Linked by Thom Holwerda on Thu 28th Jan 2010 20:21 UTC
Hardware, Embedded Systems And yet another item on the iPad? Are we serious? Yes, we are, since this one is about something that even geeks who aren't interested in the iPad itself should find intriguing. Steve Jobs said yesterday that the iPad is powered by an Apple A4 processor, but contrary to what many seem to think - it wasn't designed in-house at all.
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RE[3]: ARM
by lemur2 on Fri 29th Jan 2010 12:34 UTC in reply to "RE[2]: ARM"
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Not necessarily. Remember Transmeta Crusoe?
An ARM is a RISC chip. x86 is CISC, or more accurately these days (Core architecture) a RISC chip with CISC macros. Somebody could create a hardware x86 translater to convert the CISC commands to the RISC commands. Transmeta did the same thing, but in software, that was why it was slow--but the principle was sound. x86 would not be difficult to emulate, you just have to get over the behemoth that is Intel and give people a reason why they'd want x86 compatibility as a secondary function.

A similar type of thing is actually embedded in the Loongson CPU, isn't it?
Loongson 3 adds over 200 new instructions to speed up x86 instruction execution at a cost of 5% of the total die area. The new instructions help QEMU translate x86 instructions by lowering the overhead of executing x86/CISC-style instructions in the MIPS pipeline. With additional improvements in QEMU from ICT, Loongson-3 achieves an average of 70% the performance of executing native binaries while running x86 binaries from nine benchmarks.

Even with 200 extra specialist macro-instructions (hardly RISC-like any more, and coming at a cost of 5% extra die area), Loongson-3 achieves only 70% the native performance when emulating x86.

Without all that extra help embedded in the CPU die, ARM would get nowhere near that. It would be a dog performance-wise when trying to run (emulate) x86 binaries.

Exactly why would anyone want to run x86 binary executables non-natively on ARM at dog-slow performance when there are 20,000+ native ARM packages (which would all work at full CPU performance) for malware-free, zero-cost, full-driver-and-peripheral-support Linux, which cover every conceivable use case for a tablet or a netbook class ARM machine?

Edited 2010-01-29 12:41 UTC

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