Listing of Mac OS versions and builds on computers shipped since 1999

Apple has a handy chart to help you figure out what the earliest version or build number of a particular OS you can install on any given Mac. And it really is handy if you manage an office or lab full of Macs that run off a standardized image. Every time a new Mac arrives, those images need to be updated so that they are capable of booting the newest Mac in the house, while still being backwards compatible. This often involves trickery, hackery and the occasional sacrifice of small furry animals. For most of you this will never be an issue, but we're not all lucky enough to be you. Booting from too early of an OS build, even if it's the same version, can cause unwanted results ranging from inability to boot at all to loud fans raging uncontrollably, displays looking crappy, CD/DVD burners not being recognized or trackpads not working.

In case you were interested, the 3 most recently announced Macs all ship with different Tiger build numbers. The
Power Mac G5 (Late 2005) ships with Mac OS X 10.4.2 build 8E90, the
iMac G5 (iSight) ships with Mac OS X 10.4.2 build 8E102 and the
PowerBook G4 (Double-Layer SD) ships with Mac OS X 10.4.2 8E45. In comparison, my home desktop has a 10.4.2 build number of 8C46 as of the last Software Update. Your build is probably the same if you're running 10.4.2, unless you purchased your computer very recently. To find out which build you're running, click on About This Mac in the Apple menu and then click on the actual OS version number (Version 10.4.2, for example). When you click, it changes to the build number (and if you click again you'll get your serial number).

In theory, the latest build number should be perfectly usable on all prior Macs (provided they are compatible with the OS in the first place). The ability to count past 100 tells us that the new iMac with build 8E102 is going to be the basis for the new image I'll need to prepare this week. I hope your week has more fun in store than mine!