When a new version of the Mac operating system is released, it is designed to work with all Macintosh computers which are shipping at the time. However, when new Macs models are released, they often use hardware, features or "ROM" code which is not compatible with the currently available version of the System software, since the computers were designed after the system software was completed.
To remedy this problem, Apple provides what are called "System Enablers." System Enablers exist to provide support for new computer models when using versions of the Mac OS which were released before the models were finished. They contain the information needed to start up each particular computer. They also provide compatibility between each computer's hardware and the System software. For example, the PowerMac 5400 was released after System 7.5.3, so the standard 7.5.3 System software will not run on this computer. However, Apple provides support for System 7.5.3 on the PowerMac 5400 through the "System Enabler 410" file. This file provides the code necessary for System 7.5.3 to work on this computer.
As each new version of the System software is released, it incorporates all of the support provided by previous System Enablers. For instance, using the PowerMac 5400 example above, Mac OS 7.6 incorporates support for the 5400, so the System Enabler 410 is no longer needed. It is in this way that Apple designs new computers that are compatible with older versions of the Mac OS.
The System Enabler concept started with System 7.1 After the release of System 7.1, each new Mac required a System Enabler. With System 7.5, a supposedly "universal" System Enabler was designed. However, all new computers produced after the release of System 7.5 required a new enabler, because the "universal" enabler was out of date ;-). With the advent of System 7.5.3, this process started anew. On all Mac models introduced before June, 1996, the System 7.5 Update or System 7.5.2 Update acted as a universal "System 7.5.3 Enabler." However, again, since the release of System 7.5.5 Update, Mac OS 7.6, and OS 7.6.1 Update, some of those files are no longer necessary, but other newer ones are! Below is a list of which System Enablers correspond to each Mac model (NOTE: see the "System Versions Compatibility" chapter for information about which models can use which System versions):
Color Classic System Enabler 401 *
IIvi, IIvx System Enabler 001 *
LC III System Enabler 003 *
LC 520, LC 550 System Enabler 403 *
LC 630, Quadra 630, System Enabler 405 *
Performa 630, 635CD
LC 475, 575, Quadra 605 System Enabler 065 *
Centris 610, 650, System Enabler 040 *
Quadra 610, 650, 800
Centris 660AV, System Enabler 088 *
Quadra 660AV, 840AV
Mac TV System Enabler 404 *
Performa 600 System Enabler 304 *
Performa 450, 460, System Enabler 308 *
466, 467
Performa 475, 476, 575, System Enabler 364 *
577, 578
Performa 550, 560 System Enabler 332 *
Performa 5200CD, System Enabler 406 **
LC 5200/75
PM 6100/60, 7100/66, PowerPC Enabler *
8100/80
PM 6100/66, 7100/80, PowerPC Enabler **
8100/100, 8100/110 (requires System 7.5)
Performa 611x Requires System 7.5 *
PM Upgrade Card PowerPC Upgrade Cd Enabler *
PM 7200/75, 7200/90, System Enabler 701 **
7500/100, 8500/120, (requires System 7.5.2)
9500/120, 9500/132
PM 4400/200 System Enabler 827 *****
(does not support OS 7.6)
PM 5400 System Enabler 410 ****
PM/Performa 6400 System Enabler 410 ****
PM 6500 series System Enabler 411 *****
(do not support OS 7.6)
PM 7300 series System Enabler 702 *****
(do not support OS 7.6)
PM 8600/200, 9600/200, System Enabler 702 *****
9600/200MP, 9600/233 (do not support OS 7.6)
PowerBook 150 PowerBook 150 Enabler *
PowerBook 160, 165, System Enabler 131
165c, 180, 180c (replaced System Enabler 111/121)
PowerBook 520, 520c, *
540, 540c
PowerBook Duo 210, 230, PowerBook Duo Enabler ***
250, 270c, 280, 280c
PowerBook 190 PowerBook 5300/190 Enabler **
or
PowerBook 5300/2300/190 Enabler
(requires System 7.5.2)
PowerBook Duo 2300/c PowerBook 2300 Enabler **
or
PowerBook 5300/2300/190 Enabler
(requires System 7.5.2) ***
PowerBook 5300 PowerBook 5300 Enabler **
or
PowerBook 5200/190 Enabler ***
or
PowerBook 5300/2300/190 Enabler
(requires System 7.5.2) ***
PM G3, PowerBook G3 System Enabler 770 Version 1.0 ******
* Under System 7.5 and later, this item is no longer required.
** Under System 7.5.3 and later, this item/items is/are no longer required.
*** Under System 7.5.5 and later, this item is no longer required.
**** Under Mac OS 7.6 and later, this item is no longer required.
***** Under Mac OS 7.6.1 and later, this item is no longer required.
****** Under Mac OS 8.1 and later, this item is no longer required.
System Enabler Notes:
The Power Macintosh 4400/200 ships with System 7.5.3 and requires the above enabler. It
does not support Mac OS 7.6 but does support Mac OS 7.6.1. The enabler is no longer needed
under OS 7.6.1.
The 7300 series, 8600/200, and 9600/200, /200MP and /233 ship with System 7.5.5 and
require the above enabler. They do not support Mac OS 7.6 but do support Mac OS 7.6.1. The
enabler is no longer needed under OS 7.6.1.
The following computers do not require a System Enabler:
