After using a dual-slot HB 898, the new Helix7 still has me puzzled with only one TINY, TWEEZERS ONLY, COVER MIGHT NOT REMAIN ON chip issue. I use both Navionics and Lakemaster chips. One slot, one map. I think I am right to fish, mark, go home, pull map card, insert any (SanDisk really preferred?) mSD card, export all my data. Did read someplace to never export onto the map chip. Okay, so is the Head gonna save all my data in some endless amount? 1Gb limit? One calendar month? Yikers, dumb here and unaware of how much data the machine will hold before overwriting. Is there a warning screen that my 7 is full and time to offload? Must have a ripped out page in my online manual....