On Sun, Feb 05, 2023 at 07:12:57AM +0000, Seymour J Metz wrote: > Shouldn't that be > USING ASVTBEGN,R10 ESTABLISH ADDRESSABILITY > > Or does CVTASVT point to the prefix?
It points to the prefix. This allows IBM to add fields to the ASVT without the other offsets changing. They can't add them at the end since the end has an unknown number of slots for ASCB addresses. It's possible (likely?) that the full prefix doesn't exist as allocated storage to the ASVT (ie: the unused part of the prefix overlays something else). There is a lot of code which knows the ASVT structure and possibly micro-code too... ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
