Win95/98 misreports RAM

I have a pent120 running a vx board with an award BIOS.
there is 48Mb ram installed.
currently it is running win95b.
during POST the ram is reported correctly but when windows loads there is only 15Mb showing and it runs as if that is all there is too.
i had previously tried to install win98se and the problem was there as well.
any suggestions please.