On Sat, 2022-10-29 at 23:52 -0500, Doug Harvey wrote:
I don't know how many instructions there are, or when new
instructions were added, but it would be pretty cool if (say)
Hercules could be started to run with the 01-May-1980 CPU instruction
set, 01-July-1990 CPU instruction set, etc.
Hercules was never designed to operate that way. As the architectures
expanded over the years, Hercules maintains the current level of the
architecture. For S/370 that means Hercules emulates the LAST
Principles of Operation manual for S/370.
As Fish said, Never!
Admittedly there are some challenges with the latest architecture, but
we are well past those considerations for S/370.
Harold Grovesteen
doug
On Oct 29, 2022, at 11:28 PM, Fish Fish <david.b.trout@...>
wrote:
Joe Monk wrote:
Tony Harminc wrote:
[...]
I really don't see that it's a bug. Maybe a less than ideal
implementation, but who's to judge that?
Well, when it was implemented it was the only way!
MODULE NAME = IEAVEVAL
CSECT NAME = IEAVEVAL
DESCRIPTIVE NAME = VALIDITY CHECK
COPYRIGHT = N/A
STATUS = VS2-RELEASE2
As we can see, it was implemented in OS/VS2 release 2. Long
before MVS 3.8J and the TPROT instruction...
Yes, I can see that, and I can certainly understand it as well. As
you say Joe, at the time, it was the *only* way it could be done,
and thus cannot *technically* be classified (considered) as a bug.
I agree 100% with that.
But I personally think it's quite telling that IBM did eventually
"fix" (change) that particular routine to properly use the 'TPROT'
instruction instead in their later versions of MVS up to and
including the latest version of z/OS (which doesn't exhibit the
problem).
If using 'CS' instead of 'TPROT' isn't (wasn't / shouldn't be
considered) a bug, then why did they feel the need to "fix"
(change) it in later versions? Why didn't they simply leave well
enough alone? After all, if it ain't broke, don't fix it! Right?
If the version of MVS that's being used (3.8j) was only being run
on the same/similar hardware that it originally ran on where the
'TPROT' instruction wasn't available, then it makes sense leaving
it alone, as-is. But it's not. It's being run on "newer hardware"
(Hercules) where the 'TPROT' instruction *is* available, thereby
rendering what WAS "the proper/only way to do it" into "the
improper way to do it for the hardware we're ALWAYS going to be
running on".
I still say it's something that should be fixed.
I'll gladly retract my "bug" claim, but I'm NOT going to change my
stance regarding it being something that SHOULD (IMHO) be fixed
(changed).
--
"Fish" (David B. Trout)
Software Development Laboratories
mail: fish@...
