.\"	$OpenBSD: ahsc.4,v 1.9 2001/10/05 14:45:53 mpech Exp $
.\"
.\" Copyright (c) 1994 Christian E. Hopps
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.Dd August 31, 1994
.Dt AHSC 4 amiga
.Os
.Sh NAME
.Nm ahsc
.Nd A3000 low level SCSI interface
.Sh SYNOPSIS
.Cd "ahsc0 at mainbus0"
.Sh DESCRIPTION
The
.Tn Amiga
architecture uses a common machine independent scsi sub-system
provided in the kernel source.
The machine independent drivers that use this code access the hardware
through a common interface.
(see
.Xr scsibus 4 )
This common interface interacts with a machine dependent interface,
such as
.Nm ahsc ,
which then handles the hardware specific issues.
.Pp
The
.Nm
interface handles things such as DMA and interrupts as well as
actually sending commands, negotiating synchronous or asynchronous
transfers and handling disconnect/reconnect of SCSI targets.
The hardware that
.Nm
uses is based on the WD33c93 SCSI chip.
.Sh DIAGNOSTICS
.Bl -diag
.It sbicwait TIMEO @%d with asr=x%x csr=x%x
The 33c93 code (sbic) has been waiting too long for a SCSI chip
operation to complete.
%d is the line in the source file
.Pa amiga/dev/sbic.c
at which the SCSI chip timed-out.
Asr and csr are status registers withing the SCSI chip.
.It ahsc%d: abort %s: csr = 0x%02x, asr = 0x%02x
A SCSI operation %s was aborted due to an error.
.It ahsc%d: csr == 0x%02i
An error has occurred within the SCSI chip code.
.It ahsc%d: unexpected phase %d in icmd from %d
The target described by
.Sq from %d
has taken the SCSI bus into a phase which is not
expected durring polled IO.
.It ahsc%d: unexpected phase %d in icmd from %d
The target described by
.Sq from %d
has taken the SCSI bus into a phase which is not
expected during DMA IO setup.
.El
.Sh SEE ALSO
.Xr scsibus 4
.Sh HISTORY
The
.Nm
interface first appeared in
.Nx 0.9a