* William Case <billlinux [ at ] rogers [ dot ] com> [071025 23:39]: > > BIOS is more or less customised to the Motherboard so it has in rom some > > idea of where to look for built in hardware. (keyboard etc. > > > Rhetorical question; how? Depends on the peripheral. The PS/2 keyboard is always connected on a controller that behaves the same way it did 20 years ago -- the BIOS reads and writes some IO ports to find out if the keyboard is connected. Devices connected to buses like PCI, or ISA require probing. Probing for ISA devices means you have to assume the device is there and talk to it... if it's not you get errors and timeouts. PCI is nicer and you can talk to the PCI using IO ports and later map the devices into memory-addressable space. Once you have PCI, you can probe for USB, SATA, etc. -Bart -- WebSig: http://www.jukie.net/~bart/sig/