the reset vector

[bicepjai]

you are saying the reset vector is

FFFF0000h:FFF0h

then add it as its segmented address

0xffff0000 + 0xfff0
'0xfffffff0'

according to your definition, to get linear address from segmented address, we need to multiple by 16 or left shit 4 and then add the offset right ? should it be

FFFFF000h:FFF0h

in real mode as explained in the
wiki page http://en.wikipedia.org/wiki/Reset_vector

[0xAX]

Hello @bicepjai,

all is correct. Physical address is:

0xffff0000 + 0xfff0
'0xfffffff0'

which is 4gb - 16 bytes. We no need to shift base, it's post-shifting here.

Also you can see in wiki that there is 0xfffff000 base of segment, seems that high F is just sign-expansion.