Tick–tock model

Tick–tock was a production model adopted in 2007 by chip manufacturer Intel. Under this model, every microarchitecture change (tock) was followed by a die shrink of the process technology (tick). It was replaced by the process–architecture–optimization model, which was announced in 2016 and is like a tick–tock cycle followed by an optimization phase. As a general engineering model, tick–tock is a model that refreshes one side of a binary system each release cycle.

History
Every "tick" represented a shrinking of the process technology of the previous microarchitecture (sometimes introducing new instructions, as with Broadwell, released in late 2014) and every "tock" designated a new microarchitecture. These occurred roughly every year to 18 months. In 2014, Intel created a "tock refresh" of a tock in the form of a smaller update to the microarchitecture not considered a new generation in and of itself.

In March 2016, Intel announced in a Form 10-K report that it deprecated the tick–tock cycle in favor of a three-step process–architecture–optimization model, under which three generations of processors are produced under a single manufacturing process, with the third generation out of three focusing on optimization. The first optimization of the Skylake architecture was Kaby Lake. Intel then announced a second optimization, Coffee Lake, making a total of four generations at 14 nm.

Atom roadmap
With Silvermont Intel tried to start Tick-Tock in Atom architecture but problems with the 10 nm process did not allow to do this. In the table below instead of Tick-Tock steps Process-Architecture-Optimization are used. There is no official confirmation that Intel uses Process-Architecture-Optimization for Atom but it allows us to understand what changes happened in each generation.

Note: There is further the Xeon Phi. It has up to now undergone four development steps with a current top model that got the code name Knights Landing (shortcut: KNL; the predecessor code names all had the leading term Knights in their name) that is derived from the Silvermont architecture as used for the Intel Atom series but realized in a shrunk 14 nm (FinFET) technology. In 2018, Intel announced that Knights Landing and all further Xeon Phi CPU models were discontinued. However, Intel's Sierra Forest and subsequent Atom-based Xeon CPUs are likely a spiritual successor to Xeon Phi.