SCR attack

On Mon, 2 Dec 2019 19:55:57 -0600, VanguardLH wrote:
Some users think a black (blank) screensaver consumes less power than an
all-white screensaver. They don't know how LCDs work. All all-black
screensaver consumes an itty bitty more power than an all-white
screensaver, because of the lack of having to apply power to twist the
polarizer to block the light from the LED. The backlamp is always on.
Whether you see it for a pixel depends on whether or not the polarizer
is energized. An energized polarizer consumes more power than a relaxed
polarizer.

I did not know that.

What about when the computer sleeps? I'm wondering specifically about
laptops. As far as the laptop screen is concerned, is computer sleep
equivalent to a black screensaver, or does the laptop screen actually
see less power (or no power) when the computer is asleep?


--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://BrownMath.com/
http://OakRoadSystems.com/
Shikata ga nai...

In message , Stan Brown
writes:
On Mon, 2 Dec 2019 19:55:57 -0600, VanguardLH wrote:
Some users think a black (blank) screensaver consumes less power than an
all-white screensaver. They don't know how LCDs work. All all-black
screensaver consumes an itty bitty more power than an all-white
screensaver, because of the lack of having to apply power to twist the
polarizer to block the light from the LED. The backlamp is always on.
Whether you see it for a pixel depends on whether or not the polarizer
is energized. An energized polarizer consumes more power than a relaxed
polarizer.

I did not know that.

What about when the computer sleeps? I'm wondering specifically about
laptops. As far as the laptop screen is concerned, is computer sleep
equivalent to a black screensaver, or does the laptop screen actually
see less power (or no power) when the computer is asleep?


Nearly always (I think always), when a laptop goes into any of the
low-power modes, the display backlight is turned off, which is the
largest component of the power consumption of the display. I _suspect_
the video output turns off too, but that's very much a second or third
order component compared to the backlight. (I guess you could find out
by connecting an external monitor and see whether _that_ goes off -
though the laptop may treat external displays differently.)

Incidentally, I've often wondered why no laptop uses ambient light. I
remember many years ago, where I worked had a Sony camera, whose back
display had a conventional backlight, but also a diffuser that continued
to a strip along the top: in sunny conditions, you could turn the
backlight off, but the display was perfectly visible by the daylight
being collected by this diffuser. (You may say it was only quite a small
display, but for the time it was quite large: the camera had a floppy
drive in it, and the display was about that size. Besides, a laptop
screen could have several such strips along the back, say two inches
apart.)
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

I don't like that word [atheist]; it implies that there's a god not to believe
in - Eric Idle, quoted in RT 2016/12/10-16

In article , Stan Brown
wrote:


What about when the computer sleeps? I'm wondering specifically about
laptops. As far as the laptop screen is concerned, is computer sleep
equivalent to a black screensaver, or does the laptop screen actually
see less power (or no power) when the computer is asleep?

sleep is effectively the same as off, except memory is maintained so it
can instantly wake. sometimes memory is written to the hard drive and
powered down, which takes slightly longer.

Stan Brown wrote:
On Mon, 2 Dec 2019 19:55:57 -0600, VanguardLH wrote:
Some users think a black (blank) screensaver consumes less power than an
all-white screensaver. They don't know how LCDs work. All all-black
screensaver consumes an itty bitty more power than an all-white
screensaver, because of the lack of having to apply power to twist the
polarizer to block the light from the LED. The backlamp is always on.
Whether you see it for a pixel depends on whether or not the polarizer
is energized. An energized polarizer consumes more power than a relaxed
polarizer.

I did not know that.

What about when the computer sleeps? I'm wondering specifically about
laptops. As far as the laptop screen is concerned, is computer sleep
equivalent to a black screensaver, or does the laptop screen actually
see less power (or no power) when the computer is asleep?

There has to be a means to turn off the backlight!

Sleep power should be limited to providing roughly 1 watt
per DIMM on a DDR3 or DDR4 machine. So when a computer
sleeps, the session is stored in DRAM, the DRAM still
receives power and a clock signal, and the DRAM is
issued an "autorefresh" command before parking.
An address counter runs inside the DIMM, to make sure
each location is visited at a regular rate, before
the charge on the floating gate, drains away.

If you want to get hours and hours out of the laptop
in S3 sleep, all other vampire loads have to be removed.
Then it's a matter of dividing the watt-hours of the battery
pack, by that few watts of load from the installed DRAM.

When the computer is running, two DIMMs sitting on the
same channel, one DIMM is in autorefresh (is drawing 1 watt),
the second DIMM executes higher power cycles (read or write).
Maybe the DIMM draws 3 watts for a higher power cycle. And
the DIMM doesn't have to do back-to-back higher power cycles
either, so that the average power is only a little higher
than autorefresh.

If you install DIMMs in dual channel mode, you pay extra
power for powering up the second channel, plus you have the
opportunity to leave the DIMM running in the higher power
state. While dual channel is important for giving "snappy
integrated graphics performance", you are actually paying
a price for that in terms of battery life. The CPU on the
other hand, when the computer is in S0, is really hammering
the battery, and these distinctions might be more important
on a tablet with a 10 hour battery life. A tablet with a 10
hour battery life, might be using a processor with a 2W SDP.
And now, the punishment the DIMMs provide, matters. A good
design will then only use a single channel (or in the case
of the cheapest Intel products, a "half-channel" 32 bits wide,
done with soldered-down RAM chips).

In S3, almost all primary power is removed. Only a little
sustaining power is provided, and that still requires
a switching converter. The backlight has to go off, since
the backlight could use as much power or more, than the DIMMs.

In S0 (what I think of as a "mostly useless" state),
they can implement that however they want. Yes, the
screen can go black, but they have options as to how
it can assume a black color. You can turn all the
pixels black, or, you can set the PWM on the backlight
to zero and cause the inverter to stop running. The
power to run a LED backlight, has to come from somewhere,
will use a switching converter, and the backlight also
needs modulation capability. If it uses a PWM signal,
you can have the PWM response curve pass through (0,0)
and get the desired lower power feature for free. The
PWM, when at a DC level, can be used to blank the display
by removing the light.

As for LCD displays, most of the displays we use are
transmission displays. But there are monochrome ones
which are reflective, and there are a few which are...
transreflective, and operate both modes, and those
are excellent in sunlight.

https://en.wikipedia.org/wiki/Transf...rystal_display

Paul

"JJ" wrote

| I'd suggest not associate it with `txtfile`, since by default, it will be
| opened using Notepad, and Notepad can be very slow when loading a binary
| file.

True, but I don't mind. Notepad is safe and having
it try to open the file would ensure that I become
aware something's amiss. It's doubtful that I'd ever
even make the mistake. The TXT association is just
insurance in case I'm not paying attention. And once
Notepad did get it open I'd be able to see that it
was EXE.

I've often wondered why Notepad gets so stumped.
It could just open it as ANSI. Maybe it goes in circles
trying to figure out what encoding it is? That would
make sense. It seems to me that the older,
non-unicode-aware Notepad had no trouble opening
an EXE as text.

On 03.12.19 15:35, Mayayana wrote:
"JJ" wrote

| I'd suggest not associate it with `txtfile`, since by default, it will be
| opened using Notepad, and Notepad can be very slow when loading a binary
| file.

True, but I don't mind. Notepad is safe and having
it try to open the file would ensure that I become
aware something's amiss. It's doubtful that I'd ever
even make the mistake. The TXT association is just
insurance in case I'm not paying attention. And once
Notepad did get it open I'd be able to see that it
was EXE.

I've often wondered why Notepad gets so stumped.
It could just open it as ANSI. Maybe it goes in circles
trying to figure out what encoding it is? That would
make sense. It seems to me that the older,
non-unicode-aware Notepad had no trouble opening
an EXE as text.


Install notepad++, that opens anything fast, and knows about a lot
of formats.

On Tue, 3 Dec 2019 12:01:40 +0000, J. P. Gilliver (John) wrote:
In message , Stan Brown
writes:
[quoted text muted]
equivalent to a black screensaver, or does the laptop screen actually
see less power (or no power) when the computer is asleep?


Nearly always (I think always), when a laptop goes into any of the
low-power modes, the display backlight is turned off, which is the
largest component of the power consumption of the display. I _suspect_
the video output turns off too, but that's very much a second or third
order component compared to the backlight. (I guess you could find out
by connecting an external monitor and see whether _that_ goes off -
though the laptop may treat external displays differently.)

Thanks, John, and thanks also to Paul.


--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://BrownMath.com/
http://OakRoadSystems.com/
Shikata ga nai...

"Mayayana" on Mon, 2 Dec 2019 21:49:05 -0500
typed in alt.windows7.general the following:
"VanguardLH" wrote

| How many users lock their computer before leaving it powered? A
| screensaver can be configured to lock the workstation after an idle
| timeout.

News to me. I've never worked in an office or
needed a computer anywhere but home. If I'm
using it it's on. If I take a break it's on standby.
Otherwise it's off. In none of those situations
would a screensaver be relevant. I've also never
had a computer configured to go into standby
or activate a screensaver after a period of inactivity.
I never used a screensaver with a CRT, either, but
I didn't leave it turned on. There was no reason
to do so. But I can see how it might be different
if you're not at home.

I have a password on my account. The only human in the place was
me. "Just something to keep the cat from going online."

--
pyotr filipivich
Next month's Panel: Graft - Boon or blessing?

On 12/2/19 2:59 PM, Mayayana wrote:
Just a note about a current attack. I just got an email
with an attached .SCR. No message. Screensaver!
I'd forgotten those existed.

I changed HKCR\.scr default value to "txtfile" and deleted
HKCR\scrfile\

I don't know of any reason for screensavers to still exist.
I certainly don't use them.

AFAIK, LCD monitors don't have the problem a screen saver is meant to
solve. If you want to save power there's better ways than a program that
demands additional CPU time.

--
22 days until the winter celebration (Wed, Dec 25, 2019 12:00:00 AM for
1 day).

Mark Lloyd
http://notstupid.us/

"We cannot hope for a society in which formal organized religion dies
out. But we can stop behaving as if it was worthy of our collective
respect." [A. N. Wilson, "Against Religion"]

"pyotr filipivich" wrote

| I have a password on my account. The only human in the place was
| me. "Just something to keep the cat from going online."

That's why I no longer have a cat. They have a way
of racking up charges on gaming sites. I actually have
a BIOS password, so someone can't start the computer
when I'm not here. But it's not really critical. I don't
bank or shop online. There are no credit card or
account numbers to find.

But I guess that's one way I do things differently from
most people. I not only don't bank online but I also don't
leave my computer on when I'm out. It seems like most
people rarely if ever turn off their computer. That seems
crazy to me. I shut it off every night. The 30 second boot
doesn't bother me.

"Sjouke Burry" wrote

| Install notepad++, that opens anything fast, and knows about a lot
| of formats.

Yes, I have that. A very solid piece of software.
But I only use it rarely, for gigantic files. It's
overkill for what Notepad can do and it's not nearly
specialized enough for any kind of coding I do. The
whole thing is really just a simple wrapper for the
Scintilla RichEdit control, which is a solid but general
purpose edit window. Like so many editors, they claim
support for dozens of programming languages. Like
so many editors, by being a jack of all codes they're
a master of none.

So N++ has become my program for reading the
occasional 100 MB text file.

VanguardLH wrote:

VanguardLH wrote:

Just because you have done so, ...

Oops. Should be "Just becasue you have not done so, ..."
^^^

ARGH!!!! ^^^^^^^___ because

Damn fingers won't do what I tell them to do.

Mayayana wrote:
"pyotr filipivich" wrote

| I have a password on my account. The only human in the place was
| me. "Just something to keep the cat from going online."

That's why I no longer have a cat. They have a way
of racking up charges on gaming sites. I actually have
a BIOS password, so someone can't start the computer
when I'm not here. But it's not really critical. I don't
bank or shop online. There are no credit card or
account numbers to find.

But I guess that's one way I do things differently from
most people. I not only don't bank online but I also don't
leave my computer on when I'm out. It seems like most
people rarely if ever turn off their computer. That seems
crazy to me. I shut it off every night. The 30 second boot
doesn't bother me.

It's a good idea to turn off Windows 10, because
it has a bad habit of waking up whenever it feels
like it, and doing God knows what.

Paul

On 12/3/2019 12:46 PM, Mayayana wrote:
"pyotr filipivich" wrote

| I have a password on my account. The only human in the place was
| me. "Just something to keep the cat from going online."

That's why I no longer have a cat. They have a way
of racking up charges on gaming sites. I actually have
a BIOS password, so someone can't start the computer
when I'm not here. But it's not really critical. I don't
bank or shop online. There are no credit card or
account numbers to find.

But I guess that's one way I do things differently from
most people. I not only don't bank online but I also don't
leave my computer on when I'm out. It seems like most
people rarely if ever turn off their computer. That seems
crazy to me. I shut it off every night. The 30 second boot
doesn't bother me.


I agree the safest computer is one that is not on. I turn my computers
off when not in use.

On 12/3/2019 5:38 PM, Paul wrote:
Mayayana wrote:
"pyotr filipivich" wrote

| I have a password on my account.Â* The only human in the place was
| me.Â* "Just something to keep the cat from going online."

Â*That's why I no longer have a cat. They have a way
of racking up charges on gaming sites. I actually have
a BIOS password, so someone can't start the computer
when I'm not here. But it's not really critical. I don't
bank or shop online. There are no credit card or
account numbers to find.

Â* But I guess that's one way I do things differently from
most people. I not only don't bank online but I also don't
leave my computer on when I'm out. It seems like most
people rarely if ever turn off their computer. That seems
crazy to me. I shut it off every night. The 30 second boot
doesn't bother me.

It's a good idea to turn off Windows 10, because
it has a bad habit of waking up whenever it feels
like it, and doing God knows what.

Â*Â* Paul
Putting the computer in the sleep mode is not the same as turning off
the computer. To my knowledge there is no software that can activate
the hard ware switch.