Never has been allowed. From the POPS for all integer divide instructions:
When the divisor is zero, or when the magnitudes of the dividend and divisor are such that the quotient cannot be expressed by a 32-bit signed binary integer, a fixed-point-divide exception is recognized. This includes the case of division of zero by zero. For HFP divide it says: When the divisor fraction is zero, an HFP-divide exception is recognized. This includes the case of division of zero by zero. For BFP and DFP divide it says: If the divisor is zero but the dividend is a finite number, an IEEE-division-by-zero exception is recognized. If the dividend and divisor are both zero, or if both are infinity, regardless of sign, an IEEE-invalid operation exception is recognized. Chris Blaicher Principal Software Engineer, Software Development Syncsort Incorporated 50 Tice Boulevard, Woodcliff Lake, NJ 07677 P: 201-930-8260 | M: 512-627-3803 E: [email protected] -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of Paul Gilmartin Sent: Wednesday, October 23, 2013 7:31 PM To: MVS List Server 2 Subject: Why is division by zero permitted? On 2013-10-23 17:54, Kurt LeBesco wrote: > I've been reading quietly and wondering how the dialog drifted off to > rexx and pl1 land. Can we get back on topic? Thanks > OK. Pure HLASM. I've long wondered why division by zero is permitted in arithmetic expressions when otherwise overflows (even in division) are reported as errors. The only rationale I can think of (and a poor one) is that it was initially an implementation oversight that was so rapidly codified by use that when it was discovered no repair was feasible. -- gil
