Maps not listed as compatible on my dezl 770

I use Basecamp for Windows when planning our RV summertime trips in the US.  I really like it.  It occurred to me, since I also do a lot of ATV trail riding/exploring, that I could benefit from using my 770 on my ATV.  If I had topo maps compatible with the 770, I could use Basecamp to do the planning and transfer the routes/trails to the 770 for use.

Trouble is, the topo maps listed by Garmin for the NE US do not include the 770 as compatible.  Does anyone know if that is actually true, or ust an oversight on Garmins documentation?  Seems the topo maps include routable roads and such and should work on this device.

Thanks.