Troubleshoot Mac boot slow command +option + P + R

Mac What happens when the boot slows down?

Command + option + P + R

The key is to press the 4 key after the boot has not been heard 3 sound screen appeared gray and gray several times

Boot Speed 5s

The method of resetting the pram and NVRAM is to press and hold command, option, p, and r four keys after the system starts up to the gray screen and turn the halo, and then turn the screen from black to gray two or three times, or start the stereo over two or three times, Or the computer's white power led flashes two or three times before letting go. However, there are two options for this combination in terms of specific use. One is to turn off the computer first, then press the power switch to start the PC, and press and hold the four keys. The other is to select or force a restart when the system is not powered down, and then press and hold the four keys. The first method resets the NVRAM including pram, while the second one resets only the rest of the Pram,nvram is not involved.

NVRAM vs PRAM

• Mac users often hear some troubleshooting steps such as resetting the parameter cache, resetting the NVRAM, holding down command+option+p+r, and so on, which involve some confusing concepts, including NVRAM and pram.

NVRAM (Non-volatile RAM) is not Apple's original term. Refers to a kind of static memory that stores data when the computer shuts down or loses power, and continues to maintain its content memory after a shutdown. This storage can rely on spare or extra batteries to retain its contents to provide pre-set data for the machine's start-up.

PRAM (Parameter RAM), also known as the parameter cache, is the term used by Apple itself. Essentially, it is equivalent to the CMOS on the PC and the NVRAM on the SPARC workstation. In other words, it is a small part of the NVRAM, which relies on battery power and real-time clock in the same chip memory. Years ago, Apple defined Pram's top 20byte content, and its remaining space became Xpram (extended pram) dedicated to Mac OS. After the adoption of PCI, the pram capacity of the Apple machine increased, and this expansion after the pram is simply called NVRAM, which contains different areas of storage expansion Pram,open firmware parameters and the Macintosh name registry. From another point of view, pram is a small part of the NVRAM.

The contents of the data stored in NVRAM and pram vary depending on the model and operating system content. On PowerMac architectures, the content is much more than the Intel architecture. At the beginning of the advent of the Intel architecture computer, the NVRAM was almost empty (at least, I checked it 1.5 ago). And now there's something in the NVRAM in the Intel-architected computer.

The information provided by Apple's knowledge base is stale. Resetting your Mac's PRAM and Nvram says PRAM's content includes: AppleTalk status, Series port settings and port definitions, warning clock settings, app fonts, series printer locations, AutoKey rate, autokey delay, Speaker volume, beep, double-click Reaction time, embedded point rate, mouse speed, boot disk, menu flicker value, display depth, 32-bit address, virtual memory, RAM disk, and disk cache. Note: This article was last updated in May 2007, and the hardware involved included Powerbook, Powerbook G3, Powerbook G4, IBook, IBook G4, imac, imac (Slot loading), PowerMac G3, PowerMac G4, PowerMac G5 and Xserve. Does not include any Intel-architected computers.

and Mac OS X:what's stored in PRAM? A text called PRAM includes: monitor and video settings, time zone settings, start volume, speaker volume, recent kernel panic messages and DVD region code settings. This article was last updated in November 2004 for Mac OS X 10.1 to 10.3 (at that time 10.4 is not available).

And each user's own pram or NVRAM is what content, you can use the Terminal command NVRAM to view. To do this, open the terminal (Terminal) from within the utilities (Utilities) folder under the application (applications), and then enter:

Nvram-p Enter

Using the man command to see an explanation of the NVRAM, you will find that the command is used to process the firmware (firmware) NVRAM parameter. The concept of firmware has already been described in the previous article, which is not mentioned here.

Understanding the meaning of NVRAM and pram is more than a fail-clean for end users. Some computer malfunctions, such as the external/internal disk does not display, the presence of four languages, etc., or can be restored by resetting pram or NVRAM. Objectively speaking, after resetting the pram or NVRAM, the parameters in the pram or nvram revert to the machine factory values, which in itself does not help the user to find the cause of the previous failure, but once the failure is due to incorrect firmware or parameter values, resetting these parameters can help users to restore the system in a timely manner.

The method of resetting the pram and NVRAM is to press and hold command, option, p, and r four keys after the system starts up to the gray screen and turn the halo, and then turn the screen from black to gray two or three times, or start the stereo over two or three times, Or the computer's white power led flashes two or three times before letting go. However, there are two options for this combination in terms of specific use. One is to turn off the computer first, then press the power switch to start the PC, and press and hold the four keys. The other is to select or force a restart when the system is not powered down, and then press and hold the four keys. The first method resets the NVRAM including pram, while the second one resets only the rest of the Pram,nvram is not involved.

In the case of a PowerMac frame model, you can use the Open Firmware (Open Firmware) interface to reset the NVRAM in another way, which is to press command, option, O, and F on startup, and the screen turns black and displays white lettering. After the cursor pauses, enter: Reset-nvram return. Then enter: Reset-all Enter, the system is automatically re-up.

Some Mac users may feel that their Mac in the use of a period of time, the boot has become more and more slow, how can we optimize the speed of the Mac boot, the following small series to you recommend the following 6 to optimize the Mac boot speed of the small tips, hope to help everyone.

　　First, try to delete the desktop file

Each time the Mac starts, it indexes the contents of the desktop, creating a thumbnail icon (thumbnail icons) for each file on the desktop, and so on.

Therefore, it is recommended that you can put the files on the desktop as far as possible into the appropriate folders, categorized. One to speed up the boot speed, and also more organized.

Second, Remove boot loader

System Preferences in the user settings can be removed some of the unused Boot program (System Preferences and user Accounts) you just need to put the hooks in front of those programs (such as ichat). With the Activity Monitor program, you can see a list of running programs in the background.

This for me, is a habit, usually have the software after the new installation requirements to check for updates at startup, I will generally click No.

　Third, Disabled Dashboard

If you use it frequently, dashboard is good. However, you should also be aware that each widgets and web clips are very memory and resource-conscious. How to prohibit? Method is also very simple.

Open the terminal and typed the following command:

Defaults write Com.apple.dashboard Mcx-disabled-boolean YES

Then you can restart the MacBook or typing the following command:

Killall Dock

When you need to dashboard again, the following commands can be reversed:

Defaults write Com.apple.dashboard Mcx-disabled-boolean NO

Restart or typing:

Killall Dock

If you start or close dashboard do not successfully try to repeat it again generally OK

　Iv. Clearance PRAM ( for Intel's Apple computers only )

This method is not a fundamental workaround, but some unnecessary boot settings can be removed. Thus, time is also saved. To do this: restart your computer and press COMMAND + OPTION + P + r until you hear the 3 to 4 sound start ring.

　v. Clear PMU (IMac not available ) , for MacBook, MacBook Pro user, by:

1. Make sure the MacBook is off.

2. Remove the power adapter and battery.

3. Press the power switch and hold for 5 seconds to release.

4. Connect the power adapter and battery.

5. Turn on the power switch.

For MacBook Air users, the method is:

1. Ensure air shutdown status

2. Connect the power adapter to the operating power supply.

3. Press the (left) shift-control-option at the same time to press the power switch. (Remember to use the left shift and other keys)

4. Wait 5 minutes, press the power switch to restart the Macbook Air.

　　vi. prohibition of useless system options .

If you do not use Wireless (wireless internet), Bluetooth (Bluetooth), Speech recognition (speech recognition) or Internet sharing (shared), then, very simply, turn them off!

Troubleshoot Mac boot slow command +option + P + R