Nikon D300 User Manual page 112

Primary Slot Selection (D300S
Only)
(User's Manual: D300S page 72)
Primary slot selection is only available in the D300S camera.
The D300 only has one memory card slot, while the D300S
has two.
This function and the next, Secondary slot function, are
concerned with where your camera stores its image files. If
you're using two memory cards, an SD and a CF, you'll need
to set these two functions to control where files go and what
happens when a card fills up.
You'll need to decide which card type you want to shoot with
most often. Will you use the SD slot as the primary or the CF
slot? If you have more of one type than the other, or simply
like one card style better, this will let you choose your
favorite.
Figure 3-8. Choosing the primary card slot
112