SL2 I'm surprised that AMD included Intel here.. That doesn't mean that it absolutely can't be done these days. However, I highly doubt that it could be done 20 years ago. Even if it's possible today, there's really no reason to make x86 for phones because the cost for development is too high and there's stiff competition.. ARM does the job perfectly. piloponth There was an initiative from Intel - x86S - scrape all legacy from the ISA and start fresh from x86_amd64. That bavkward compatibiliti down to the 8086 processor is huge in transistors budget. Imagine the x86 become leaner and easier to program for. No transistors allocated for backward compatibility of 30yo old ISAs. Unfortubatelly, Intel scrapped that idea and now we’re in even more deep river of crap called x86 (their little.BIG CPUs for example). FrozenPie1 My guess: Licensing. You can get a license to use ARM in your chip design relatively easy. Try the same for x86, you will be surprised. The ISA is just the "API" so to say the chip is using. The implementation of said functions depends on the chip design itself as long as they can be used the same from the outside and return the expected results. So yes, you could design a highly efficient mobile chip with x86 ISA, it would just be bigger chipsize-wise as x86 has more functions which have to be implemented (no matter if even used on a mobile device or not). aliceif x86 had the disadvantage that it came later to smartphones - but it existed! Asus' early Zenfones ca. 2016 were Intel x86. One of their main problems was that Android apps that used native code (not just bytecode) were impossible to run on them. Now look at why the ARM Windows laptops have such high return rates ... I read "20 years" and I am thinking "What the H is he talking about?". Then it hits me that 20 years ago it was 2005 and I realize that I am old. I hate you! :pIntel was paying to put it's SOCs in phones. No matter the cost of development, if X86 was in smartphones and had a 40+ percent of market share in smartphones, ARM wouldn't be the danger it is today for X86. So it isn't really a matter of money. It's more of a combination of money - the cost of development - and the huge possibility that money to be a total waste. Even if we consider X86 MORE efficient in smartphones than ARM, even if we do that, X86 today on smartphones would be facing the same problems ARM on Windows is facing. Compatibility problems with software that would be a good enough reason to make consumers avoid X86 smartphones.Itanium was expensive and the lack of compatibility was just the perfect excuse to not pay that premium price. Intel was and is a premium brand so they put high prices on the first Itanium chips. AMD offered an alternative option latter, cheap, compatible, highly performant, so Itanium died. If Intel was offering cheap Itanium server chips from the satrt, AMD could be a small ARM designing team today, with it's X86 license expired long ego.AMD and Intel can cover the demand for X86 chips alone. I don't think that it is about licensing and limited number of X86 manufacturers.It wasn't that much latter. Also back then Intel was 1-2 nodes ahead in manufacturing compared to others. It's manufacturing was "alien technology". That advantage gave Intel that chance to compete with ARM SOCs. That advantage plus billions of dollars in manufacturers to build X86 tablets and smartphones. When TSMC managed to catch up with Intel in manufacturing and X86 SOCs lost that advantage, Intel stopped paying to put it's X86 SOCs in smartphones and tablets because it was obvious that ARM had won.ARM Windows laptops have high return rates because of incompatibility. The prices are also too high for new products that try to get into a new market. Qualcomm is also a premium brand, like Intel and Itanium and it is making the same mistake. Premium prices. If I was paying $500 for a top Snapdragon SOC and i was facing incompatibilities, I would probably kept the laptop as second at worst. Paying $1500 and getting worst performance than an $1000 X86 laptop with icing on the cake, incompatibilities, I would also return the laptop.