Thanks, Mark. Nice place for them to put product specifications. So, 8GB in size, but no indication of file systems nor cluster sizes.
According to this
https://support.microsoft.com/en-us/kb/140365 page, MS Windows default cluster sizes are as follows:
FAT16, 256MB - 512MB: 8K clusters (Assuming that overlapping ranges include the upper value and not the lower one. What is it with documentation these days?)
FAT16, 512MB - 1GB: 16k clusters
FAT16, 1GB - 2GB: 32K clusters
FAT32, 256MB - 8GB: 4K clusters
Since my 512MB FAT16 worked, Rigol claims 8GB works, and my 2GB FAT16 doesn't, I guess the scope can handle up to 8K clusters, maybe 16K (untested), but not 32K.
Note: Mine were formatted by default with FAT16, not FAT32.
Anyone have a 1GB drive formatted with FAT16?