Assembly Language Addition

Question

I am new to assembly language and I found this table of hex codes that I need http://www.keil.com/support/man/docs/is51/is51_opcodes.htm But my question is does it matter which "ADD" instruction I do given a certain situation since they range from 24-2F or can I just pick anyone I desire?

Answer 1

You need to choose the one that mathches what you want to accomplish, i.e., how the value you want to add is specified. Do you for instance want to add an immediate operand or a value in a register? As stated by Raymond Chen, the details are present in the fourth column.