Cpu Glossary

Browse 16 cpu terms defined in plain English, from the cultural dictionary of computing.

16 Cpu Terms

Branch Prediction
A CPU optimization that guesses which way a conditional branch (if/else) will go and speculatively executes that path before the condition is evaluated. If the...
Clock Speed
The frequency at which a processor's internal clock oscillates, measured in hertz (Hz), which determines the rate at which it can execute instructions — though...
Instruction Set
The complete set of machine-level instructions that a CPU can execute, defining the interface between software and hardware. x86, ARM, and RISC-V are...
L1 Cache
The smallest and fastest cache memory embedded directly on each CPU core, typically split into separate instruction (L1i) and data (L1d) caches of 32–64 KB...
L2 Cache
A mid-level CPU cache, typically 256 KB to 1 MB per core, that sits between L1 and L3 in the memory hierarchy with access latencies of roughly 10–20 cycles —...
L3 Cache
The largest on-chip CPU cache, typically 8–64 MB shared across all cores, with access latencies of 30–50 cycles. It acts as the last line of defense before the...
Machine Code
The lowest-level representation of a program — raw binary instructions that a CPU can execute directly without any translation or interpretation.
Machine Instruction
A single binary-encoded operation that a CPU can execute directly, consisting of an opcode and zero or more operands. Each instruction set architecture (x86,...
Memory Alignment
The requirement or practice of placing data in memory at addresses that are multiples of the data type's size (e.g., a 4-byte int at an address divisible by...
Memory Fence
A CPU instruction (also called a memory barrier) that enforces ordering constraints on memory operations, preventing the processor or compiler from reordering...
Mnemonic
A human-readable abbreviation for a machine instruction in assembly language — like MOV, ADD, JMP — making raw CPU operations easier to read and write than raw...
Opcode
Operation code — the numeric portion of a machine language instruction that specifies the operation to perform, such as addition, memory load, or jump.
Performance Counter
A special-purpose register built into the CPU that counts low-level hardware events such as clock cycles, instructions retired, cache hits/misses, and branch...
Program Counter
A CPU register that holds the memory address of the next instruction to be executed. After each instruction fetch, the program counter is automatically...
Register
A small, fast storage location inside a CPU used to hold data currently being processed, such as operands, addresses, or instruction results.
Spectre
A class of hardware vulnerabilities (disclosed January 2018) that exploit speculative execution in modern CPUs to trick a process into leaking data from its...

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