Debugging: The 9 Indispensable Rules for Finding Even the Most Elusive Software and Hardware Problems
Format: PDF / Kindle (mobi) / ePub
The rules of battle for tracking down -- and eliminating -- hardware and software bugs. When the pressure is on to root out an elusive software or hardware glitch, what's needed is a cool head courtesy of a set of rules guaranteed to work on any system, in any circumstance. Written in a frank but engaging style, Debugging provides simple, foolproof principles guaranteed to help find any bug quickly. This book makes those shelves of application-specific debugging books (on C++, Perl, Java, etc.) obsolete. It changes the way readers think about debugging, making those pesky problems suddenly much easier to find and fix. Illustrating the rules with real-life bug-detection war stories, the book shows readers how to: * Understand the system: how perceiving the ""roadmap"" can hasten your journey * Quit thinking and look: when hands-on investigation can't be avoided * Isolate critical factors: why changing one element at a time can be an essential tool * Keep an audit trail: how keeping a record of the debugging process can win the day"
forgotten about my automatic TV game paddle when , months later, we were proudly showing off our prototype to the entrepreneur who was funding the project. (Yes, he was the investor, and, amazingly enough, it didn 't fail.) He liked the way it played, but he wasn't happy . He complained that there was no way to turn on two practice walls . (He'd seen an early prototype where unplugging both paddle controllers resulted in two practice walls, with the ball Now, you might be absolutely positi/Je
the system into software and hardware, and because he knew that the problem had been getting worse over time, he guessed that the problem was hardware. Then he looked at hardware signals halfway along the path; seeing bad signals confirmed his hardware guess. He continued to look at signals, and each time he saw badness on one side, he moved his search halfway along the path in the direction of the badness. When he went past the badness (it was now on the computer side). his next look was halfway
the control box and find several possible tributaries: the main power, the thermostat, and the fire safety overrid e. You cou ld go to the breaker panel to check the main power, but a meter at the control box tells you there's power, so you ignore that tributary. You could go take apart the thermostat, but a meter at the control box tells you it's calling for heat properly, so yo u ign ore that tributary. You could go look at the fire safety breaker, and yo u do, because a meter at the control
USED BY MISTAKE) .J t 8 BITS! (ONLY 7 GUARANTEED, BUT ALL 8 SENT BY EMULATOR) tas~ hmim lor I~e Kea~er 148 the bug was there, waiting to be discovered. If the ISDN system had been used in a real restricted phone company circuit, it would have failed iust like the V.35 system." The rules, used and (neglected): 149 6. Understand the System. Not only was I familiar with both the hardware and the software, but I had no reason to point the finger at anyone else. (Finger-pointing when there's
obviously important a nd tha t you would never guess. An earlier chapter dis cussed someone who stuck floppy disks to a file cabinet with a magnet. There's anoth er famous story about a guy who co pi ed data onto a floppy , stuck on a blank label, and then rolled it through a typewriter to type th e label. You would never do this. As a resu lt, you would never think to ask if th e use rs did this. All you can do is ask ne View Irom I~e nelp ~es~ 167 what happened, and then what happened, and