incompatible jmp instruction?

[nobody]

Dear list,

I have a newbie question. When I deassembled a executable file under MAC intel, I encountered following jmp instruction:
00003118  7453  je 0x0000316d
Here, the opcode 74 seems correspond to je, and 53 is a relative address. Then I tried to assemble "je 0x53" using nasm, which produced a output like:
0f  84  4f  00
which is not 74 53 any more.

So my question is where these two instructions are not the same. Thanks!

[nobody]

> So my question is where these two instructions are not the same.  

SHORT vs NEAR jump ;-)

74 53 -> je short $ + $53 , 8086 compatible

0f 84 4f 00 -> je near $ + $4F - requires 80386 , inefficient encoding !!!

You should care about your "org" and jump target ;-)

> Then I tried to assemble "je 0x53"

Bad idea to specify an absolute address :-(