Nerd Alert!

[dirtybryan]

I'm taking a computer systems course and am coming to a small stumbling block as to how negative numbers are expressed in hex in assembly language. We have a basic machine simulator they wrote in java that reads in our text assembly files and the they have created their own ISA for this machine. Our machine is big-endian is that makes any difference.

$0xFFFFFFFF should be -1 right? So would $0xEFFFFFFF be -2 and so on or am I missing something?

[Snow Dog]

It's called 2's complement and -2 is 0xFFFFFFFE using big-endian (the big end is first). To negate a number, in binary compement the number (1s become 0s and 0s become 1s) and then add 1.

[dirtybryan]

Thanks, I almost had it.