Systemminne

Systemminne, or system memory, is the computer’s primary volatile memory used to store data and instructions that the central processing unit (CPU) needs while executing programs. It is faster than non-volatile storage such as hard drives or solid-state drives, and its contents are typically lost when power is removed, making it unsuitable for long-term data retention but essential for fast access during operation.

Hardware and organization: In modern computers systemminne consists of RAM modules mounted on the motherboard and controlled by a memory controller, usually integrated in the CPU or chipset. Memory is organized into banks and channels and is addressed by the operating system through virtual memory. The memory subsystem interacts with the CPU and other subsystems to provide fast, writable storage for active processes and data.

Software and management: The operating system allocates memory to processes and uses virtual memory techniques to create a larger apparent address space. When RAM becomes full, pages can be moved to a swap or page file on slower storage. Memory protection mechanisms isolate processes to prevent unintended access, and the OS may perform memory compaction or compression in some environments.

Types, technology, and capacity: System memory typically refers to DRAM-based RAM, such as DDR3/DDR4/DDR5, with ECC variants used in servers and non-ECC variants common in consumer devices. Modules come in form factors such as DIMMs and SO-DIMMs. Capacities range from a few gigabytes in mobile devices to tens of gigabytes or more in servers, with configurations often tuned for performance and reliability.

Performance and architecture: Memory speed (MT/s), latency, and the number of channels affect bandwidth. Some systems employ non-uniform memory access (NUMA), where memory is connected to different processors. Systemminne is distinct from CPU caches, which are smaller and faster but operate at different levels of the memory hierarchy.

See also: RAM, DRAM, DDR memory, memory controller, virtual memory, paging, ECC, DIMM.