From: Larry__Weiss Newsgroups: alt.folklore.computers Subject: debugging Date: Sat, 28 Jun 2003 09:32:50 -0500 Organization: Airnews.net! at Internet America Lines: 22 Message-ID: <3EFDA712.DB954F6D@airmail.net> References: <3ef8f61a.8785541@news.ocis.net> <3efa509c$1@news.ucsc.edu> <0hohdb.qvp.ln@teabag.cbhnet> Abuse-Reports-To: abuse at airmail.net to report improper postings NNTP-Proxy-Relay: library1-aux.airnews.net NNTP-Posting-Time: Sat, 28 Jun 2003 09:32:45 -0500 (CDT) NNTP-Posting-Host: !`rSO1k-WM`pej77O-F` (Encoded at Airnews!) Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.imp.ch!news.imp.ch!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!news.airnews.net!cabal12.airnews.net!usenet Xref: chonsp.franklin.ch alt.folklore.computers:142792 jmfbahciv@aol.com wrote: > cbh@ieya.co.REMOVE_THIS.uk (Chris Hedley) wrote: > > The only time that something > > that's fundamentally broken actually decides to work is when I would > > really, really rather it didn't. > > That's why debugging is an art. > I just love to hear accounts of interesting debugging stories. Seems we've all had occasions where adding instrumentation to a program makes the bugs hide like roaches when the lights are turned on. I also have had to fix two bugs simultaneously because the two had a strange symbiotic relationship where keeping both bugs in resulted in only minor misbehavior (like leaving too much unused space on a page in a report) but fixing only one but not the other abended the report generator. I always intended to keep a detailed journal of such interesting bugs, but I have neglected to do so. ###### Newsgroups: alt.folklore.computers Subject: Re: debugging References: <3ef8f61a.8785541@news.ocis.net> <3efa509c$1@news.ucsc.edu> <0hohdb.qvp.ln@teabag.cbhnet> <3EFDA712.DB954F6D@airmail.net> From: Paul Pluzhnikov Message-ID: X-Newsreader: Gnus v5.7/Emacs 20.7 Lines: 17 Date: Sat, 28 Jun 2003 15:05:16 GMT NNTP-Posting-Host: 66.215.89.149 X-Complaints-To: abuse@earthlink.net X-Trace: newsread2.prod.itd.earthlink.net 1056812716 66.215.89.149 (Sat, 28 Jun 2003 08:05:16 PDT) NNTP-Posting-Date: Sat, 28 Jun 2003 08:05:16 PDT Organization: EarthLink Inc. -- http://www.EarthLink.net Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.imp.ch!news.imp.ch!snoopy.risq.qc.ca!newsfeed.news2me.com!elnk-pas-nf2!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!newsread2.prod.itd.earthlink.net.POSTED!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:142815 Larry__Weiss writes: > I just love to hear accounts of interesting debugging stories. You will enjoy reading this (IMHO excellent) book then: Debugging: The Nine Indispensable Rules for Finding Even the Most Elusive Software and Hardware Problems by David J. Agans http://www.amazon.com/exec/obidos/tg/detail/-/0814471684 It has quite a few "war stories". Cheers, -- In order to understand recursion you must first understand recursion. ###### From: "Nico de Jong" Newsgroups: alt.folklore.computers References: <3ef8f61a.8785541@news.ocis.net> <3efa509c$1@news.ucsc.edu> <0hohdb.qvp.ln@teabag.cbhnet> <3EFDA712.DB954F6D@airmail.net> Subject: Re: debugging Lines: 37 MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Message-ID: Date: Sat, 28 Jun 2003 17:46:11 +0200 NNTP-Posting-Host: 129.142.193.202 X-Complaints-To: abuse@get2.net X-Trace: news.get2net.dk 1056815512 129.142.193.202 (Sat, 28 Jun 2003 17:51:52 CEST) NNTP-Posting-Date: Sat, 28 Jun 2003 17:51:52 CEST Organization: get2net Internet Kunde Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.imp.ch!news.imp.ch!uni-erlangen.de!news-nue1.dfn.de!news-lei1.dfn.de!newsfeed00.sul.t-online.de!t-online.de!skynet.be!skynet.be!newsfeed1.uni2.dk!news.get2net.dk.POSTED!53ab2750!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:142796 > > > I just love to hear accounts of interesting debugging stories. > Well, here is one of the worst ones, I hope. Back in the early 80s, I was employed by Philips (not Phillips, the oil company, but Philips, the radio and TV maker). Philips had its own minicomputerseries, the PTS 6000. Used for things like front office, minibank systems, and others. My responsibility was a financial system for counties, so suppliers could get paid, social cases could get their money, etc. It also had batch transmission to a central countyowned site (Kommunedata, for those familiar with Denmark). What happened now, was that Kommunedata said that a correction in one transaction type was to be implemented. So, starting programming, testing, sending out new programs etc. The county was a bit slow, so after a week or so, the called me and said that they didnt want the new version, as is had some side effects they didnt want, and they didnt use that specific transaction in the first place. No harm done, so we went to look for the harddisk (5.0 MB !) with the old version. Now the shit hit the fan, as the disk had been used for something else, and there was no backup. The only thing to do, was therefore to look in the object code, locate the things to be changed, edit them in hex, and pad unused portions with NO-OPs. This was of course a bit time consuming, and we had an angry customer on the blower about three times a day. We therefore at long last said, that we would ship out a version later on the day (it was thursday), so he could be running again friday. We werent half finished thursday evening, so we sent him a defective 8" floppy disk on purpose. He called of course fridaymorning and we said that we were really sorry, and that we would ship him a new disk at once. Luckily he did not insist on picking it up himself. Sunday afternoon, just before the postbox was emptied for the last time, we tossed the disk in the box and went home. He was happy again. Nico ###### From: Larry__Weiss Newsgroups: alt.folklore.computers Subject: Re: debugging Date: Sat, 28 Jun 2003 11:35:06 -0500 Organization: Airnews.net! at Internet America Lines: 22 Message-ID: <3EFDC3BA.417B5B78@airmail.net> References: <3ef8f61a.8785541@news.ocis.net> <3efa509c$1@news.ucsc.edu> <0hohdb.qvp.ln@teabag.cbhnet> <3EFDA712.DB954F6D@airmail.net> Abuse-Reports-To: abuse at airmail.net to report improper postings NNTP-Proxy-Relay: library1-aux.airnews.net NNTP-Posting-Time: Sat, 28 Jun 2003 11:35:06 -0500 (CDT) NNTP-Posting-Host: !an2;1k-W2nWgd5,?M8Q (Encoded at Airnews!) Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.imp.ch!news.imp.ch!206.252.192.28.MISMATCH!news.stealth.net news.stealth.net!news.stealth.net!cyclone1.gnilink.net!news.airnews.net!cabal12.airnews.net!usenet Xref: chonsp.franklin.ch alt.folklore.computers:142791 Nico de Jong wrote: > ... we went to look for the harddisk (5.0 MB !) with the old > version. Now the shit hit the fan, as the disk had been used for something > else, and there was no backup. > The only thing to do, was therefore to look in the object code, locate the > things to be changed, edit them in hex, and pad unused portions with NO-OPs. > Glad that it turned out alright! I remember clearly when (coding in assembly) we quite intentionally added in unused areas of allocated memory in a program just in case we needed to add "patch code" later by doing a patch (at the customer's site) to the program's loadable image. Keeping track of the fix revisions and the collection of these patches was real work! I had one supervisor that added a program to a product that he was very proud to have written strictly as a sequence of bytes (no source code ever existed, intentionally). He didn't understand why I thought that may not have been the most clever way (especially in the long run) to introduce production components to a product. I guess he was definitely a vintage-era "Real Programmer". ###### Message-ID: <3EFDD2DB.DEAB29F7@yahoo.com> From: CBFalconer Reply-To: cbfalconer@worldnet.att.net Organization: Ched Research X-Mailer: Mozilla 4.75 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: alt.folklore.computers Subject: Re: debugging References: <3ef8f61a.8785541@news.ocis.net> <3efa509c$1@news.ucsc.edu> <0hohdb.qvp.ln@teabag.cbhnet> <3EFDA712.DB954F6D@airmail.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 30 Date: Sat, 28 Jun 2003 18:05:40 GMT NNTP-Posting-Host: 12.90.169.216 X-Complaints-To: abuse@worldnet.att.net X-Trace: bgtnsc04-news.ops.worldnet.att.net 1056823540 12.90.169.216 (Sat, 28 Jun 2003 18:05:40 GMT) NNTP-Posting-Date: Sat, 28 Jun 2003 18:05:40 GMT Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!irazu.switch.ch!switch.ch!news.maxwell.syr.edu!wn14feed!worldnet.att.net!bgtnsc04-news.ops.worldnet.att.net.POSTED!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:142789 Larry__Weiss wrote: > ... snip ... > > I just love to hear accounts of interesting debugging stories. My worst one was long ago, in the days of Teletypes and discrete logic (no namby-pamby ICs involved, they hadn't even been invented). Since TTYs tend to self destruct when left running, we included a motor control unit which switched it on on demand. The unit had all the necessary noise suppression networks across contacts, etc. However we found that the equipment would fail regularly at times seemingly unconnected with motor turn-on, within a time span of seconds. After many hours of peering into scope hoods at single traces (no digital storage scopes in those days) it was traced to a noise pulse. However the TTY was running smoothly by then. I finally realized that the noise was caused by the motor start-up internal circuitry, which depended on an internal centrifugal switch controlling other windings. Once the cause was detected, a suppression network ended the problem forever. -- Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net) Available for consulting/temporary embedded and systems. USE worldnet address!