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Old September 23, 2013, 09:42 PM
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For anyone interested here's a cool little article that states RISC vs CISC is almost irrelevant nowadays An Engineer's Options & Futures: Intel x86 Processors ? CISC or RISC? Or both??
If I remember correctly, my computer architecture prof told us that Intel uses CISC on the outside but essentially everything gets boiled down to RISC-like commands within the CPU - kind of what that article is saying. I guess this is similar to using any sort of wrapper class when programming.
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Old September 23, 2013, 10:48 PM
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Originally Posted by Arinoth View Post
A RISC is a Reduced Instruction Set Computer, such as something that has an ARM processor inside, whereas a CISC is a Complex instruction set computer such as an x86 processor.

The good thing about a RISC is that it's designed to do a specific task extremely well, efficiently and low power (if possible). However, it CANNOT do anything aisde what it's designed for (usually, some slight exceptions with hacks and such).
This is incorrect. I believe you're thinking of ASIC. There's nothing inherent about the RISC concept that makes it less capable at general purpose computing.

Google can explain better explain the differences between cisc and risc than any of us. RISC CPUs are more efficient, but CISC was preferable many years ago because it's easier to code in assembly for.

My understanding is that intel x86 CPUs have been risc/cisc hybrids since the Pentium Pro. The advantage to Intel's approach is the massive foundation of x86 code. Despite the inherent inefficiency to its approach, Intel generally maintains superior per-watt performance at most tasks due to superior technology, manufacturing and a better optimized, robust software base. An exception are tablets, for which Intels advantages are not presently relevant.
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Old September 24, 2013, 07:25 AM
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The x86 platform to my knowledge is still considered a CISC architecture whereas an ARM processor is more considered a RISC. Sure x86 might be considered a hybrid, seeing as it took parallel processing from RISCs as they were and still have hit the GHz/speed wall but they are still not optimized for tasks such as RICs are, they are for general computing.

The term "reduced" in that phrase was intended to describe the fact that the amount of work any single instruction accomplishes is reduced—at most a single data memory cycle—compared to the "complex instructions" of CISC CPUs that may require dozens of data memory cycles in order to execute a single instruction
Reduced instruction set computing - Wikipedia, the free encyclopedia

To my knowledge x86 processors tend to take several cycles in order to execute an instruction whereas an arm can fetch/decode/execute potentially in one or two steps. I've never programmed on an x86 that could do that, which is the defining factor of RISC.

This is also what two separate educational establishments have taught to their students, including myself.
Here I am: here I remain

Last edited by Arinoth; September 24, 2013 at 07:32 AM.
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