Helion is a single unit of the FemtoStar Helium triple-modular-redundant onboard computer. Helion Modular Development Platform (HMDP) is a modular development platform for the Helion, designed to be connected via a card edge to an external backplane, wherein three HMDPs can operate as a complete Helium system.
Note that this revision of HMDP may differ from the final Helium system in terms of timing, in particular due to the rather simple, non-length-matched breakout to the card edge - this would be relevant at some of the I/O speeds attainable with the ECP5 but is not expected to present a substantial problem at the speeds intended for Helium testing.