Translating nasm boot strap to as

I got some little code in intel syntax(nasm) and want to translate it to 
AT&T syntax to assembly it with as.

The code is a bootstrap and can be found here: http://ideone.com/Qldvx


I got problem to translate 2 things ..
this:

jmp 07C0h:start


I try this

jmp 0x7C0, start

but got "Too memory operands error"
I also try all order combinations plus $ prefix combinations

and to fill the file:

times510-($-$$)  db  0

I didn't find any $$ translation in as


-- 
"Do or do not... there is no try" Yoda Master