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Dakota 20 - topo 100k software? how does expandable memory work?

Started by MAT, April 13, 2011, 05:23:24 AM

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MAT

Just bought a Dakota 20, my first Garmin after 2 Magellan GPS's so I'm not familiar with them.  With the Topo 100k maps, can you just load a region (part of the map), or do you have to load the entire map?  If you can load a specific area I take it you can do that with basecamp, or does Topo 100k come with software (like Magellan Mapsend Topo)?  Odd but I have not seen anything that says you can do this and how.  Also is the micro SD card an expandable memory or is it like a separate drive?  In other words, if the topo maps are 3.2 gb and I add a 3.0 gb card is that all I need?  Thanks.

Boyd

This gets more complicated than you might think.  :-\

If you buy the DVD version of the 100k topo, you cannot load the entire US on your Dakota, regardless of how big a card you have. The mapset is a little under 3GB, but it is divided into about 6,600 segments (tiles) and the Dakota has a limit of about 4,000 segments. So your could choose a section of the US, up to the 4,000 segment limit and send it to either internal memory or a card. They are treated as separate drives, so a single file cannot span them both.

Yes, you could use either Basecamp/Mapinstall or Mapsource to select the area you want and send it to the GPS.

If you really want the entire US, purchase the pre-loaded card. It is divided into much large segments, and the whole US fits in under 500. Note that the segment limit applies to all maps on the device, so if you max it out to 4,000 with the DVD version, you can't load any additional maps, regardless of how much space is left on the memory card. The preloaded card leaves you plenty of segments to load additional maps, but they would have to fit into internal memory because you can't add maps to the preloaded card. But it is "plug and play" - pop the card into the unit and start using it.

There is also a download version of the 100k topo. Not sure about this, I suspect it only uses 500 segments but don't really know.

Indrid Cold

Quote from: Boyd on April 13, 2011, 07:31:46 AM

There is also a download version of the 100k topo. Not sure about this, I suspect it only uses 500 segments but don't really know.
The downloadable one can fit on a 4GB card but will be locked to the GPS, so getting a pre programmed card from REI or another vendor is more versatile.

MAT

Quote from: Boyd on April 13, 2011, 07:31:46 AM
This gets more complicated than you might think.  :-\

Isn't that always the case!  It's the little things you don't know that REALLY matter. :o

I don't need to load the entire US so that's fine.  Also I was trying to see if a regional 100K would be better than the full US if that would use up all the memory.  I like the 100k as a base map for traveling, then I'll get the 24K or air photos for my destination.  I'm not sure what constitutes a map "segment" but I suppose I'll figure that out when I try to load these things? 

maps4gps

Segment - an area of data, usually rectanglular in shape.  Each 12345678.img file  in a mapset is a segment (quad). 

Boyd

The maps are broken up into smaller "tiles" so that the entire thing doesn't need to be loaded at once. Actually, this is an artifact left over from the time when memory was very expensive and Garmin GPS'es only had 8MB for map storage. The disk version of the 100k topo's has very small segments to maintain compatibility with older designs that had tiny amounts of memory.

Segment (tile) size is determined by the map author and can be any size or shape that they desire - there are no standards.

It used to be that Garmin sold separate data cards with regional 100k topo's. Not sure if they even offer this anymore - I believe you had to special order and they made them for you on demand. When you can get the whole US for $100, I don't think it makes sense to buy those smaller cards.

EagleBoy

I use the Ibycus maps with my Dakota 20.  Just load the ones I need (MTB and ski areas).  They overlay wonderfully onto the supplied base map  And where pray tell does one buy a 3 GB MicroSD card??  :)