77 lines
3.2 KiB
Groff
77 lines
3.2 KiB
Groff
.\"
|
|
.\" Copyright (c) 1993 Christopher G. Demetriou
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by Christopher G. Demetriou.
|
|
.\" 3. The name of the author may not be used to endorse or promote products
|
|
.\" derived from this software without specific prior written permission
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.\" $Id: npx.4,v 1.4 1995/02/17 09:43:46 jtc Exp $
|
|
.\"
|
|
.Dd August 6, 1993
|
|
.Dt NPX 4 i386
|
|
.Os NetBSD 0.8a
|
|
.Sh NAME
|
|
.Nm npx
|
|
.Nd
|
|
Numeric Processing Extension coprocessor and emulator
|
|
.Sh SYNOPSIS
|
|
.Cd "options MATH_EMULATE"
|
|
.\" XXX this is awful hackery to get it to work right... -- cgd
|
|
.Cd "npx0 at isa? port" \&"IO_NPX0\&" irq 13
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm npx
|
|
driver enables the use of the system's Numeric Processing Extension
|
|
coprocessor,
|
|
if one is present. Numeric processing extensions are present in
|
|
systems with
|
|
.Nm 486DX
|
|
CPUs and in systems with
|
|
.Nm 387
|
|
or
|
|
.Nm 487SX
|
|
coprocessors. The
|
|
.Nm npx
|
|
driver is required for proper system functioning regardless
|
|
of whether or not a NPX is present.
|
|
.Pp
|
|
If there is no NPX present in the system, the "MATH_EMULATE"
|
|
option must be defined in the kernel configuration file.
|
|
It will provide support for the instructions normally executed
|
|
by the NPX. If there is no NPX in the system and the kernel
|
|
is not built with math emulation, the system will not boot.
|
|
.Sh CAVEATS
|
|
The emulator is much slower than the NPX coprocessor.
|
|
This will result in poor floating-point math performance
|
|
if the emulator must be used.
|
|
.Sh BUGS
|
|
There are lots of them, especially on cheap motherboards. In particular,
|
|
some motherboards do not have the interrupt lines from the NPX to
|
|
the CPU wired properly. If this is the case, the emulator must be used
|
|
if consistent system operation is desired.
|
|
.Pp
|
|
Emulation of the transcendental functions instructions is incorrect.
|
|
Emulation of other instructions is suspect.
|