I was thinking more along the lines of things that prevented earlier
operating systems from even IPLing on newer boxes. Such as z13 is the
last processor to have ESA/390 mode. I also have it in my head that at
some point there were changes to the page size and virtual storage
tables that caused havoc.
Tony Thigpen
Seymour J Metz wrote on 9/1/20 3:30 PM:
Typically the new features reqiured by a level set were added over several
generations, and each generation added more than one feature.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Tony
Thigpen <t...@vse2pdf.com>
Sent: Tuesday, September 1, 2020 3:25 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Architectural Level Sets
IBM has had several Architectural Level Set points where there were
significant changes to the CPU that prevented earlier operating systems
from running on them.
What CPU's were involved with each level, and what was the real
underlying item changed on the CPU that forced a new level? (Let's keep
it limited to z990 and newer.)
Tony Thigpen
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