System Management Controller: Difference between revisions

Revision as of 16:58, 9 December 2006

Latest revision as of 01:11, 6 May 2025

(96 intermediate revisions by 66 users not shown)

Line 1:

The '''System Management Controller''' ('''SMC''') is a subsystem of [[Intel]] [[Macintosh]] computers. It is similar in function to the older [[System Management Unit|SMU]] or [[Power Management Unit|PMU]] of PowerPC based Macintosh computers.<ref>{{cite web |title=HT2368: About the SMC Firmware Updates |url=http://support.apple.com:80/kb/HT2368?viewlocale=en_US |website=Official Apple Support |archiveurl=https://web.archive.org/web/20081223202919/http://support.apple.com/kb/HT2368?viewlocale=en_US |archivedate=2008-12-23 |url-status=dead }}</ref><ref>{{cite web |title=HT202040: About the SMC Firmware Updates |url=https://support.apple.com/en-us/HT202040 |website=Official Apple Support |publisher= |accessdate=2018-04-28 |archive-date=2021-05-19 |archive-url=https://web.archive.org/web/20210519004618/https://support.apple.com/en-us/HT202040 |url-status=live }}</ref>

The '''SMC''' is an internal sub system introduced by [[Apple]] with the introduction of their new [[Intel]] processor based machines in 2006. It takes over the functions of the [[SMU]]<ref>[http://docs.info.apple.com/article.html?artnum=303725 Apple general documentation on SMC Updates]</ref>. Apple has released updates for this system in order to address power or sleep issues in several resent models <ref>[http://search.info.apple.com/index.html?search=Go&lr=lang_en&kword=&khot%20OR%20kcap&news&q=SMC%20update&&type=kbdload Search of SMC Updates on Apple's knowledge base]</ref>.

==Overview==

The SMC has roles in controlling thermal and power management, battery charging, video mode switching, [[sleep mode|sleep and wake]], [[hibernation (computing)|hibernation]], and [[light-emitting diode|LED]] indicators. It also enables enforcement of the [[macOS]] [[End-user license agreement|End User License]], allowing macOS to identify when it is running on non-Apple hardware.<ref>{{cite podcast |host=[[Randal L. Schwartz|Randal Schwartz]] |date=2010-08-11 |df=mdy |title=VirtualBox |url=https://twit.tv/shows/floss-weekly/episodes/130 |website=[[FLOSS Weekly]] |series=130 |publisher=[[TWiT.tv]] |accessdate=2018-04-28 |archive-date=2018-04-28 |archive-url=https://web.archive.org/web/20180428181223/https://twit.tv/shows/floss-weekly/episodes/130 |url-status=live }}</ref>

The SMC like the SMU before it controls power flow and fan speed. The main objective is to keep the machine running normally with a minimum of noise.

The SMC should not normally need to be reset at all. Doing so however can be useful in [[troubleshooting]] certain issues.

*Failure to turn on

*Failure to recognize internal [[Airport Extreme]] card

*Failure to recognize attached devices (Firewire, USB, etc.)

*Unexpected power off (i.e., sudden unexpected loss of power, not system shutdown)

*Failure to wake from sleep or unexpected sleep (note this can also be caused by [[operating system]] corruption)

This is due to the fact the SMC may become corrupted over time and not respond properly to certain requests. This sort of corruption can be triggered by a power surge.

==See also==

== Current SMC Updates ==

* [[Embedded controller]] (EC)

{| class="wikitable"

* [[Power management integrated circuit]] (PMIC)

|-

* [[Power Management Unit]] (PMU)

!

* [[System Management Unit]] (SMU)

! Shipping Version

* [[Apple T2]]

! Updated Version

|-

| [[iMac]] Early 2006

| ?

| [http://www.apple.com/support/downloads/imacearly2006smcfirmwareupdate.html 1.1f5]

|-

| [[Mac Mini]] Early 2006

| ?

| [http://www.apple.com/support/downloads/macminiearly2006smcfirmwareupdate.html 1.3f4]

|-

| [[MacBook]] Any

| ?

| [http://www.apple.com/support/downloads/macbooksmcfirmwareupdate11.html 1.4f12]

|-

| [[MacBookPro|MacBook Pro]] 15-inch

| ?

| [http://www.apple.com/support/downloads/macbookpro15inchsmcfirmwareupdate.html 1.2f10]

|-

| [[MacBookPro|MacBook Pro]] 17-inch

| ?

| [http://www.apple.com/support/downloads/macbookpro17inchsmcfirmwareupdate.html 1.5f10]

|}

==References==

{{Mac-stub}}

{{reflist}}

==External links==

{{step|[[System_management_unit|SMU]]|}}

*[https://support.apple.com/kb/HT201518 EFI and SMC firmware updates for Intel-based Macs]

[[Category:Products introduced in 2006]]

==Notes==

<references/>

[[Category:Lists of three-character combinations]]

[[Category:Macintosh computers]]

[[Category:Apple ComputerInc. hardware]]