Philips PCL304 - Video Graphics Adapter; Video BIOS ROM; Power Supply; Power Low Indicator

2-4
2.2.7
Video
Graphics
Adapter
The
on-board
video
graphics
capability
is
incorporated
using
a
Cirrus
CL-GD610/620
graphics
controller.
The
controller,
with
256KB
of
video
memory
(2x256kx4
DRAM)
supports
VESA
1
(800x600
high
resolution
with
16
colors
from
a
pa-
lette
of
262,144
colors)
and
VGA
resolutions
and
is
also
backwards
compatible,
emulating
EGA,
CGA,
MDA
and
Her-
cules
graphics
standards.
2.2.8 Video BIOS ROM
The
video
BIOS
is
physically
situated
with
the
system
BIOS
ina
128KB
EPROM
on
the
motherboard.
The
logical
ad-
dress
for
this
BIOS
is
located
in
system
memory
area
E0000h
to
EFFFFh.
The
BIOS
supports
132
column
and
60
line
text
modes,
72x540
and
800x600
16-color
graphics
mode,
and
800x600
16-color
VESA
1
mode.
The
BIOS
accesses
are
limited
to
8-bit
accesses
unless
the
BIOS
is
shadowed
into
RAM
using
the
SETUP
program.
Then
the
accesses
are
of
16-bits.
2.3 Power supply
The
power
board
houses
a
sophisticated
power
manage-
ment
which
ensures
that
the
NiCad
battery
can
power
the
system
for
the
maximum
possible
time.
2.3.1 Power low indication.
Under
battery
power,
the
Notebook
will
automatically
moni-
tor
the
battery.
*
When
it
senses
that
the
battery
has
about
20
minutes
of
power
available,
the
power
LED
will
begin
to
blink
once
every
second,
and
the
system
buzzer
will
beep
twice
every
15
seconds.
At
this
warning
work
should
be
finished
within
about
10
minutes.
*
If
the
Notebook
senses
that
the
battery
power
is
critical,
the
power
LED
will
blink
twice
a
second
and
the
beeps
will
sound
four
times
every
ten
seconds.
Files
must
be
saved
immediately
to
disk(ette),
or
supply
AC
power.
*
Ifthe
battery
should
“die”
before
time
was
left
to
shut
down
the
Notebook,
the
system
would
have
automatically
po-
wered
down.
2.3.2 Recharging a battery
The
Notebook
always
checks
on
the
charge
level
of
the
bat-
tery
via
a
sophisticated
power
management
control.
When
the
system
is
running
under
AC
power
the
CHR/STB
LED
will
be
lit
to
show
that
the
battery
is
being
recharged
(stand-
by
mode
is
disabled
under
AC
power).
Remark:
NiCad
batteries
have
a
tendency
to
lose
capacity
in
case
they
are
not
fully
discharged.
In
other
words,
if
they
are
al-
ways
used
for
approximately
the
same
time,
such
as
100
mi-
nutes,
and
then
recharged,
they
will
hold
only
a
100
minute
charge.
No
more
charge
can
be
increased.
Once
this
situation
occurs,
it
can
not
be
corrected
by
simply
discharging
and
recharging
again.
This
Notebook
has
the
utility
to
solve
this
problem
by
using
the
program
"DPDISCHG"”.
After
running
the
"DPDISCHG"
utility
the
power
has
to
be
turn
off
and
on
again
for
normal
operation.
CS 55 801
2.3.3 Power conservation.
The Notebook offers numerous power conservation features
in order to prolong battery life to the maximum.
* Intelligent power saving
This feature is automatic and requires no control from the
user. It is functional at all times on battery power.
1. A slower rate of DRAM refresh is used.
2. The FDD will be monitered wether the drive is being
used. If not the FDD controller will be shut down. Any
instruction which requires access to the drive, the
FDD controller will automatically be "woken up”.
3. The CPU monitors its own activity. If no operation is ta-
king place, the PCU is slowered down from the 16Mhz
or 8Mhz rate to 4Mhz.
When CPU activity is resumed, the clock speed is auto-
matically returned to the original speed.
This feature will be overridden if the "Auto-standby
disable" option in the Setup utility is selected.
* Selectable power down.
This feature is encountered in the Setup utility.
For a preset “trip time” which is specified in the Setup uti-
lity the system can be instructed to shut down power con-
suming components.
1. Backlight power off:
Screen backlight is powered down if the LCD power
down time elapses with no srceen activity and no key
stroke.
2. LCD screen power off:
LCD screen is powered down if the LCD power down
time elapses with no srceen activity and no key stroke.
3. HDD power down:
The HDD power is shut down if the HDD power down
time elapses with no hard disk activity.
2.3.4 Stanby Mode
Standby mode is only available, and necessary, when batte-
ry power is used. In this node the amount of power required
by the system is greatly reduced.
Standby mode can be entered in two ways:
* Press the Standby mode switch.
* Closing the LCD cover without turning off the power.
In this case a warning beep will sound to indicate that the
power has not been sitched off.
The techniques used to conserve power in standby mode
are listed below.
* The clock speed is reduced to 4Mhz.
The HDD is powered down.
Screen backlighting is switched off.
The LCD screen is switched off.
The LCD controiler is powered down
Floppy disk controller is powered down.
Keyboard LEDs are turned off.
+ * + © &
When the system is in standby mode, the CHR/STB LED
will flash to alert the system condition.