.\"	$OpenBSD: acc.4,v 1.2 1996/03/29 10:16:19 niklas Exp $
.\"	$NetBSD: acc.4,v 1.3 1996/03/03 17:13:10 thorpej Exp $
.\"
.\" Copyright (c) 1983, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\"
.\"     from: @(#)acc.4	6.4 (Berkeley) 3/27/91
.\"
.Dd March 27, 1991
.Dt ACC 4 vax
.Os BSD 4.2
.Sh NAME
.Nm acc
.Nd
.Tn ACC LH/DH IMP
interface
.Sh SYNOPSIS
.Cd pseudo-device imp "device acc0 at uba0 csr 167600 vector accrint accxint"
.Sh DESCRIPTION
The 
.Nm acc
device provides a Local Host/Distant Host
interface to an
.Tn IMP .
It is normally used when participating
in the
.Tn DARPA
Internet.  The controller itself is not accessible
to users, but instead provides the hardware support to the
.Tn IMP
interface described in
.Xr imp 4 .
The configuration entry for the
.Xr imp
must also include the
.Em pseudo-device
as shown above.
.Sh DIAGNOSTICS
.Bl -diag
.It acc%d: not alive.
The initialization routine was entered even though the device
did not autoconfigure.  This indicates a system problem.
.Pp
.It acc%d: can't initialize.
Insufficient UNIBUS resources existed to initialize the device.
This is likely to occur when the device is run on a buffered
data path on an 11/750 and other network interfaces are also
configured to use buffered data paths, or when it is configured
to use buffered data paths on an 11/730 (which has none).
.Pp
.It acc%d: imp doesn't respond, icsr=%b.
The driver attempted to initialize the device, but the
.Tn IMP
failed to respond after 500 tries.  Check the cabling.
.Pp
.It acc%d: stray xmit interrupt, csr=%b.
An interrupt occurred when no output had previously been started. 
.Pp
.It acc%d: output error, ocsr=%b, icsr=%b.
The device indicated a problem sending data on output.
.Pp
.It acc%d: input error, csr=%b.
The device indicated a problem receiving data on input.
.Pp
.It acc%d: bad length=%d.
An input operation resulted in a data transfer of less than
0 or more than 1008 bytes of
data into memory (according to the word count register).
This should never happen as the maximum size of a
.Pf host- Tn IMP
message is 1008 bytes.
.El
.Sh SEE ALSO
.Xr netintro 4
.Sh HISTORY
The
.Nm
interface appeared in
.Bx 4.2 .