The HMPU is a Motorola 68020-based processor used in LCN nodes prior to the introduction of the K2LCN and K4LCN processors.

In addition to the 68020 processor, the HMPU board contains floating point calculation hardware and 2 MW of memory. This processor can be used in place of the HPK2-2.

This processor is required for the early configuration of a redundant AM.

This processor no longer in widespread use, having been replaced by the K4LCN-4, K4LCN-8, and K4LCN-16 in most current LCN systems.