Negative arithmetic

Dlwigwam

I know that negative numbers cut the range of a variable, but is there a special way to do arithmetic? The following gives me an overflow value, rather than -30:

DEBUG DEC 20-50

Electrodude

It gave you 65506, right? Try this:

DEBUG SDEC 20-50     'should print 30

The SDEC tells the DEBUG command that your number is signed (-32768 - +32767) as opposed to unsigned (0-65535). 65506=65536-30

Dlwigwam

Thanks! So the value is stored as negative, and we just need to let DEBUG know that?

SRLM

It all depends on how you interpret the number. The S in SDEC tells DEBUG to interpret the number as 2's complement.