Re: Program Interrupts (signals)
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"Just think how much easier it would have been to migrate to 32 (yes 32 bit)!"
32-bit was tried by IBM with the 360/67 and it was found there was no appetite for it in the market. If you want to see what it is all about, spin up hercules with?a BC mode PSW, with bits 4 and 5 of the PSW turned on, which indicates 32 bit addressing. There even was an OS IBM developed which supports 32 bit addressing called TSS/360.
Joe
On Sat, Apr 25, 2020 at 7:28 AM adriansutherland67 < adrian@...> wrote: What's a bit weird is the way IBM layered their hacks on hacks. And I am not trying to cause controversy because we all know what big corporations are like, and what mangers are like ... saving money but building up a technical debt. And we all know that (irritatingly) they are often right, and certainly I have buried some bodies!
In this case ... HX should have raised an interrupt which would have been manageable with one of the CMS interrupt macros. Instead weird polling.
And then?REXX came along which (like us today) needed a way for clean interrupt for the interpretation. One answer would be to fix HX, and allow the interpretor to catch the interrupt. But no - another command HI, another flag to poll!
The biggest hack was allowing the most significant byte of addresses to be used. Today, I would fire someone on the spot for doing that (or the equivalent) ... and the hardware architects should have made sure CPUs fired a machine abend if it ever found anything other than zero in that byte. Just think how much easier it would have been to migrate to 32 (yes 32 bit)!
And to get a more sympathetic hearing from this forum. In a parallel universe IBM launched their PC computer with CMS on metal not DOS. There was some impact on the mainframe business but this was completely offset by new customers and use cases. OS emulation was there from day one and later CP was introduced as the processors got more powerful. SAA was important ... etc.
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