Fundamentally, what is a PC architecture, what is the difference between x64, x86, ARM, whatever else etc. and why do they offer different benefits or drawbacks or performances
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* x86 is short for 80×86 and it refers to the architecture developed by Intel for their 16bit and 32bit processors.
* x64 (more properly “AMD x86-64”) is the 64bit version of above, but developed by AMD. This was because Intel had decided to abandon the x86 architecture for Itanium. This was a disaster. AMD ate Intels lunch for YEARS in the 2000s over this misstep. Intel had to license AMD x86-64 from them.
* ARM is a processor that has roots in the old Apple 2/Commodore days. It is a simpler design. It offers fewer instructions, but runs them faster. They are built to run cooler, use less energy, and to be less expensive. This is why they are so popular in mobile devices. ARM does not make the processors, but licenses the design to Apple, Qualcomm, Samsung, nVidia, etc. There are 32bit and 64bit versions.
As for bits, this is this size of the register and (in most cases) the memory address size. The 8086 for example was an 16bit processor. All of the internal registers (temporary storage locations inside the processor) were 16bits wide and read memory 16bits at a time. The 8086, however, had a 20bit memory address bus. This allowed it to read up to 1MB of RAM/ROM instead of 65k…but still 16bits at a time. Starting with the 80386, Intel used 32bit registers and could address 4GB of RAM. AMD came out with AMD x86-64 and released the first Opteron in 2004. It can address 18 Exabytes of RAM (18,000 Petabytes, 18,000,000 Terabytes, 18,000,000,000 Gigabytes). While I think IBM and others might be messing around with 128bit processors, it does not seem necessary at the moment.
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