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About Apple Service Diagnostic 3S123
Apple Service Diagnostic (ASD) is distributed to Apple Service Providers. The Apple Service Diagnostic application is designed to run both EFI
and Mac OS X tests from an external USB hard drive. Apple Service Diagnostic (EFI) runs low-level tests of the hardware directly and does not
require Mac OS X, while Apple Service Diagnostic (OS) uses Mac OS X to run tests.

Apple Service Diagnostic version 3S123 Supports the following products:
iMac (20-inch Early 2008)
iMac (24-inch Early 2008)
MacBook (13-inch Early 2008)
MacBook Pro (15-inch Early 2008)
MacBook Pro (17-inch Early 2008)
MacBook Air
Mac Pro (Early 2008)
MacBook (13-inch Late 2007)