Gil,

That's the whole point of Assembler - you can do anything, and it's up to you to ensure that what you do makes sense!

If you require more "hand-holding" from your tools, you need to move to something like 'C' - which, by restricting some of what you can do, is able to warn you of more possibly-incorrect coding!

But, as we know, even a 'C' compiler can't spot all the mistakes in our code! ;-)

I don't know if there's any equivalent of something like lint for any Assembler, let alone 8051 Assembler?