Mozilla this week said it's unlikely that the final version of Firefox 4 will run on older Macs equipped with PowerPC processors.
"We are not likely to be supporting PowerPC," said Mike Beltzner, director of Firefox, in a message Tuesday on the "mozilla.dev.planning" discussion group. "[But] no announcement has been made yet, as I'd like to have the data to back it up, and am having trouble getting it."
Apple discarded IBM's PowerPC architecture in 2005 when it announced it was shifting to Intel processors. The first Intel Macs launched in January 2006.
Mozilla shipped the fourth Firefox 4 beta two days ago, and has tentatively set a final release for November.
But the beta doesn't work on PowerPC, said one developer, whose report that the browser was "totally broken" on his older Mac prompted Beltzner to confirm that Mozilla might pull support for the processor.
"Firefox should be fast, responsive and secure," said Beltzner in a message posted Wednesday to the same discussion. "We cannot deliver that on PPC [PowerPC] anymore since we don't have support for the JIT on PPC, nor do we have support for OOPP."
Mozilla has not yet spelled out system requirements for Firefox 4. Instead, it directs users to those for Firefox 3.6.
Beltzner said others could build a Mac browser that supports PPC using the Gecko 2.0 engine, the same that powers Firefox 4, probably by disabling the OOPP and JIT code.
One possibility: Camino , an open-source project that develops a Mac-only browser based on Mozilla's Gecko. Camino, which is currently at version 2.0.3, runs on both Intel- and PowerPC-equipped Macs, but relies on the older 1.9 Gecko engine.
Mike Pinkerton, a Google engineer who heads the all-volunteer Camino project, did not reply to questions about the browser's future plans to support PowerPC, but they may be in doubt: Notes for a Wednesday status meeting include the line "Gecko 2.0 [formerly known as] 1.9.3 - on ice."
Earlier this year, Mozilla dropped support for Mac OS X 10.4, aka Tiger, for future versions of Firefox, saying that Firefox 3.6, which launched in January, would be the last to be officially supported on the five-year-old operating system
Apple ceased updating Tiger almost three years ago.
The newest Mac OS, aka Snow Leopard , requires an Intel-based Mac.