Just to illustrate what TYPing can do to the map, see this pic of CNEU from my 276C. The width of the part seen is over 10 miles and you can still see all roads.

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And placing of waypoints like this (the light blue is my track) makes it easy to navigate.

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Another "special" with these models is that it is best to have it connected to external power when uploading maps to memory. Running on battery, even fully charged, can result in corrupt maps. I do not know why, it is just well known ...
And give yourself a few hours walking through all menus and all settings, there are a lot of them. It is the engineers gps, for good and bad.