Hi all; Another question that is driving me nuts. It may be because I am mis-asking the question. It seems to me each peripheral (device), whether it is a hard disk, a sound card, a video card or a bus must have an identity stored on board that the BIOS or udev --probe can locate in order to set up a hwconfig table (struct). I understand that the BIOS probe and information is, or can be, different and separate from the later Linux OS probe. Once a device is recorded in the hwconfig table I can trace the actions of the kernel on modules, and drivers etc. This is a physical, hardware question: Where is the device identity registered on the device and how is it probed? Does each device have a EEPROM or is the identity hardwired in place by the manufacturer? Does a 'probe' send a signal down the control lines on a bus and report back an identity for each device it finds? How? On the Data Lines? Is there a specific function, in BIOS, in the kernel, in udev, that accomplishes this? What does the kernel do with that data? I have a kernel manual for 2.6 and greater. The manual is silent or I have mis-read something. I have gone to the various standards sites; Ieee, PCI. MAC, ISA, etc., etc. Each one of those sites register companies and release identity numbers that can be found in hwdata libraries originally obtained from (http://pciids.sourceforge.net/) None seem to say how the identity must be stored on the device or peripheral and/or how the probe is to find that identity? This started out for me as a small question. If it is too large to answer directly, is there a HowTo that answers it? I *have* checked and read the standards sites -- such as are available to me. -- Regards Bill