Assembly language resembles machine language (machine code).

Originaly programmers wrote code in machine language. Since machine language is hard to write code in assembly language was invented.

However assembly language is a mnemonic form  (-> AssemblyMnemonic )  of writing machine language.


A cpu executes instructions one at a time. An instruction is composed of an operator and an operand. In machine language both operator and operand are expressed in numerical values.

Imagine the machine encoded instruction:

01000010

resembling the operation 0100 on the operand 0010. Here the operation 0100
has the task to clear a memory-address 0010, or possibly a register (which is a spicific type of address).

So for the operation part 0100 of the instruction we could substitute 0100 with the mnemonic CLR, clear. In case the latter part 0010 would resemble a register, for instance the accumulator, we could invent the mnemonic A , meaning the A-register.

This would lead to the assembly instruction:

CLR     A

Else, in case of the operand 0010 being a memory-address, 0010 could be replaced with a sybol of our own making for instance MEM1.

This would lead to:

CLR     MEM1

Now this is far better to write code in.