it might need to do some low-level configuration of basic components, turn on some LED’s, figure out where the keyboard, mouse, and hard drives are attached, and which of them can be loaded. Then it has to verify and load the operating system, enumerate peripherals, establish wireless connections, load drivers, verify and load software, etc. All of these things take a lot of time, and we’re naturally impatient because we are used to ‘on’ being an immediate consequence of flipping a switch like a light.
The Reason Behind Power Management
The reason computers don’t switch off like other electric devices like fans, flashlights, toasters, etc. is because they have a TON more stuff to do besides just get electrons flowing. Most people don't want to wait for that to happen. So, engineers spend huge amounts of time figuring out how to make various things sleep rather than turn off because, well, waking up is usually an easier process than resurrection.
Data Access and Caching
Some of the data on the hard drive is kept in memory to speed up data access. This is generally called caching. However, it means that loss of power can lead to data loss and potentially leave the file system in an inconsistent state.
A Historical Perspective
That was the case earlier. Virtually all micro/home computers like the Commodore 64, Amiga, Spectrum, Enterprise, you name it, had a power switch that instantly cut power from the electronics. There was no shutdown menu.
Even IBM compatibles had usual power switches. The HDD head had to be manually parked, and then we powered down the computer just like any other electronic device.
Later, power management was added, and we ended up with the shutdown menu. The reason for it is no more parking the HDD head but flushing caches and write buffers, save everything that needs to be saved before going down.
Understanding and appreciating the complexity involved in the power cycle of a computer is crucial for maintaining data integrity and ensuring hardware longevity. Whether you're a seasoned professional or a casual user, taking the time to manage your computer’s power states can make a significant difference in your experience. So, always ensure that your computer's systems are properly managed and that you're aware of the implications of shutting down versus logging off.