The Ethos-U55 is designed as a neural network accelerator for microcontrollers. The combination of Ethos-U55 and Cortex-M55 can provide a 480x improvement in machine learning performance, ARM reckons.
The Ethos-U55 joins the Ethos-N77, the Ethos-N57 and Ethos-N37 in the NPU family. Presumably ARM will also supply 'P' prefixed NPUs.
The Cortex-M55 is intended as a stand-alone microcontroller processor that can do all the conventional functions of an MCU but with enhanced support for processing artificial neural network maths and providing about a 15x performance boost. This comes from the inclusion of ARM's Helium technology, which provides support for vector maths.
Arm Helium technology is the M-Profile Vector Extension (MVE) for the Arm Cortex-M processor series. Helium is an extension of the Armv8.1-M architecture and delivers a performance uplift for machine learning (ML) and DSP applications. The Cortex-M55 processor is the first Arm processor to support Helium.