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A single-core processor is a microprocessor with a single core on a chip, running a single thread at any one time. The term became common after the emergence of multi-core processors (which have several independent processors on a single chip) to distinguish non-multi-core designs. For example, Intel released a Core 2 Solo and Core 2 Duo, and one would refer to the former as the 'single-core' variant. Most microprocessors prior to the multi-core era are single-core. The class of many-core processors follows on from multi-core, in a progression showing increasing parallelism over time.

Processors remained single-core until it was impossible to achieve performance gains from the increased clock speed and transistor count allowed by Moore's law (there were diminishing returns to increasing the depth of a pipeline, increasing CPU cache sizes, or adding execution units).[1]

Increasing parallel trend[edit]

  • Single-core – one processor on a die. Since about 2012, even most smartphone CPUs marketed are no longer single-core; Microcontrollers are still single-core, while there are exceptions.
  • Multi-core – a 'few' processors on a die, e.g. 2, 4, 8.
  • Many-core – a 'large number' of processors on a die, e.g. 10s, 100s, 1000s. Some specialist ASICs/Accelerators and GPUs fall into this category.


  1. ^ "architecting solutions of the manycore era". 19 February 2010.