Bit 32 is used for addressing in AMODE 64; it is only in AMODE 31 and AMODE 24 that it is ignored. In AMODE24 and AMODE31 it is normally referred to as bit 0 of the right half of the register, although it is legal to use grande instructions in those modes.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Steve Smith <sasd...@gmail.com> Sent: Tuesday, February 19, 2019 2:47 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Any easier way to determine if DD is dummy than GETDSAB? Bit 32 is pervasively used as a flag, most typically the end of a list. As far as the hardware goes, it is ignored for addressing. I'm not going to bother looking up the DEVTYPE specifications, but I believe it has a variable-length parm list. So it would have reason to care. sas On Tue, Feb 19, 2019 at 2:23 PM Charles Mills <charl...@mcn.org> wrote: > Thanks all. > > DEVTYPE did the trick. Catches both omitted and DUMMY/NULLFILE with > minimum extraneous fuss. > > DEVTYPE is dead simple, and also dead simple-minded. Did not like a high > order X'80' in the second address, and I am too simple-minded to get an > NILH right in less than about five tries. > > Brings to mind an interesting question. The AMODE is 31, right, not 32? > Should a service not ignore bit 32? It ignores bits 0-31, which are > irrelevant to AMODE 31, so why not bit 32?. > > Charles > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On > Behalf Of Steve Smith > Sent: Tuesday, February 19, 2019 8:51 AM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Any easier way to determine if DD is dummy than GETDSAB? > > If the customer has to specify any JCL, then using a specified DDname is > the idiomatic way to go. > > DEVTYPE is dead simple for sniffing out DUMMY vs. spool vs. DASD vs. TAPE > vs. missing. I wouldn't use RDJFCB just for that. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > -- sas ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
