Unbuffered

Unbuffered refers to an operation or device that processes data without intermediate storage or queuing. In computing and hardware, unbuffered means data flows directly from source to destination with little or no buffering by the system. The term is commonly contrasted with buffered, line-buffered, or fully buffered arrangements, where data is collected and released in larger chunks.

In input/output I/O, unbuffered means each read or write request is sent to the device immediately rather than being accumulated in memory. This reduces latency and provides faster visibility of results but increases the number of system calls and can reduce throughput. Applications that require real-time response, interactive use, or streaming diagnostics may use unbuffered I/O. In many languages and systems, unbuffered I/O can be configured by flags or modes, such as setvbuf in C with _IONBF, Python open with an unbuffered mode, or wrappers that adjust buffering behavior.

In computer hardware, unbuffered memory refers to DRAM modules without an external register or buffer between the memory controller and the memory chips. Unbuffered DIMMs are common in desktops and laptops, while registered or buffered DIMMs add a buffer to improve stability and scalability in servers. The choice affects memory timing, capacity limits, and error handling; unbuffered memory generally offers lower latency but less signaling robustness at high densities.

The term also applies to data streams and software libraries that disable internal buffering to ensure immediate output, such as logging or real-time monitoring. Some programs provide command-line options to disable buffering or to set buffer sizes.