The NXP MIMXRT1021DAG5A is a crossover MCU built around a 500 MHz ARM Cortex-M7 single-core processor — fast enough to handle real-time control loops alongside Ethernet and USB OTG protocol stacks without a separate application processor. On-chip RAM is 256K x 8, so code and large data buffers live in external memory; the part boots from external Flash via the EBI/EMI interface.
500 MHz — what it buys you on the bus
The Cortex-M7 core runs at 500 MHz. The 256K x 8 internal RAM is tight for a full TCP/IP stack plus application buffers.