Before the 2d Enhanced MIO, MH was using the ADSP-21065L SHARC.
When they designed the 2d card, they chose the ADSP-21364 family that is 5x faster and runs compatible code.
Metric Halo +DSP MIO Tips, Tricks, and Tweaks
Tips, Tricks, Tweaks, for Metric Halo Mobile IO MIO hardware.