Have you met any of these little problems? 】
System does not start properly ...
Connection projector does not display properly ...
Long time not shutdown of the Apple Computer, boot black screen ...
These problems can be caused by some of the configuration files stored in Apple's system memory.
"Official statement"(must be read by studious)
NVRAM (non-volatile random access memory) is a small amount of memory that the MAC uses to store certain settings and quickly access them. Settings that can be stored in NVRAM include volume, display resolution, Startup Disk selection, time zone, and recent kernel crash information. The settings stored in NVRAM depend on your Mac and the devices that are used with that Mac.
Resetting NVRAM may be helpful if you experience problems with these settings or other settings. For example, you might need to reset NVRAM if your Mac is not booting from a disk selected in Startup Disk preferences, or if you briefly display a question mark icon before your Mac starts up.
"Solution"
1. Turn off your MAC
2. Press and hold the following four keys immediately after pressing the power button: Option, Command, P, and R
650) this.width=650; "class=" Confluence-embedded-image confluence-external-resource "alt=" Option "width=" "src = "https://support.apple.com/library/content/dam/edam/applecare/images/en_US/keyboards/ Macos-nvram-option-key.png "style=" margin:0px 2px;padding:0px;border:0px;/>650) this.width=650; "class=" Confluence-embedded-image confluence-external-resource "width=" src= "https://" Support.apple.com/library/content/dam/edam/applecare/images/en_us/keyboards/mac-nvram-add-icon.png "Style=" margin:0px 2px;padding:0px;border:0px; "alt=" Mac-nvram-add-icon.png "/>650) this.width=650; "class=" Confluence-embedded-image confluence-external-resource "alt=" Command "width=" 95 " Src= "https://support.apple.com/library/content/dam/edam/applecare/images/en_US/keyboards/ Macos-nvram-command-key.png "style=" margin:0px 2px;padding:0px;border:0px;/>650) this.width=650; "class=" Confluence-embedded-image confluence-external-resource "width=" src= "https://" Support.apple.com/library/content/dam/edam/applecare/images/en_us/keyboards/mac-nvram-add-icon.png "Style=" margin:0px 2px;padding:0px;border:0px; "alt=" Mac-nvram-add-icon.png "/>650) this.width=650; "class=" Confluence-embedded-image confluence-external-resource "alt=" P "width=" "src=" Https://support.apple.com/library/content/dam/edam/applecare/images/en_US/keyboards/macos-nvram-p-key.png " style= "margin:0px 2px;padding:0px;border:0px;"/>650) this.width=650; "class=" Confluence-embedded-image confluence-external-resource "width=" src= "https://" Support.apple.com/library/content/dam/edam/applecare/images/en_us/keyboards/mac-nvram-add-icon.png "Style=" margin:0px 2px;padding:0px;border:0px; "alt=" Mac-nvram-add-icon.png "/>650) this.width=650; "class=" Confluence-embedded-image confluence-external-resource "alt=" R "width=" "src=" Https://support.apple.com/library/content/dam/edam/applecare/images/en_US/keyboards/macos-nvram-r-key.png " style= "margin:0px 2px;padding:0px;border:0px;"/>
3. Hold down the above four keys for about 20 seconds, during which your Mac may appear to be restarting. (If your Mac is powering on when it's turned on, you can release the keys after your Mac beeps two times .) )
After your Mac finishes booting, you may need to turn on system preferences and adjust the settings that have been reset, such as volume, display resolution, Startup Disk selection, or time zone.
This article is from "Happy to share" blog, please be sure to keep this source http://2984407.blog.51cto.com/2974407/1929987
One key to the Apple computer's little problems!