Ok, I think the exFAT formatting is the issue, and of course FAT32 can't address more than 32Gb, so Win10 won't allow me to reformat it in anything other than exFAT or NTFS. I've found an 8Gb card which can hold the new maps, so that's that bit sorted. I tried to include the OS maps I bought with the 800 years ago, but I think the UNL code may be unique to that device, and the 1000 tells me it can't unlock the map. Never mind; I don't like the OS map on the Edge anyway! Meanwhile, I've ordered a couple of 16Gb cards so I can put a decent selection of areas on both Garmins (I occasionally ride in the USA, India and South Africa).