>> PC has a larger address space, but IBM still has to reserve numbers for its >> own use, and 3rd party vendors still must avoid collisions.
Avoid collisions? PC number is formed by ETE sequence number suffixed to LX number returned by LXRES. As someone who has written quite a few software products that provide PC routines, I have never had to worry about collisions with IBM (or other ISV) software. -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Seymour J Metz Sent: Wednesday, August 28, 2019 6:35 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Assembler :- PC Instruction PC has a larger address space, but IBM still has to reserve numbers for its own use, and 3rd party vendors still must avoid collisions. -- Shmuel (Seymour J.) Metz https://nam01.safelinks.protection.outlook.com/?url=http:%2F%2Fmason.gmu.edu%2F~smetz3&data=02%7C01%7C%7Cdc0dd6d386f14dd64c6708d72bde10d2%7C79544c1eed224879a082b67a9a672aae%7C0%7C0%7C637026105076814212&sdata=g0T%2FxZM94KxBQ0MVmkG%2B1WyyUxqsn6v4qL8W6cuyMfU%3D&reserved=0 ________________________________________ From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Charles Mills <charl...@mcn.org> Sent: Wednesday, August 28, 2019 1:09 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Assembler :- PC Instruction Correct me if I am wrong. I don't pretend to be an expert on this subject. I think of SVCs as hailing from the era of centralized monolithic operating system construction. I would guess that IBM had an "SVC number committee" and they sat down and said "SVC 1 shall do this; SVC 2 shall do that; and so forth." Yes, you can add a user SVC, but fundamentally the SVC has a fixed architecture of 256 possibilities, requiring some sort of central administration. Chris and I cannot both add an SVC 201 to our customers' computers. (Yes, having the number in a config file would be a workaround.) PCs are inherently much more decentralized. There can be a nearly unlimited number of PCs. Chris and I can both add a PC to our customers' computers without much fear of a collision. And yes, not to disagree with what Chris says, the architecture of SVC is more suited to a single address space, or at least an addressing scheme in which all "privileged services" are at least partially resident in common address space. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Christopher Y. Blaicher Sent: Wednesday, August 28, 2019 9:48 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Assembler :- PC Instruction Never measured SVC vs PC. While in some cases PC and SVC are similar, in many ways PC is far superior to SVC. It can be local or globally defined and it can be dynamically defined and removed. (OK, so can an SVC be added and deleted, but I think PC's are easier). Also, an SVC can't do space switching. ---------------------------------------------------------------------- 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 ================================ Rocket Software, Inc. and subsidiaries ■ 77 Fourth Avenue, Waltham MA 02451 ■ Main Office Toll Free Number: +1 855.577.4323 Contact Customer Support: https://my.rocketsoftware.com/RocketCommunity/RCEmailSupport Unsubscribe from Marketing Messages/Manage Your Subscription Preferences - http://www.rocketsoftware.com/manage-your-email-preferences Privacy Policy - http://www.rocketsoftware.com/company/legal/privacy-policy ================================ This communication and any attachments may contain confidential information of Rocket Software, Inc. All unauthorized use, disclosure or distribution is prohibited. If you are not the intended recipient, please notify Rocket Software immediately and destroy all copies of this communication. Thank you. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
