OS/360 always runs in BC mode. MVS 3.8J and earlier IPL in BC mode and then change the PSW to EC mode.
Joe On Wed, Sep 9, 2020 at 4:47 PM Seymour J Metz <[email protected]> wrote: > In XA mode the problem is the SIO instruction. DOS.360, OS/360, OS/VS, > etc. don't support SSCH. Does OS/360 need BC when you sysgen for S/370? I'm > certain;ly not aware of such a dependency in OS/VS or VM. > > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > > ________________________________________ > From: IBM Mainframe Discussion List <[email protected]> on behalf > of Lennie Bradshaw <[email protected]> > Sent: Wednesday, September 9, 2020 4:56 PM > To: [email protected] > Subject: Re: Architectural Level Sets > > I think this happened with the move to MVS/XA as XA does not recognise a > BC mode PSW. > So I guess it was the first machine which did not support architectures > earlier than MVS/XA. > I suspect that was the 3081. > > All my conjecture of course. Let's see what the IBM oracles tell us. > > Lennie Dymoke-Bradshaw > > -----Original Message----- > From: IBM Mainframe Discussion List <[email protected]> On Behalf > Of Mark S Waterbury > Sent: 09 September 2020 18:35 > To: [email protected] > Subject: Re: Architectural Level Sets > > To add to this thread ... > > I would like to know at what point during the evolution from S/370 to > S/370-XA to S/390 to zSeries, did the architecture stop supporting IPL of > any OS that runs in "BC mode" or that starts out in BC mode, before setting > up page and segment tables and control registers and then enabling DAT? > > In other words, what processor family(s) and specific models in that > family, if need be, can no longer IPL and run any of the "public domain" > operating systems from the 1970s to early 1980s? (DOS/360, OS/360, DOS/VS, > OS/VS1, OS/VS2, VM/370, TSS/370, etc.) > > Thanks in advance. > > Mark S. Waterbury > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send email > to [email protected] with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
