.TH APM 3
.SH NAME
apm \- Advanced Power Management 1.2 BIOS interface
.SH SYNOPSIS
.nf
.B bind -a #P /dev

.B /dev/apm
.SH DESCRIPTION
.PP
This device presents a low-level interface to
the APM 1.2 bios calls.
It is enabled by adding the line
.RB `` apm0= ''
to 
.IR plan9.ini .
(The value after the equals sign is ignored; the presence of
the line at all enables the driver.)
It is only available on uniprocessor PCs.
Writing a 386
.B Ureg
structure and then reading it back executes an APM call:
the written registers are passed to the call,
and the read registers are those returned by the call.
.\" .PP
.\" In addition, the following strings may be
.\" written to
.\" .B /dev/apm
.\" to negotiate with other kernel devices about
.\" suspension of the system.
.\" .TP
.\" .B "vote suspend
.\" Poll kernel devices for objections to suspending the system.
.\" The write succeeds only when no device objected.
.\" .TP
.\" .B "abort suspend
.\" Notify kernel devices that the vote failed and the
.\" suspension will not happen.
.\" .TP
.\" .B "commit suspend
.\" Notify kernel devices that the vote succeeded and
.\" suspension will happen.  The devices
.\" may take measures such as disabling PCMCIA cards.
.\" .TP
.\" .B "resume suspend
.\" Notify kernel devices that the system has come back
.\" after a suspension.
.\" The devices may take measures such as reenabling PCMCIA cards.
.\" .PD
.\" A similar set of messages governs entrance into
.\" .B standby
.\" mode.
.PP
This device is intended to enable more user-friendly
interfaces such as 
.IR apm (8).
.SH SOURCE
.B /sys/src/9/pc/apm.c
.br
.B /sys/src/9/pc/apmjump.s