Let us stipulate that z/Architecture divide instructions, all of them, throw exceptions when a zero divisor is detected.
That said, things then get more complicated. These exceptions cannot be disabled using SPM. There is no program-mask bit available for for doing so. They can, however, be ignored more and less systematically. Prototypically, I can write ON ZERODIVIDE ; in PL/I. This null on unit ensures that zero divides will be ignored within its scope. Moreover, there is now a functionally equivalent, albeit less perspicuous, facility available via the LE in all IBM statement-level languages that use it, i.e., for all of the usual suspects and even for LE-compatible assembly language. Paul Gilmartin and I do not always agree, but he knows all about zero-divide exceptions. What he was asserting was not that these exceptions do not occur but there are environments in which they are ignored. John Gilmore, Ashland, MA 01721 - USA
