Why does FreeBSD not recognize my Adaptec SCSI controller card?

The newer AIC789x series Adaptec chips are supported under the CAM SCSI framework which made its debut in 3.0. Patches against 2.2-STABLE are in ftp://ftp.FreeBSD.org/pub/FreeBSD/development/cam/. A CAM-enhanced boot floppy is available at http://people.FreeBSD.org/~abial/cam-boot/. In both cases read the README before beginning.