From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 101deb,3488d9e5d292649f X-Google-Attributes: gid101deb,public X-Google-Thread: 103376,e6a2e4a4c0d7d8a6 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-02-20 13:19:05 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!news.airnews.net!cabal12.airnews.net!usenet From: "John R. Strohm" Newsgroups: comp.lang.pl1,comp.lang.ada Subject: Re: status of PL/I as a viable language Date: Thu, 20 Feb 2003 15:12:13 -0600 Organization: Airnews.net! at Internet America Message-ID: <49B2A85063D94253.8DA56CE45A59733D.833C89567A587E47@lp.airnews.net> X-Orig-Message-ID: References: <6F01A9BDC686A359.6430C14E3029E8CA.6C7A1A97820C8419@lp.airnews.net> <1045770511.855483@master.nyc.kbcfp.com> Abuse-Reports-To: abuse at airmail.net to report improper postings NNTP-Proxy-Relay: library2.airnews.net NNTP-Posting-Time: Thu Feb 20 15:18:45 2003 NNTP-Posting-Host: ![N[L1k-VQjN'EK (Encoded at Airnews!) X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Xref: archiver1.google.com comp.lang.pl1:4372 comp.lang.ada:34303 Date: 2003-02-20T15:12:13-06:00 List-Id: "Hyman Rosen" wrote in message news:1045770511.855483@master.nyc.kbcfp.com... > John R. Strohm wrote: > > The Patriot system designers assumed that the system would never > > be operated for more than a few hours at a time, and the timer > > couldn't overflow in that time. > > And so is this an illustration of how Ada would have helped, > or an illustration of how Ada would not have helped? Had Ada > code raised a numeric error at the overflow, would that have > caused the missile to engage its target properly? Yes, it probably would. The uncaught exception would have taken the battery down, requiring an operator restart, a few days at the very least, before the Scud in question was launched. This in turn would have generated a frantic phone call back to Raytheon in the United States, and quite possibly generated a field patch to eliminate the problem. The workaround would be to reset the system periodically, which opens very narrow windows during which a Scud might not be engaged because the battery was rebooting, as opposed to having the battery down AND NOT KNOWING ABOUT IT. The obvious other step is to move a second battery in, and NOT reboot both of them at the same time.