Language¶
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).