The Motorola X8 is rumoured to be what will power the shortly-to-be-revealed Google/Motorola smartphone, the Moto X. Despite the name the X8 isn't actually an 8-core System on Chip (SoC) but a collection of customised components, including an SoC, in an "intelligent" optimised configuration. These components include a custom Qualcomm Snapdragon S4 Pro SoC including its CPU and GPU cores and two Digital Signal Processors (DSPs).
In an interview with PC Mag Motorola's VP of engineering, Iqbal Arshad, said the 'X8 mobile computing system' moves away from the CPU based architecture to do "intelligent, probabilistic computing". He said that Motorola has worked on the Qualcomm S4 Pro's firmware to optimise it in several ways to offer "best-in-class performance".
Arshad went on to talk about the parts of the 'mobile computing system' making up the X8 outside the Qualcomm SoC. Referring to the DSPs, he said these extra components comprise a "contextual computing processor" and a "natural language processor." The contextual processor handles the sensors, display and touch interaction and works as the primary processor when the device is in standby. The natural language chip handles several audio functions.
This information makes me think about the touted Moto X functionality; always being ready to listen to voice commands even when untouched in a standby state. It is confirmed that the X8 powers the new Droid Ultra, Droid Mini, and Droid Maxx smartphones. PCMag has a hands-on with those new droids you can read through here.
Motorola's engineering VP went on to talk about his company's expertise in DSP design (I remember owning an Atari Falcon with a built-in MC56001 DSP clocked at 32 MHz). He said that without the custom DSPs the X8 devices "would need two additional batteries". It isn't all about battery stamina though as Motorola also claim this 'X8 mobile computing system' can perform better than the competition too.
Turning to economic and business aspects of the design Arshad added that keeping the custom logic separate from the main SoC will allow Motorola to change away from Qualcomm Snapdragon processors without too much difficulty should such a move prove beneficial.