Mnemonics and Operands

An assembly code instruction (statement) consists of a mnemonic (pronounced "nih-MON-ick"), and between zero and three operands. For a logical or arithmetic mnemonic with two operands, the right operand is the source and the left operand is the destination. In general, 80x86 assembly code instructions takes the following form:

[ASM|!] mnemonic destination, source

For example:

! MOV EAX, 1

ASM ADD EAX, EBX

In the examples above, the keywords MOV and ADD are the mnemonics, EAX is the destination operand, and 1 and EBX are the source operands.

In the first line, the value 1 is "moved" into the EAX operand (register). In BASIC code, this works similarly to the statement A = 1. The second example adds the value in EBX to the value in EAX and stores the result in EAX. In BASIC code, this works similarly to A = A + B.