A Day For Surprises Astounding Itanium Tricks 4599

And, of course, *this* reminds me.

Back when the Intel Mac was just a rumor, I suggested that, since unlike the Pentium, the Itanium has the ability of being operated in "big-endian" mode, perhaps Apple was going to switch from PowerPC-based Macs to *Itanium-based* Macs!

Well, they didn't do that. Given that parts of OS X are based on BSD, and BSD runs on a variety of systems of both handednesses, perhaps the OS was sufficiently endian-clean that they didn't worry about changes in data formats.

But if the Itanium is much more handy at JIT operation than the x86 architecture - this may not be true; Apple is using one company's amazing JIT technology for the Pentium to enable Power PC apps to run well - then, of course, an Itanium Mac that even included efficient *68K* emulation - yes, include the previous OS as standard on new systems at no extra cost, you guys - would be nice.

However, JIT isn't really all *that* good. Optimizing the plain vanilla load, store, and arithmetic instructions common to all architectures - without revising the hardware to accomodate translate, packed decimal, and so on - gets you good performance most of the time, but it *doesn't* give you the strengths of the real thing. Unlike the Pentium, the Itanium does have *some* supercomputer-like capabilities, such as population count, so perhaps it does come closer. Leaving out the divide instruction, though...

Also, a dual-core CPU *would* lend itself even to high-performance interpretive end of software - and even better JIT end - if there were a mode in which the two cores could be *pipelined* together. Or maybe that's just an OS issue...

John Savard