Whilst the idea of
the computer mouse (essentially an inverted trackball) has been around
since the 1960s, many people were still using keyboards as the sole
input method some twenty years on. Even after the mouse became a
standard computer accessory in the mid-1980s, many programs relied on
keyboard shortcuts to perform particular functions.
Even with new input devices, in addition to mice and trackpads, there
is still a place for keyboard shortcuts. In this tutorial, I will show
you the various keyboard key combinations that perform particular tasks
when starting up your Mac.
Keyboard Twister
There’s a joke, at the expense of PC users, that says a PC keyboard only needs three keys: Ctrl, Alt and Delete, this being the key combination required to force-quit rogue programs, to bring up the Close Program dialogue box or to invoke Windows Security.
It’s sometimes known as the three-fingered salute, and
requires the use of both hands to achieve the key combination, given
that the spacing of the keys is such that operation with one hand is
impossible.
Tip:Ctrl-Alt-Delete is not a default keyboard shortcut for anything in Mac OS X. In the Mac OS X Server login screen, however, pressing Ctrl-Option-Delete (the Option key is sometimes marked Alt on a Mac keyboard) will show an alert saying This is not DOS. (Source)
Startup key combinations are invoked immediately following the
startup chime, and before the grey Apple logo appears in the middle of
the screen, when you power-on your Mac.
The object of these key combinations is to perform different
functions, many of which are useful in the maintenance of Macs. The key
combinations listed in this tutorial are specifically for use with Macs
with Intel processors.
Tip: If you have a Windows keyboard, you can usually use the Windows key as the substitute for the Command key on the Mac keyboard.
Tip: If you are having difficulty invoking startup
key combinations, ensure that you press and hold the keys immediately
after the startup chime. Alternatively, use a wired keyboard where
possible, to rule out any issues possible with Bluetooth keyboards.
Available Key Combinations
Boot From External Device
Pressing the C key immediately after the startup
chime will enable the option to boot from a range of media such as a
bootable CD, bootable DVD or a bootable USB drive. This might include OS
X install media (up to OS X 10.7 Lion) or USB install drives that you
have created for other versions of OS X.
Pressing the D key immediately after the startup
chime will boot your Mac into a suite of diagnostic utilities that
enable you to test the hardware of your Mac. This is a useful way to
rule out any hardware issues when trying to diagnose a possible problem
with your Mac (which is why you may not have heard of it and, no doubt,
have never used it!)
Tip: Remember D for Diagnostics.
Reset the PRAM/NVRAM
This one is a bit of a finger-twister and, unless you are more
dextrous than I, you’ll need both hands. The PRAM, on PowerPC Macs, or
NVRAM, as it is on Intel Macs, is the non-volatile (random access)
memory that stores various information about your Mac. This information
includes:
speaker volume
screen resolution
startup disk selection
recent kernel panic information, if any
Resetting the NVRAM, on Intel Macs, may be one way of solving an issue related to the above areas.
When you invoke the Command-Option-P-R keyboard
combination, keep the keys held down immediately after the first startup
chime and release them upon hearing the second startup chime.
Select a Startup Volume (Drive)
Pressing the Option key immediately after the startup chime will show you the available startup volumes.
A startup volume is a hard drive, USB drive, CD or DVD that contains a usable operating system from which the Mac can be booted.
This is particularly useful if you have your hard drive partitioned
with two (or more) operating systems from which you wish to boot your
Mac. Or, in the case of maintenance and recovery, when you need to boot
from an external drive.
Eject a CD or DVD
Pressing the Eject or F12 keys immediately after the startup chime will eject any removable media, such as an optical disc.
This is a useful option on those occasions when you just don’t seem to be able to get OS X to eject a DVD from the SuperDrive.
That said, the reliance on optical media is diminishing now that modern Macs are supplied without a SuperDrive.
NetBoot
Pressing the N key immediately after the startup
chime will allow you to boot the Mac from a compatible network server.
This option is most likely to be used by businesses with a network of
Macs.
Target Disc Mode
Pressing the T key immediately after the startup chime will allow another Mac with a FireWire port (the target Mac) to be used as an external hard drive connected to another Mac (the host).
Target Disk Mode is useful for accessing the contents of a Mac which cannot be booted from its own hard drive.
Safe Boot Mode
Pressing the Shift key immediately after the startup
chime will start up your Mac in a way that performs particular checks
and prevents certain software from automatically loading or opening.
This is particularly useful if any maintenance is required on your
Mac and can be used to resolve or isolate certain problems that exist on
the internal hard drive (startup volume).
Verbose Mode
Pressing the Command-V keys immediately after the startup chime will start up your Mac in verbose mode. Verbose mode is typically used for troubleshooting; it shows what is happening during system startup.
It is possible to start in verbose mode every time you start your Mac, by opening Terminal and entering the following command:
1
sudonvram boot-args="-v&"
To disable verbose mode booting, enter:
1
sudonvram boot-args=
If you just want to boot into verbose mode on an ad-hoc basis simply hold the Command-V keys.
Single-User Mode
Pressing the Command-S keys immediately after the startup chime will start up your Mac in single-user mode.
Single-user mode is a mode in which a multiuser OS X operating system
boots into a single superuser for the purposes of maintenance.
Default Boot Image From a NetBoot Server
Pressing the Option-N keys immediately after the
startup chime will start up your Mac from a NetBoot server using the
default boot image. This is of most use to businesses with a network of
Macs.
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OS X System Recovery
Pressing the Command-R keys immediately after the startup chime will start up from the OS X Recovery System.
The OS X Recovery System is available with all Macs that originally
shipped with OS X 10.7 Lion onwards. That said, the following Macs may
require the download and installation of updated EFI Firmware for these computers to use the OS X Internet Recovery feature:
MacBook Pro (13-inch, Early 2011)
MacBook Pro (15-inch, Early 2011)
MacBook Pro (17-inch, Early 2011)
iMac (21.5-inch, Mid 2011)
iMac (27-inch, Mid 2011)
MacBook (13-inch, Mid 2010)
MacBook Pro (13-inch, Mid 2010)
Mac mini (Mid 2010)
MacBook Pro (15-inch and 17-inch, Mid 2010)
iMac (21.5-inch and 27-inch, Mid 2010)
MacBook Air (11-inch and 13-inch, Late 2010)
The OS X Internet Recovery System allows you to start your Mac
directly from Apple’s servers. Starting up in this way performs a quick
test of your Mac’s memory and hard drive to check for hardware issues.
OS X Internet Recovery can download and start from a Recovery System
image before you are offered the same utilities and options as a local
Recovery System.
Conclusion
In this tutorial I have shown you the different startup key
combinations, and their uses, that are possible with Intel-based Macs.
It is useful to know what these startup key combinations do as they can assist in troubleshooting and maintenance of your Mac.
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