[yellowapple]

An x86 coprocessor is not that outlandish. Sun offered this with some of their SPARC workstations multiple decades ago, IIRC.

Doing so definitely would be counterproductive for Apple in the short-term, but at the same time might be a reasonable long-term play to get people exposed to and programming against the ARM processor while still being able to use the x86 processor for tasks that haven't yet been ported. Eventually the x86 processor would get sunsetted (or perhaps relegated to an add-on card or somesuch).

[dr_zoidberg]

Either if it's for performance, battery life or cost reasons, it wouldn't really make sense:

a) performance wise, they move would be driven by having a better performing A chip

b) if they aimed at a 15W part battery life would suffer. 6W parts don't deliver good performance.

c) for cost, they'd have to buy the intel processor, and the infrastructure to support it (socket, chipset, heatsink, etc)

Specially for (c), I don't think either Intel would accept selling chips as co-processors (it'd be like admitting their processors aren't good enough to be main processors), nor Apple would put itlsef in a position to adjust the internals of their computers just to acomodate something which they are trying to get away from.

[yellowapple]

> I don't think either Intel would accept selling chips as co-processors

Who said they'd have to be from Intel specifically? AMD makes x86 CPUs, too. Speaking of:

> 6W parts don't deliver good performance.

AMD's APUs have historically been pretty decent performance-wise (relative to Intel alternatives at least), and a 6W dual-core APU is on the horizon: https://www.anandtech.com/show/15554/amd-launches-ultralowpo...

Apple probably doesn't need the integrated GPU, so an AMD-based coprocessor could trim that off for additional power savings (making room in the power budget to re-add hyperthreading or additional cores and/or to bump up the base or burst clock speeds).

> for cost, they'd have to buy the intel processor

Or AMD.

> and the infrastructure to support it (socket, chipset, heatsink, etc)

Laptops (at least the ones as thin as Macbooks) haven't used discrete "sockets"... ever, I'm pretty sure. The vast majority of the time the CPU is soldered directly to the motherboard, and indeed that seems to be the case for the above-linked APU. The heatsink is something that's already needed anyway, and these APUs don't typically need much of it. The chipset's definitely a valid point, but a lot of it can be shaved off by virtue of it being a coprocessor.