Question How does a PC know what a connected device is?

[pccobbler]

When I connect a CD-ROM drive to a PC, Device Manager (for Windows) knows what type of hardware it is. How is that done? Is there a textfield with "CD-ROM" in it in the device? Or is it a numeric field, for example, "12345" which translates to CD-ROM? If someone wants to point me to a technical webpage that explains this, wonderful.

 

[rgd1101]

device id

 

[fzabkar]

The CD is an ATAPI device. It returns ID info in response to an IDENTIFY PACKET DEVICE command.

https://people.freebsd.org/~imp/asiabsdcon2015/works/d2161r5-ATAATAPI_Command_Set_-_3.pdf (page 163)

 

[punkncat]

One of the aspects I have really appreciated since W7 was for the update system to know what drivers to get. Before that you had to manually look up the Hardware ID and find suitable drivers (if you lost your drivers disk).