I recently found the site and appreciate all the work folks have in putting this together. There's some great stuff here.
I've had a 60cs for a while, and have been using the Mapsource 3 cd set and a PC and to load maps onto it.
I recently got an Astro 220 and ran the conversion at the Garmin site so that I could use the Mapsource CDs on the Mac. I put the converted maps on a flash drive and loaded them onto the Mac, and was able to load them onto the Astro, which uses a micro SD card.
I put the Astro into Mass Storage Mode and was able to get most of the East maps onto the card--I guess you're limited to 2025 segments.
I downloaded the SE Topo from John M here, which is much more detailed than the Garmin maps. I have not been able to load it onto the card. The card I have is not a Garmin card, but I did load the Garmin east maps onto it. When I try to download John M's SE Topo maps, it goes through the routine (which takes a while), and when it is done the SE map is not there, but the Garmin maps I loaded still are. This was a new card when I put the Garmin maps on it.
I thought that the new maps would overwrite the ones that were on there, but it is not.
I did with the Astro in Mass Storage Mode and then tried it directly onto a card reader and got the same results. It's a 4 gig card which is plenty big enough, and there are only 400 something segments on the map.
I used Basecamp and Mapinstall to load the maps.
I went through the tutorial here and looked through the forum, and can't figure out what I'm doing wrong. I did the same procedure when I loaded the converted Garmin maps and it worked fine, but when I do it with the SE Topo map it does not work.
Any help is greatly appreciated!