I want to get the rom image from my TI-80, how can i do that since its got no link port?

Dumping the ROM of a TI-80/81 (it's the same method) is hard. It involves typing well-defined stuff at well-defined locations of the TABLE screen, so as to coerce the OS into executing code which dumps said raw OS to the screen. Then, you have to take a movie of the screen output, and perform OCR on the result.

Several members of the community have done it and would be able to tell you more than I can
EDIT: actually, I found a relevant topic again: http://tiplanet.org/forum/viewtopic.php?f=10&t=5019 . It's even more complicated than what I described above - one also has to reconstruct information that cannot be printed in the dump.

See also http://www.ticalc.org/archives/files/fileinfo/442/44236.html , but that doesn't seem to contain instructions for dumping.