2.2.2 Switching the PX-8
on
and
off
The PX-S has a power switch
on
the right hand side (see fig 2.3) which
is
the
normal way the computer
is
switched
on
and
off
at
the beginning and end
of
a session
of
using the PX-S. However, the PX-S
is
not switched
off
completely
as a mains operated computer would be
if
the power was turned off. The pow-
er switch can be thought
of
as a means
of
temporarily halting the operation
of
the computer, so that the batteries are conserved. As soon as the power
is
turned
on
again it
is
possible
to
begin exactly where you left off, even
if
you
were in the middle
of
typing a word
or
running a program.
The power switch
is
not the only means by which the power can be switched
on
and off. The power switch
of
the PX-S
is
controlled by the computer, and
can and
is
switched
off
under software control. Thus,
if
it
is
not used for a
length
of
time (which can be set by the user using the CONFIG program
described in Chapter 3), it will switch itself
off
to
conserve power. The user
can also program the computer
to
switch itself
off
at
specific times. Further-
more the PX-S can switch itself on, run a particular program and then switch
itself
on
again
to
run the same
or
another program. This ability
to
switch itself
on
and
off
is
a powerful feature
of
the computer.
To
switch the power
on
when the switch is already in the
on
position, switch
it
off
and on again. This means, holding the computer with the keyboard nearest
to
you, moving the switch towards you and then away from you again.
To switch the computer
off
when it is already in the
off
position, switch the
power switch
to
the
on
postion and then
off
again.
Because the computer can switch itself
on
and off, the power switch position
may not reflect the true state
of
the power.
For
example
if
the PX-S switches
itself off, the power switch will still be in the
on
position, even
th~ugh
t~e
po~
er
is
off. Similarly,
if
the PX-S switches itself on, the power
sWItch
wIll
be m
the
off
position even though the power
is
on. Holding the PX-S normally with
the keyboard towards you, the power switch
is
on
the right hand side
of
the
computer. The ON position
is
towards the back
of
the computer. The OFF po-
sition
is
towards the front
of
the computer.
2-18
There are also two
ways
to switch the power off: the restart and continue modes.
The selected mode
is
determined by the conditions prevailing at the time the
power
is
turned off. When the power
is
switched
off
in the restart mode, the
Menu or CP
1M
command line display
will
be activated when the power
is
turned
on
again. When the power
is
switched
off
in the continue mode, the operation
which
is
being executed when the power
is
turned
off
will be continued when
the power
is
turned on again.
i)
Conditions under which the restart mode
is
selected:
- When the power switch
is
turned off.
- When system initialization
is
performed.
- When the sub-CPU is reset.
- When the BIOS POWEROFF r:outine
is
called. (See Chapter
5)
ii) Conditions under which the continue mode
is
selected:
- When the power switch
is
turned
off
while pressing the I CTRl I key.
- When the auto power
off
time
is
reached, because no key has been
pressed. (See Chapter 3.)
- When the main battery voltage drops below a certain level
(power failure).
- When the BIOS POWEROFF routine
is
called.(See Chapter
5)
2-19
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