ALU
Arithmetic Logic Unit — the part of the processor that performs the basic integer and logic operations: addition, subtraction, comparisons, AND, OR, XOR, bit shifts. One of the most fundamental building blocks in every CPU core.
Role: the ALU is the "calculator" in the core for integers and logic. It takes operands (usually from the register file), performs the operation, and produces the result plus status flags (zero, negative, overflow, carry) that govern subsequent jumps. A modern out-of-order core has several ALUs so that several integer operations can run in parallel each cycle (part of the issue width). Simple operations (add, and) typically take one cycle; more complex ones (multiplication, division) are often handled by separate, specialized units. It differs from the FPU (which does floating-point) — the ALU is for integers and logic. It's so fundamental that it's often the first thing you build when learning digital design. Together with the FPU, load/store units, and SIMD, the ALUs make up the core's execution resources. Related to floating-point unit and register file.