Editing Thread (computing) (section)

=== Single- vs multi-processor systems ===
Until the early 2000s, most desktop computers had only one single-core CPU, with no support for [[hardware thread]]s, although threads were still used on such computers because switching between threads was generally still quicker than full-process [[context switch]]es. In 2002, [[Intel]] added support for [[simultaneous multithreading]] to the [[Pentium&nbsp;4]] processor, under the name ''[[hyper-threading]]''; in 2005, they introduced the dual-core [[Pentium&nbsp;D]] processor and [[AMD]] introduced the dual-core [[Athlon&nbsp;64&nbsp;X2]] processor.

Systems with a single processor generally implement multithreading by [[Preemption (computing)#Time slice|time slicing]]: the [[central processing unit]] (CPU) switches between different ''software threads''. This [[context switch]]ing usually occurs frequently enough that users perceive the threads or tasks as running in parallel (for popular server/desktop operating systems, maximum time slice of a thread, when other threads are waiting, is often limited to 100–200ms). On a [[multiprocessor]] or [[multi-core]] system, multiple threads can execute in [[parallel computing|parallel]], with every processor or core executing a separate thread simultaneously; on a processor or core with ''[[hardware thread]]s'', separate software threads can also be executed concurrently by separate hardware threads.