Actually, the 770 indeed has only one MMC slot (a half-height at that).
The rest is flash memory, not an internal card. I don't remember
how IT OS 2005 saw it (I flashed my 770 with 2006 as soon as it was out,
and it now has 2007); I think it was /media/mmc.
Of course, OS 2006+ had support for /media/mmc1&2, since it was written
with the n800 in mind.
N.