x86-64 — the 64-bit world

x86-64 (also called x64, amd64, or intel 64) is the 64-bit evolution of x86. here's the plot twist: amd designed it, not intel. amd created amd64 in 2003, and intel was forced to adopt it (calling it intel 64 / em64t). this is why you see "amd64" in linux packages even on intel cpus.

analogy: x86 → x64 is like upgrading from a 4-lane highway (32-bit) to a 16-lane superhighway (64-bit). same road rules (backward compatible), but way more capacity.

the big upgrades: registers doubled from 8 to 16 and widened to 64 bits, addressable memory jumped from 4 gb to a theoretical 16 exabytes, and it added new instructions like sse2 mandatory support. crucially, it runs old 32-bit x86 code natively.

64-bit register set (expanded)

try it — click any instruction

arm — efficiency king

arm is a risc (reduced instruction set computer) architecture. unlike cisc, each instruction does one simple thing — but does it blazingly fast. arm doesn't manufacture chips itself; it licenses the design to companies like apple, qualcomm, samsung, and mediatek.

analogy: if cisc (x86) is a swiss army knife, arm (risc) is a set of sharp, specialized tools. each tool does one thing perfectly. you need more steps to complete a task, but each step is lightning-fast.

arm's killer feature is power efficiency. fixed-length 32-bit instructions make the decoder simple and energy-cheap. the latest armv9 powers everything from ₹500 microcontrollers to apple's m4 chip that beats many intel desktop processors.

pipeline (classic 3-stage)

try it — click any instruction

risc-v — the linux of cpu architectures

risc-v (pronounced "risk-five") is an open-source, royalty-free instruction set architecture. unlike arm (you pay licensing fees) or x86 (proprietary to intel/amd), anyone can build a risc-v chip without paying a penny. born at uc berkeley in 2010.

analogy: arm is like android (open-ish, but google controls it). risc-v is like a truly open linux kernel — anyone can fork it, modify it, and build custom silicon with zero licensing fees.

the design is modular. the base integer isa (rv32i/rv64i) is tiny — only 47 instructions. then you add extensions like a plugin system. you pick exactly what you need.

modular extension system

try it — click any instruction

amd — the company that shaped the architecture

important distinction: amd is a company, not a cpu architecture. but it has hugely influenced cpu architecture history. amd makes chips that use the x86 and x86-64 instruction sets.

analogy: think of x86 as a language. both intel and amd "speak" x86, but with different accents (microarchitectures). amd's zen accent turned out to be incredibly good.

amd's biggest flex: they invented amd64 (x86-64) — the 64-bit extension that every modern pc uses. intel tried their own 64-bit (itanium/ia-64) and it flopped. intel had to license amd's design. also, amd's zen architecture (2017–present) ended intel's decade-long monopoly.

architecture timeline

both intel and amd make x86-64 chips, but the internal microarchitecture is completely different. amd went fabless and uses tsmc. amd's chiplet design (multiple small dies connected together) was a breakthrough — cheaper to manufacture, better yields, and easier to scale.

your lenovo loq with rtx 3050 runs the x86-64 instruction set. the performance difference between amd and intel comes from the microarchitecture underneath, not the isa.

comparison table

tl;dr: x86 = old 32-bit standard. x64 = modern 64-bit (what your pc runs). arm = power-efficient, rules mobile and is taking over laptops. risc-v = the open-source future. amd = the company that made x64 possible and competes with intel.