atacontrol(8)

[Mike Maltese]

> Second, where do I have to indicate that my DVD-ROM supports UDMA66? I 
> assume that after saying "atacontrol mode 1 udma66 udma66", the settings 
> are going to be vanished the next reboot.

Add the following to /boot/loader.conf:

hw.ata.atapi_dma="1"

Reboot. Check dmesg.

> Third, why it does not want to set the DVD-ROM to UDMA66 (the device 
> supports it, as well as my 80-pin cable, and motherboard):

See above and try that first.