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OT: Can CMOS battery on PC motherboard be hot-swapped?

S

SoothSayer

11000km in <2ms ! I don't think so.


With a hard modem, the connection you get is timed. They account for
the entire trip time, and even for your serial port latency, and the
resultant determination as way more accurate than Any NTP method EVER
was. Phones even used satellites, and they compensated for that "hop"
too.

So you jump to conclusions without knowing what men did back then.
Yes... I think so.

The NTP "utilities" take several samples and picks the most commonly
returned result. They bounce around so much, you get a different result
every time. Just pay attention and it is easy to see. It sets the time
differently every time.

Call these NIST guys with a modem, and your hard link will get you
consistent sub 5ms time sets.

That is what it was/is meant for.

IIRC, there is a similar phone line set-up over on that half.
 
J

Jasen Betts

With a hard modem, the connection you get is timed. They account for
the entire trip time, and even for your serial port latency, and the
resultant determination as way more accurate than Any NTP method EVER
was. Phones even used satellites, and they compensated for that "hop"
too.

Ah, I thought were proposing to just dial some tty "time of day"
service and subtract the time it takes to clock the bits through the
UART.
The NTP "utilities" take several samples and picks the most commonly
returned result. They bounce around so much, you get a different result
every time. Just pay attention and it is easy to see. It sets the time
differently every time.
Call these NIST guys with a modem, and your hard link will get you
consistent sub 5ms time sets.

I get that from NTP already.
IIRC, there is a similar phone line set-up over on that half.

half=hemisphere?

Yeah, I think I dialed it once or twice, when it was a free call.
it was very similar to what I have read about ACTS. It appears
to have been discontinued.
 
J

JW

[snip]


That's odd. Because the PC here is always sent to hibernate and the
power is turned off. But it remains connected to 120VAC. Still, this
morning the RTC was off again by more than five minutes from yesterday.


[snip]

RTC's are often rather crappy.

I use Socketwatch from...

http://www.robomagic.com

I'm currently within 50ms of UTC/

That's $10. I use Time synchronizer from Softnik Technologies. Better yet,
it's free. http://time-synchronizer.software.informer.com/

Sounds like that synchronizer is functional only at boot or
manually...

"A simple time synchronizer that may be configured to startup at
Windows boot, automatically connect to an atomic clock based time
server, synchronize the system clock and then quit."

My machines run 24/7. My Socketwatch set-up automatically
synchronizes every 60 minutes (you can set it to any interval you
want).

It can be configured to run in the system tray and update the clock at any
interval you choose with any timeserver you want.
Socketwatch also has a convenient tool to synchronize your watch to
the second... count down and "beep-beep-beep-BOING" like the old time
signals on your AM radio.

Doesn't do that, though...
 
M

miso

Your claim of 20ms is falsely based. Do it 25 times, and I'll bet you
get 25 different offsets from the real. So more likely plus or minus
about 80ms. You could probably get closer by hand synching to your phone
with the mouse click.

Are you that "always wrong" asshole?

I plotted the data. I know the results. The accuracy depends on your
system. The RTC stability, temperature/tempco, system load, etc. That is
why I said you have to plot the error relative to time of day.

Learn something. Here is a good source of NTP tracking tools:

Next time educate yourself before you post nonsense.
 
M

miso

While I'm busy bitch slapping this moron, why you do nowadays is use a
GPSDO, which I also have though don't bother to use for system time.

I doubt anyone uses a modem. If you don't GPSDO, you can use a cellular
network for a time sync.
 
J

josephkk

[snip]
That's odd. Because the PC here is always sent to hibernate and the
power is turned off. But it remains connected to 120VAC. Still, this
morning the RTC was off again by more than five minutes from yesterday.
[snip]

RTC's are often rather crappy.

I use Socketwatch from...

http://www.robomagic.com

I'm currently within 50ms of UTC/

...Jim Thompson

You do not need an addon since Win2000/XP they do ntp natively, should be
within 1 ms or better.

?-)
 
M

MrTallyman

[snip]
That's odd. Because the PC here is always sent to hibernate and the
power is turned off. But it remains connected to 120VAC. Still, this
morning the RTC was off again by more than five minutes from yesterday.
[snip]

RTC's are often rather crappy.

I use Socketwatch from...

http://www.robomagic.com

I'm currently within 50ms of UTC/

...Jim Thompson

You do not need an addon since Win2000/XP they do ntp natively, should be
within 1 ms or better.

?-)

ntp does NOT get you "within 1ms or better".

And getting that is happenstance, not accurate, repeatable utility.

That is why each time you do it, you get a different offset.

You would first require the aptitude to see where the error gets
introduced to begin with, however.
 
J

josephkk

Why does the change have to be quick? Isn't the circuit powered as long
as the laptop is? Because then one could solder in a new battery and
re-use the connector instead of shelling out lots of dough for a
specialty battery plus shipping charges.

Hey, it's nice, this morning the PC showed the correct time again :)

What I really don't understand why in this day and age they don't write
the settings into flash. I mean, we even successfully do that on totally
cheapo uC design.

I kinda hate be snotty here but, since when is time a constant value? The
battery is to keep the clock running. Replacement cycles should be
similar to most watch batteries.

?-)
 
J

josephkk

Drivel: Many years ago, I decided that I wanted GPS accuracy on my
office Unix server. I took the NEMA 183 output from an old Garmin 65
GPS, parsed the data with a shell script, and reset the PC clock
according to the GPS time. What I forgot to include was a sanity
check on the data. When the receiver lost sync, the GPS would produce
00:00:00 etc as the current time. It took a while to clean up my log
files and recover from that mistake. This is another reason why I
don't do much programming.


Here's what's stored in the CMOS:
<http://www.bioscentral.com/misc/cmosmap.htm>
Note that the first few bytes are the RTC current time and date (but
not the TZ time zone). This info gets written to the CMOS chip once
every second. If that were flash memory with an optimistic 100,000
write/erase cycles, the flash chip would be dead in several days.

Way back in the early days of XTs you actually find the logic that
segregated those addresses from actual memory to the clock chip. Been
that way ever since.

?-)
 
J

josephkk

True. It's the clock and status registers below 0Fh that get
scribbled to constantly. One could split the CMOS function in half,
with the lower half continuing to be CMOS, while the rest is changed
to flash. However, that will add front end cost and additional
complexity, which are not good things.

Actually that change has already occurred. And as stated before the few
bottom addresses do not access CMOS/FLASH but the clock chip (portion)
itself. Check the specifications for a south bridge chip.

?-)
 
J

josephkk

Wouldn't it be a zero-cost piece of cake to at least write those to hard
disk and in case of finding a blank offer the user to restore from
there? Also, the BIOS is in flash so why not store there instead?

The "CMOS" has long ago gone to flash onboard the southbridge chip.
It would behove the industry to think about this because there is one
major reason why PC sales are slumping: The things became to darn
complicated for ol'Leroy. He does not want to face a pricey Geek Squad
call every time some obtuse "unrecoverable error" has occurred. So he
invests his money into a smart phone instead. Because that's not
complicated. A PC is complicated.

I think you really missed the boat on this one. Desktops in the home has
hit saturation, but laptops for students and many other travel prone
people is still growing. My latest laptop might be able to eat your 2
year old desktop for lunch performance wise; it is a real screamer.

?-)
 
J

Joerg

josephkk said:
The "CMOS" has long ago gone to flash onboard the southbridge chip.

I think you really missed the boat on this one. Desktops in the home has
hit saturation, but laptops for students and many other travel prone
people is still growing. My latest laptop might be able to eat your 2
year old desktop for lunch performance wise; it is a real screamer.

And after 2h the fun is over, battery exhausted. I do heavy SPICE and a
laptop won't last long that way. The HD writes for the RAW files alone
are a major burden.

But what I meant was PC sales in general, including laptops. Many older
folks buy laptops these days because they don't want a space-hogging
tower and monitor setup. And it's the saem thing there: Writing setup
info that hardly ever changes into voltaile RAM is not smart.
 
J

Joerg

josephkk said:
I kinda hate be snotty here but, since when is time a constant value? The
battery is to keep the clock running. Replacement cycles should be
similar to most watch batteries.

I meant all the other settings. Think about it a little more: Why does
the handbook insist you copy everything in the setup before swapping the
battery? They would surely not say that if all you'd lose is date and
time (which nowadays cen even be auto-updated from the web).
 
G

G. Morgan

Joerg said:
Folks,

Got a Dell Vostro 200 mini tower with XP on there that seems to be a bit
off in the realtime clock lately. Around five years old so needs a new
3V coin cell on the mobo.

In order not to lose all the setup stuff, can those CR2032 coin cells be
hot-swapped while the PC is running?

Of course using ESD straps, being careful and all that.


Yes. Just be careful not to drop it on a energized circuit board!
 
S

SoothSayer

Yes. Just be careful not to drop it on a energized circuit board!


The strap or the battery? The strap is NOT the degree of "conductive"
you may think it is.

Unless you are dumb enough to have ever or still be using those stupid
"wrist watch strap" designs that were metallic. The cloth ones pass
tests for years as fully functional.

But as for ESD and keeping your products safe from yourself...

The paradigm these days, since fields are also important to abate as
well, is to simply don an ESD smock and be shielded full body. nothing to
drop onto anything, including a charged field. Touch your product
chassis or workbench ground before starting.

Also, your skin is (typically) very dry (comparatively)and you can
accumulate excess electrons (charge) on it with respect to an earth
grounded chassis from your clothing. Moisturize your hands and writs,
since that is where the smocks connect to you at.

Other "charge particulars"

Even an ungrounded chassis is already typically at earth grounded (read
'drained') potential, as it was at one time so grounded and not likely to
have had charges added to it. It will sink your charge. If you only
touch the chassis. You AND the chassis are important to establish being
at the same charge. Do not use electrical ground for ESD abatement
systems. Earth sink points, as in a hard driven ground rod are
preferred.

So, FAIAP even an ungrounded system or chassis is considered "at ground
potential" because it was recently or still is, from an ESD sinking
capacity POV.

Of course there are special situations where an earth ground insulated
(ungrounded) chassis, like one sitting on a table, could build a charge
over the entire chassis with respect to true earth ground, as in a
location where magnetic fields from HV presence or corona or even dry air
in a lightning storm area. Or just dry air.

But for the most part, even an ungrounded chassis is considered "at
ground" and represents the same ESD event sinking capacity as a fully
grounded system.

After many such 'sinking' events, however, one would think that the
chassis itself might have a few extra electrons that might want to jump
into the earth when that contact was re-established.

So back to the smocks.

They now have integrated "wrist straps" because they are long sleeved
and the sleeves have conduction throughout the smock, and the 'ground
lead' gets attached at the left or right pocket, mid smock.

No wrist strap required and no fields are ever present when someone
touches ground as they approach an ESD controlled workstation, and then
hooks up before any examinations or functions utilizing ESD susceptible
componentry is performed. It is all about balance. Typically, the
'ground circuit' of any device or card or circuit you would consider
touching is the ground level of the surface of your bench top, and YOU
yourself.

Otherwise, your PC chassis IS the "ESD safe workstation", and you
either leave it plugged in, or tie the chassis to the electrical fault
line, since you have no ground rod *at* the PC. still, don the smock,
and use the PC chassis as your smock grounding point.

THAT IS THE IMPORTANT MESSAGE OF THIS POST.

For the smocks;

Plug in at a std test station and press the button, and the circuit
from the ground point, through the ESD attachment cord, to the smock
pocket, through the smock, sleeve, and cuff, into your wrist and down
through your finger, back to the button.

A passed test shows that not only is there a path to ground for your
body, but also a 'field shield' over your clothing, all integrated
together to keep you from presenting yourself as an ESD event hazard to
any device with such a susceptibility.

Remember, an ESD event and subsequent failure mode in a product does
NOT require contact, and does NOT always immediately exhibit any evidence
of the damage it has caused.
 
J

Joerg

Jim said:
Not enough memory?

There is never enough memory.

"Data Compression" not turned on?

No ability to "Save Data at Markers Only" ?>:-}

With switchers one usually doesn't want to do that. You never know where
"fuzz" shows up you want to look at and zoom in.

But I rarely run simulations on battery... that's what they make power
adapters or docking stations for ;-)

I thought that's what they make nuclear power stations for :)

But anyhow, I only use laptops for that if I have to. The heat generated
internally ain't too healthy for them.

Whine, whine, whine ;-)

Nah, if something in a consumer or business product got screwed up I
call that out. Thanks to Jeff I found that hot-swapping avoids having to
re-enter all that.
 
And after 2h the fun is over, battery exhausted. I do heavy SPICE and a
laptop won't last long that way. The HD writes for the RAW files alone
are a major burden.

Plug it in. Your desktop isn't going to work for very long if it's
unplugged either. Most people scale back their processing power
substantially when operating on battery. Two hours is a thing of the
past.
But what I meant was PC sales in general, including laptops. Many older
folks buy laptops these days because they don't want a space-hogging
tower and monitor setup. And it's the saem thing there: Writing setup
info that hardly ever changes into voltaile RAM is not smart.

Who does that, with flash being so ubiquitous?
 
J

Joerg

[...]
But what I meant was PC sales in general, including laptops. Many older
folks buy laptops these days because they don't want a space-hogging
tower and monitor setup. And it's the saem thing there: Writing setup
info that hardly ever changes into voltaile RAM is not smart.

Who does that, with flash being so ubiquitous?


Jeff brought an example, I don't know which mfgs use this:

http://www.bioscentral.com/misc/cmosmap.htm#

I have a Dell and the manual states that an image of the CMOS should be
taken before removing the battery, in order to be able to restore the
settings in there. But it fails to say how and what software to use for
this.
 
S

SoothSayer

[...]

But what I meant was PC sales in general, including laptops. Many older
folks buy laptops these days because they don't want a space-hogging
tower and monitor setup. And it's the saem thing there: Writing setup
info that hardly ever changes into voltaile RAM is not smart.

Who does that, with flash being so ubiquitous?


Jeff brought an example, I don't know which mfgs use this:

http://www.bioscentral.com/misc/cmosmap.htm#

I have a Dell and the manual states that an image of the CMOS should be
taken before removing the battery, in order to be able to restore the
settings in there. But it fails to say how and what software to use for
this.

Maybe just write down the settings? There's not very many.

...Jim Thompson

One of the best points in the entire thread.
 
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