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Favorite "iron" bug

Larry Osterman: my favorite bug is the one we found on ICL PWS-400. It was a new platform from ICL (a British company, bought by Fujitsu in 2002 ), and our task was to port MS-DOS 4.1 to this platform. The project involved five - two from Microsoft and three from ICL.
The PWS-400 hardware was quite unusual: for example, real-mode programs could switch memory banks page by page — due to this, applications could run in the background without interfering with one another.

We were five developers, we did not have testers; so we tested the new system with everything that comes handy. My favorite “testing tool” was a game that Valori ( wife ) brought with her to study. I don't remember exactly what the game was like; but every time I played it and reached a certain place, the car suddenly rebooted.

We hooked up to the ICE machine (in-circuit emulator — a device that lets us know what's going on inside and outside the processor), and found that the processor receives a reset signal from the outside. So at least the bug was not in the code.
The guys who collected the car, took the game from me, and began to understand.

A couple of days later they returned the game and told that they had found a malfunction. It turned out that the track to the dynamics passed on the motherboard too close to the restart track. When a signal of a certain type was applied to the speaker, electromagnetic radiation from the first track induced a sufficiently high voltage on the second track to be recognized by the processor as a signal to restart.

Matt Williams: I remember a couple of bugs that drove me crazy.

The first story happened in New York City. A mouse was connected to one of the computers, which randomly jumped when it only spent on a certain part of the desktop. But it did not always work. After some time, we discovered a pattern: the mouse went crazy only at a certain time of the day. And the place on the table in which she was going crazy also moved with time. We spent a lot of time before we found the cause of what is happening. But first I’ll tell you about the second bug: they are related to one another, although they have been separated for about 5 years.

By the time I moved to California and purchased a used car. Before you give it to me, the previous owners told about the strange features of the radio: spontaneously insert the disc for no reason at all. They contacted the workshop several times about this, but they could not find a fault, and the mechanics simply replaced the radio tape recorder with a new, same model. This did not help: the fault remained.
Having traveled on this car for several months, I discovered a pattern: the tape recorder spat out a disc only when I was driving in a certain direction ... and, moreover, only at a certain time of the day.

So what was the matter? Both times the sun was to blame. The mouse had a small gap between the buttons, and when the sun shone at it at a certain angle, the light penetrated inside the photo pairs and caused a reaction, as if from a ball rotating in all directions. In the same way, when the sun fell through a skylight into the charging slot of the radio, the sensor of the inserted disc worked, and the radio was spat out.

Source: https://habr.com/ru/post/102203/

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