Even if Apple decides to move to ARM on MacBooks, it will have to continue using x86 on its high-end Mac Pro desktops, which are based on Intel's Xeon server chips. That could split the Mac product line, and increase the cost required to support different hardware and software.
Replacing Xeons would be pretty difficult, Gold said. ARM processors are not designed to run high-end applications on Mac desktops.
With laptops and desktops running on different chips, maintaining a full OS for two different architectures could be a nightmare, just as Microsoft may find as it ports the upcoming Windows 8 to ARM, Gold said.
Porting the OS is no trivial issue, but is possible with sufficient testing and redesign, analysts said. Apple shifted from the Power to Intel's x86 architecture, in the middle of the last decade, during which the software transition was smooth, said Roger Kay, president of Endpoint Technologies Associates.
"The transition could be as smooth as the one from Power to x86, which arguably went pretty well," Kay said.
ARM has not expressed interest in the PC market, saying its priority remains in designing low-power processors for mobile devices. But the ARM ecosystem is emerging fast, and it makes sense for ARM to develop high-performance processors to compete with x86, Kay said.
Going by history, Apple doesn't hesitate shifting architectures, and the company would be willing to move to ARM if it can deliver the performance required by Macs, the analysts said.
In September, ARM announced the Cortex-A15 processor design, which will first appear in tablets and smartphones starting in late 2012 or early 2013. The processor, based on a 32-bit design, can run at speeds of up to 2.5GHz and stretch to 16 cores. However, it lacks some capabilities available on x86 chips, such as 64-bit addressing and a large memory ceiling.
If ARM processors are able to cram more CPU and graphics cores to execute
tasks simultaneously, they could outperform x86 chips, said Jim McGregor, chief technology strategist at In-Stat. Future ARM processors will have more cores and higher clock speeds to execute tasks in parallel, McGregor said.
Chip makers such as Nvidia are already showing how dedicated hardware accelerators can take the load from the processor for specific tasks like video decoding.
"They can and are becoming even more parallel and you can fit many more of these cores on a single chip than an x86, or limit the number of cores and run it with much lower power while reducing the cost of the cooling solutions," McGregor said.
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