30 Oct
2015
30 Oct
'15
11:35 a.m.
On Oct 30, 2015, at 2:16 PM, Noel Chiappa <jnc at
mercury.lcs.mit.edu> wrote:
...
Apparently nobody had ever told them that a number in memory is... just a
number. At which point it became clear that they needed to know a little
more about how a computer actually worked.
That reminds me of an exchange I had with a younger colleague who was writing a document
describing how to do incremental TCP checksum update correctly. He was tripping over the
issue of negative zero. I told him the answer simply was to subtract the complement with
end around borrow. He didn't believe me and ended up proving it by exhaustively
testing every case.
Sigh.
paul