Muistiliittymä

Muistiliittymä (Finnish for "memory interface") refers to the hardware and protocol that connects a central processing unit (CPU) to the computer system's main memory. The interface defines how data and address information are transmitted between the processor and memory modules, including timing, signal specifications, and bus width. It plays a fundamental role in performance by determining the speed, bandwidth, and latency of memory access.

Typical memory interfaces are built around bus architectures such as the memory bus, front-side bus, or more modern coherent interconnects like Intel's Platform Controller Hub, AMD's Infinity Fabric, or Apple’s M1 memory architecture. A good interface is characterized by high clock rates, low offset between access and response, and efficient use of electrical resources. Modern systems employ synchronous DDR (Double Data Rate) SDRAM, with variants such as DDR3, DDR4, DDR5, and LPDDR standards. Each generation increases density, bandwidth, and power efficiency by altering the electrical timing and signal protocols.

The design of an interface also encompasses memory controller features. These include error detection and correction (EDC) mechanisms like ECC (Error-Correcting Code), dual‑rank or multi‑rank configurations, and special performance modes such as write head or read‑tuning. Many memory controllers are integrated into the CPU die, allowing direct contact without a separate memory controller chip. Some embedded platforms use dedicated memory controllers in the system-on-chip (SoC) area, ensuring low latency for vision or real‑time processing tasks.

In distributed computing and high-performance clusters, memory interfaces also interact via coherent interconnects that allow multiple processors to share a single memory address space. Technologies such as Intel QuickPath Interconnect (QPI), AMD Infinity Fabric, and emerging standards such as HBM (High Bandwidth Memory) and RRAM build upon the core concepts of a memory interface, extending bandwidth while reducing power.