On 2013-10-24, at 04:35, Rob van der Heij wrote: > Ask someone for a web browser and type google.com ;-) OS assembler > language; 360, and december 1967 > ... which seems to take me to a bitsavers page, already discussed here.
> Many moons ago, a friend (who went to math school) showed me his scars and > explained that it were evil that compilers could optimize in such a way > that an attempt to divide by zero would go unnoticed. I believe most > languages now formally specify which parts of the expression may/will not > be computed when it can be avoided. ... > Pascal, with which I am most familiar (oh, damn! OT!), makes it clear, if only by omission, that such constructs are syntactically valid but should be reported at execution. >> From: "glen herrmannsfeldt" <g...@ugcs.caltech.edu> >> Sent: Thursday, October 24, 2013 4:22 PM >> >> From C28-6514-5 on bitsavers, on page 16: >> >> "Division by zero is permitted and yields a zero result." >>> >>> After that, (and presumably also earlier) it has to stay that >>> way as code (macros) might depend on that. >>> >>> There is no reason given. >>> I don't see that it's so necessary to maintain compatibility with all historic design blunders. Consider the relatively recent detection and warnings of questionable address resolutions. Similarly a warning could be issued for division by zero, even as an error is reported for overflow. On 2013-10-24, at 06:18, robin wrote: > From: "DASDBILL2" > Sent: Thursday, October 24, 2013 10:44 PM > >> The Assembler language book does not describe how processor instructions >> work. > > Mine does. And most assembler langage books do also. >> More to the point, it describes how the Assembler (HLASM) works, and has done so since the earliest days, which is what I was wondering about. -- gil
