first,
there is no difference between writing in binary and asm, except one can be done about 100 times faster. it's cool that you want to learn the opcodes, but for a modern processor, it's just too much to memorize. in the end, you will end up typing in pseudo-asm and converting it to binary through a regexp script. i guess a person could learn the entire instruction set for something like PIC, because they are all short and there are less than 40 of them. but a pentium or a g3 is out of the question.
and, if you wanted to write something in binary, i suppose you could just write it in a text editor, and write a script to output it in real binary to an .obj or .exe file.
good lord that sounds tedious. or, you could save a blank file and edit it with a disk editor. that sounds like oodles of fun.
as for an opcode reference, try to find the spec sheet for the processor you are using. try here.
http://www.intel.com/design/pentium4.../index_new.htm
this will give you everything you need to know about coding binary for the p4. commands a-m take up 580 pages. and all the opcodes are in hex. sorry, you'll have to convert in your head.
