athd(7)              INTERACTIVE UNIX System              athd(7)



          NAME
               athd - low-level controller module

          DESCRIPTION
               The athd module provides low-level interface routines
               between the High Performance Disk Driver (see hpdd(7)) and
               the MFM, RLL, or ESDI controllers in an AT-compatible
               machine.  It can be configured for disk support for one or
               more controller boards.  The low-level code determines if
               the controller is, in fact, present at the configured
               address (see disk(7) and tape(7)) and what devices are
               attached to it.  It handles simultaneous requests for all
               devices, overlapping operations where the devices will per-
               mit.

               For information on configuring a kernel to include the athd
               module, refer to the ``INTERACTIVE UNIX Operating System
               Maintenance Procedures.''

             Board Configuration
               The default configuration described in the User's Manual
               that accompanies the controller board should be used for
               standard configurations of the system.  If more than one
               board is to be used in a single system, each must at least
               occupy a different set of I/O address ranges and use a dif-
               ferent DMA channel.  Use of a different interrupt level for
               each board is required.

          SEE ALSO
               aha1540(7), disk(7), hpdd(7), tape(7), tmc8x0(7).
               ``INTERACTIVE UNIX Operating System Maintenance Procedures''
               in the INTERACTIVE UNIX Operating System Guide.

          ADDED VALUE
               This entry, supplied by INTERACTIVE Systems Corporation, is
               an extension of UNIX System V.



















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