Trap representations

[Kaz Kylheku]

It's been a long time since I've heard of Scott Nudds. I wonder how he's
doing with all the traffic he must have had in his sinuses.

Scott Nudds, in 2006, on sci.environment:


``Who cares? AmeriKKKan cities are destined to be destroyed by nuclear
hellfire.

The very act of trying to prevent it will simply further ensure it's
occurrance.

Personally I will laugh on that day, as I did on 911.


So long Suckers.... ''


``> Do you rejoice when the terrorists hit their targets in the west?

911 was a Rembrant of Science and art.''


Good grief.

 

[Guest]

(e-mail address removed) writes:

Interesting.  Can you say what this machine is?  And is this at the
level of assembly, or in some other higher-level language?

ICL 1906 programmed in Algol-60.

It didn't have to handle C's unsigned chars so it didn't
need the ability to turn off the traps. I don't *know*
it was hardware (quick looks at Wiki give no hint)
but it seems expensive to do in software.

I seem to have lost my 1900 series assembler pocket
reference :-(

 

[Ben Bacarisse]

ICL 1906 programmed in Algol-60.

You say above that it was 1's complement, but my recollection is that
the 1900 series was 2's complement. That does not mean it did not
have a trap value that stood for -0 (0x800000 would be the obvious
candidate) but it makes it less likely.

 

[Richard Tobin]

You say above that it was 1's complement, but my recollection is that
the 1900 series was 2's complement. That does not mean it did not
have a trap value that stood for -0 (0x800000 would be the obvious
candidate) but it makes it less likely.

It was indeed 2s complement. I used a Fortran compiler on it which
initialised variables to the most negative integer, but as I recall
that did not act as a trap value, just as a useful indication in core
dumps.

-- Richard