AHB(4)                                                     BSD Kernel Interfaces Manual                                                     AHB(4)

NAME

     ahb -- Adaptec EISA SCSI host adapter driver

SYNOPSIS

     To compile this driver into the kernel, place the following lines in your kernel configuration file:

           device scbus
           device ahb

     Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

           ahb_load="YES"

DESCRIPTION

     This driver provides access to the SCSI bus connected to an Adaptec AHA-174X host adapters in ``enhanced'' mode.  Tagged queueing and syn-
     chronous SCSI transfers are supported.

HARDWARE

     The ahb driver supports the following SCSI host adapters:

     o   Adaptec AHA-1740
     o   Adaptec AHA-1742
     o   Adaptec AHA-1740A
     o   Adaptec AHA-1742A

CAVEATS

     The Adaptec 174X is very sensitive to SCSI bus termination and cable length.  It may also have difficulties operating with some modern
     devices that, due to their speed, expose timing problems in the controller.  There are no known mechanisms for working around device incom-
     patibilities of this nature.

SEE ALSO

     aha(4), ahc(4), aic(4), cd(4), da(4), sa(4), scsi(4)

AUTHORS

     The ahb driver was written by Justin T. Gibbs.

BSD                                                                July 4, 2004                                                                BSD