George -
It doesn't take much to be an NMRA compliant decoder.
There are only a handful of Mandatory CVs.
? ?1- the primary address
? ? 7 & 8 - the manufacture id
? ? 29 - the configuration data
There are a few "recommended" CVs.
? ? 2 - Vstart
? ? 3 & 4 Acceleration and Deceleration momentum.
? ? 11 - packet time-out value (nothing you'll change)
Everything else is "optional."
I had a locomotive with a Bachmann decoder and it was pretty useless until I replaced it with a more capable decoder.
gs
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