As you have an old laptop, it may not be able to use SDHC cards, it may only be able to see SD cards, which I think only went upto 2Gb.
However, if you are still interested in trying to mount an SD(HC) card, it would likely be :-
mount -t msdos /dev/da0s1 /mnt
Some systems use da0s1 others da0p1, so try both, (also da1).
You may find the info you need through 'dmesg'.
Linux user between 1999 - 2014; now a BSD user.