i have one question. why would you want to write a program in machine code? I mean now with such advanced programming languages from c++ to even java is there any point to learning java.

Hi you can write the Machine Code. Instead of writing mnemonics you can write opcodes in asm files , like
db 0aeh ;equal to far jmp instructions. Hope this will help u...

If you are that much of a masochist, you would have to get hold of the technical reference manual(s) for your processor, and look up how assembly language instructions are encoded into machine code.

Short of writing an operating system for a brand new model of computer, without any possibility of cross assembly, I can't imagine why anybody would want to do it.

Do universities teach that any more? I thought writing programs in machine code went out in the early 1960s, before punch cards were invented.

my dad used punchcards still at uni during the late 70's lol

There are valid reasons why someone would want to write a program in machine code, though I can't myself see why anyone would need to deal in binary. Anyhow, you can hand assemble code by swapping mneumonics with their opcodes, which are mainly giving in hex.

Only two I can think of
1) academic purposes

2) on obscure os that does not have an assembler

Patches are frequently applied in machine code. NASA's procurement process for Space Shuttle flight software had the vendor providing a "signed off" image. Subsequent fixes after image sign off were applied as machine code patches. I had 20 words of patch space to work with in the Shuttle's SP0 cockpit display processor. Split 8 here and 12 over there. A reassemply/recertification of the load image to collect them up together was too economically painful to think about. We did hex patches.

Obviously debuggers and such need to do it when they implement the ability to alter code on the fly, and OS internals often do a bit of it when applying patches to known broken apps before allowing them to execute. DOS 5 and later for example, patch the in memory image of applications built with a buggy version of the Rational Systems DOS extender before giving them control.

You proved my second reason (obscure os) -- not many people have the opportunity to program for a space shuttle.