Editing Basic Assembly Programming (section)

===== Multi-Purpose Subtraction =====

To do this, we must take advantage of the fact that computers do not care where a value came from. They only care what the value ''is''. What we want is a completely logical object, a mask that refers to ''every'' bit. But we can get it in a completely arithmetic way - the value is <code>255</code>, which in 8-bit arithmetic is the same as <code>-1</code>. What’s the easiest way to get <code>-1</code>? <code>0 - 1</code>!

We can <code>loadi</code> those values. But there’s one catch.

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