19 juni 2006

UPDATE: Hardware Virus detection !!!

http://www.geocities.com/SiliconValley/Lakes/7156/hwvirus.htm

Hardware Virus

Electronics Australia, July 1998 pp. 36-37. The Serviceman

A hardware virus? I didn't think it was possible, until it happened to me at a most inopportune time. It all started with an external SCSI CD-ROM burner. I had been using the computer and burner for almost a year at work without problems, when one day I noticed that someone had disconnected my CD-ROM burner and JAZ drive. I reconnected the SCSI cables back to both units and that's when the problems started. I turned on the computer and found that the CD-ROM burner was not recognized by the system. I checked the connections but everything was in order. I proceeded to reboot the computer and again it had failed to see the burner.

The computer had a SCSI card in it with one hard disk connected to it internally and the external CD-ROM connected to it via the external port on the card. The external JAZ drive was connected through the CD-ROM burner also by a SCSI cable. I checked all the connections again and power-cycled the computer to find that now even the internal hard disk wasn't working. At least the SCSI drivers were not seeing it. This was odd, so I disconnected the CD-ROM burner thinking that it was faulty and causing problems on the SCSI bus. Sure enough after I disconnected the CD-ROM burner from the computer the hard disk was okay again. I breathed a sigh of relief at not having lost all my work.

Next I tried connecting only the JAZ drive to the computer. When I turned the computer back on, the hard disk still and now even the JAZ drive weren't recognized. Aha!! It was unlikely that both the burner and JAZ drive were faulty. Again I breathed a sigh of relief at not having a bad CD-ROM burner. Perhaps the SCSI controller card was faulty. I replaced it with an identical card, and again all the same symptoms of devices not being recognized occurred. That left me with one option, it must be the cable that connects the external devices with the SCSI card. This had to be it, I had replaced just about everything else. Changing the SCSI cable for a brand new cable again met with the same results. This started to become more intriguing than annoying. At this stage I was beginning to suspect the internal cable from the SCSI card to the hard disk. I replaced that only to find the same problem again. Ahhhh I had it now, the only thing remaining was the SCSI terminator right? Nope, it all checked out fine. My system only worked with no external devices connected. I tried a brand new JAZ drive by itself with the new SCSI cable I had replaced the old one with. Again the hard disk failed!!!

At that point I started to pick up the phone to call the X-files, I replaced everything I could with the same problem always showing up. I was ready to blame the poor mother board when I decided to take a close look at the SCSI-2 cable connector. I am sure that many readers are aware that the SCSI-2 connector has many small pins closely packed together. At a first glance all looked well, but then one pin caught my eye. I noticed that it was leaning too close to the one next to it. Well I was on the right track now. I straightened the pin and decided to check all the other cables, and to my surprise the identical pins on all other connectors were bent the same way, even the new cables I tried. Quickly dismissing the notion that this was "As Designed in the SCSI-2 specs.", I checked the SCSI sockets on the CD-ROM burner and JAZ drive. I noticed that the corresponding hole for the bent pin was covered by the thin piece of plastic that normally separates each of the pins on the connector.

Now it all became clear. One of the female sockets must have deformed when I first reconnected the CD-ROM burner. This forced the two pins into the same hole and shorted them out. Later when this cable was plugged into the JAZ drive, the pins, now bent to go into one hole, deformed the female connector on the JAZ drive. Again pushing the separating plastic over the hole. Plugging another good cable into this newly damaged socket caused the pins of the new cable to be forced together and short, and when this new cable was inserted into the good SCSI socket on the new JAZ drive it did more damage to it. Before I knew it I had four damaged sockets and three bad cables. The hardware virus spread like a Sydney bush fire. I am only glad the virus was contained and did not spread to the rest of the world! Can you imagine if this sort of thing happened in a big computer assembly plant?

http://www.geocities.com/SiliconValley/Lakes/7156/hwvirus.htm >