I'll give it a shot:-
Machine code is basically binary. Your average 001110101 etc.. that instructs the machine what to do. If you had the time and patience you could write this...however, I think it would take a ***LONG*** time for you to do anything useful...It is the *only* language the computer understands...
Opcode is the next level up. It is the:-
MOV #F, 12
NEQ A0, D1
BNE AA, #F
That you may see around. You write this using a text editor, and get an assembler to convert this into machine code (the 0011001) for the computer to do something..It is easier to write in assembler (as it's often referred to) than in machine code
Bytecode are machine-independent implementations of a high-level language (
Java springs to mind here) that can be transferred from one machine to another. The JVM converts the byte-code into machine-code for the computer to do something...
David