The language of the computer is broadly defined with the following terms:

Name Description
Assembly / Assembly code Collective name for operations in sequence to form a program. The input to the assembler.
Token A set of characters separated from other characters by spaces at the beginning and end. E.g the assembly line LOAD [#123] B has 3 tokens: LOAD [#123] and B.
Operation A specific, simple step that the computer can perform. E.g. add the value in a given register to the accumulator, or copy a value in one register to another.
Operation code / Op code A unique code used to identify an operation, e.g. AND, JUMP, or ADD.
Operation Argument A value passed to an operation to specify it’s behaviour. E.g. passing B to the ADD operation to specify that the value in register B should be added to the accumulator register.
Instruction A fully specified operation, e.g. a copy from B to C or setting the A register to a value. Effectively a line of assembly.
Instruction byte A byte that uniquely identifies an instruction.
Machine code Collective name for the bytes in program memory that form the instructions and constants of a program. The assembler generates machine code.
Machine code byte A byte that makes up machine code. Could be an instruction or an constant value.
Microcode The pattern of bits that determine the control signals to operate the computer to complete an instruction. The Control Unit contains microcode.
Microcode Step A single transfer of data via the bus or action of a module occurring on a rising clock edge. The smallest, most specific level of control. An instruction is completed by doing a number of microcode steps.

See the language table (or download it) for a complete listing of all the machine code and operations with their arguments. The table is sortable by clicking on the headers (but it’s a little slow).