Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

Maybe the same reason we didn't have built-in clocks until after there
were five dollar LCD wris****ches. I don't know.

My current clock is very accurate (MSI mainboard).

wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

In article . com,
says...
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

The short answer is that computer makers don't care.

More specifically, even cheap watches usually have a trimmer
capacitor on the timebase crystal that someone actually adjusts.
Computer makers usually choose to save pennies by using a fixed
capacitor and not having to pay labor to adjust.

wrote:
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.


Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.
Vendors care if you send it back. They don't care if you
bitch on the internet.
mike

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wrote:
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

I've often wondered the same thing...also why a $9 alarm clock will have
provision for battery backup, but $200 VCR (back when VCRs were $200)
needed to be rweset with each blip in the mains voltage.

FWIW, there are utilities which will update your computer clock from the
National Bureau of Standards over the web.....

jak

On 26 Oct 2005 15:03:04 -0700, wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

That question have been around for more than 20 years and probably
longer. Even one PC magazine reported a major branded PC that used to
cost $2,000 couldn't keep time as well as a $5 watch from Kmart (not
exact quote but similiar to that)

The OS could check via internet at regular intrevials to make
correction to the clock but that is if the PC does have internet
connection at all.
--
When you hear the toilet flush, and hear the words "uh oh", it's already
too late. - by anonymous Mother in Austin, TX
To reply, replace digi.mon with phreaker.net

somebody wrote
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

Who is the manufacturer? I only use Gigabyte(mostly) or MSI (sometimes)
motherboards. I find the clocks to be reasonably accurate. My guess
would be that the OEM didn't ground the crystal case or use the proper
guard ring techniques for noise reduction. Do you find that they run
fast or slow?

wrote:
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.



I have one PC that will lose or gain hours at a time if the machine goes
into standby, another that does ok but still drifts enough that I have
to use a utility to keep it in sync with the atomic clock. On the other
hand a Sun workstation that I fire up occasionally to play with keeps
excellent time, even after sitting unplugged for 6 months it's usually
within a few seconds but then it was originally $25K.

In article . com,
wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.


Dunno if it's still true in PC-land - I've been living in a Mac world
for a LONG time now - but when I was playing with them years ago, the
battery-backed real-time clock was read once at startup to set the
computer's software clock, which then kept time by counting clock
interrupts generated by the motherboard timing circuitry. That
interrupt, like any other "not non-maskable" interrupt, can be blocked
out for various reasons by various things, causing the software clock to
lose time. Usually, the amount of "lost" time isn't really noticable
except on "continuously on" machines. But with long periods between
restarts, heavy use of software (or firmware... The blame may not be in
your clock, but in your ROM code) that disables interrupts often or for
extended periods, and/or no intervention (be it human or software)
happening, it can grow to substantial amounts of time surprisingly quick.

Immediately after startup, the clock SHOULD be reasonably close to
right, since it will have been freshly set from the battery powered
clock, but after a while, it *WILL* go wonky unless steps are taken to
correct the drift - It's just the nature of the beast.

--
Don Bruder - - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... http://www.sonic.net/~dakidd for more info

Same reason El Cheapo watches don't run Windows!!

On 26 Oct 2005 15:03:04 -0700, wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

mike wrote:

Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.

I'm looking for a techical explanation.

James Sweet wrote:

I have one PC that will lose or gain hours at a time if the machine goes
into standby, another that does ok but still drifts enough that I have
to use a utility to keep it in sync with the atomic clock. On the other
hand a Sun workstation that I fire up occasionally to play with keeps
excellent time, even after sitting unplugged for 6 months it's usually
within a few seconds but then it was originally $25K.

The only PC motherboards I've seen that consistently kept accurate time
all had Dallas clock chips in them, and some of those chips were still
running properly from their internal lithium cells (permanently
encapsulated) 10 years later.

Most older motherboards used the Dallas real-time clock chip, which had
a cheapo oscillator built in, and could use an external crystal for
precision timekeeping. A good crystal will add a couple of dollars to
the price of the motherboard, but the clock ic itself was over ten
bucks. I use these chips in some other pieces of equipment and they are
very accurate when given a good crystal for a timebase.

I don't know what they put on modern motherboards. I throw computers
out when they stop working now.

However, the datasheet for the Dallas chip gives some hints that may be
useful here. If the chip is put in an electrically noisy device like a
computer, it can be accelerated by stray signals picked up by the clock
circuit. I believe that NTP machines (usually) set the RTC on shutdown,
as the cpu is more likely to be on time if it's been syncing itself
with an atomic standard.

wrote:
James Sweet wrote:


I have one PC that will lose or gain hours at a time if the machine goes
into standby, another that does ok but still drifts enough that I have
to use a utility to keep it in sync with the atomic clock. On the other
hand a Sun workstation that I fire up occasionally to play with keeps
excellent time, even after sitting unplugged for 6 months it's usually
within a few seconds but then it was originally $25K.


The only PC motherboards I've seen that consistently kept accurate time
all had Dallas clock chips in them, and some of those chips were still
running properly from their internal lithium cells (permanently
encapsulated) 10 years later.



Yeah the Sun has a Dallas in it, in fact I had to hack in a new battery
in one of them as the original went dead and modern chips won't work in
it. Come to think of it I had a 486 PC with a Dallas, I think that was
the most recent though.

Watches have an internal capacitor to adjust for each
crystal. I have never seen that capacitor on motherboards
since (I believe it was) the IBM AT. Furthermore, the PC
clock operates at two significantly different voltages that
will change crystal frequency. Battery voltage and voltage
when PC is powered will cause additional fluctuation. Which
voltage should they adjust the capacitor to? Just easier to
not install and adjust the capacitor.

wrote:
I'm looking for a techical explanation.

On Wed, 26 Oct 2005 17:46:28 -0500 jakdedert
wrote:

wrote:
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

I've often wondered the same thing...also why a $9 alarm clock will have
provision for battery backup, but $200 VCR (back when VCRs were $200)
needed to be rweset with each blip in the mains voltage.

I recently discovered that early Sony Beta VCRs (at least) actually
had back-up NiCad batteries which would keep the clock going for
seveeral minutes of blackout. I just replaced one today, with a NiMH,
and will replace a couple more in the next few days.

I'm sure I knew about these at one time, but I just forgot about them
until other things got me lnside that VCR again.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

On 26 Oct 2005 15:03:04 -0700 wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

There are 2 causes.

The first cause is that the internal clock (real time clock) on the
motherboard is a device which the motherboard manufacturer much buy
from someone else. They can buy this item in various degrees of
precision, but the cost goes up as you request more precision. Since
there is lots of pressure to keep cost down, but not so much pressure
to keep good time, the motherboard manufacturers don't press for
highly accurate real time clocks.

The second reason was explained by someone else. It's the fact that
the OS clock can fall behind the real time clock due to the way the OS
is written. This error is minimal when your computer is first booted
up, but it can become significant if it is left running for days. This
error is reset to zero each time you reboot.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

Well I can't answer your question but for those who don't know, XP has
an automtic time synchronization feature which operates weekly. You
have to be on line of course. The synchronization can also be done
manually. See: StartControl PanelDate and Time. My pc keeps time
very well.

Glenn

On 26 Oct 2005 15:03:04 -0700, wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

On Wed, 26 Oct 2005 23:25:49 GMT, Don Bruder wrote:



Dunno if it's still true in PC-land - I've been living in a Mac world
for a LONG time now - but when I was playing with them years ago, the

I've always wondered why the batteries in macs run down so quickly. I
rarely see a PC newer than 10 years old with a bad battery, but I
consistently see 3-5 year old macs with totally dead clock batteries.
Macs even have a much larger (and more expensive) lithium cell than
most PCs. I've seen a few 15 year old 486's with the same type and
brand battery used by apple that still measures full voltage.

I think the answer to the original question is just no quality control
for clock accuracy. My current PC is pretty accurate, but it's still
not as good a cheap watch.
Andy Cuffe

-- Use this address until 12/31/2005

-- Use this address after 12/31/2005

In message Jim Adney
wrote:

On 26 Oct 2005 15:03:04 -0700 wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

There are 2 causes.

The first cause is that the internal clock (real time clock) on the
motherboard is a device which the motherboard manufacturer much buy
from someone else. They can buy this item in various degrees of
precision, but the cost goes up as you request more precision. Since
there is lots of pressure to keep cost down, but not so much pressure
to keep good time, the motherboard manufacturers don't press for
highly accurate real time clocks.

And at the end of the day, most users have internet access these days,
so it's less critical since the clock will be updated by most modern
operating systems automatically.

The second reason was explained by someone else. It's the fact that
the OS clock can fall behind the real time clock due to the way the OS
is written. This error is minimal when your computer is first booted
up, but it can become significant if it is left running for days. This
error is reset to zero each time you reboot.

It's worth noting that an OS can correct for this too, either by using
an external time source when available, or periodically resynchronizing
from the BIOS clock if no reliable external source is available.

--
Is it my imagination, or do buffalo wings taste like chicken?

" bravely wrote to "All" (26 Oct 05 17:46:23)
--- on the heady topic of " Why aren't computer clocks as accurate as cheap
quartz watches?"

do From:
do Xref: core-easynews sci.electronics.basics:145600
do sci.electronics.repair:346372 alt.comp.hardware.pc-homebuilt:351220

do mike wrote:

Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.

do I'm looking for a techical explanation.


CHANGE THE XTAL, ALREADY!!!

A*s*i*m*o*v

.... Techs would rather pee on an electric fence for the light show

On Wed, 26 Oct 2005 23:25:49 GMT, Don Bruder put
finger to keyboard and composed:

In article . com,
wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.


Dunno if it's still true in PC-land - I've been living in a Mac world
for a LONG time now - but when I was playing with them years ago, the
battery-backed real-time clock was read once at startup to set the
computer's software clock, which then kept time by counting clock
interrupts generated by the motherboard timing circuitry.

It's true for Win98, but I don't know about XP.

Just for fun, here's something interesting that I discovered recently:

http://groups.google.com/group/comp....e=source&hl=en

I could make time run backwards on a Win98SE machine by doing
something innocuous.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

wrote:
mike wrote:

Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.


I'm looking for a techical explanation.


Very often, the economic or political considerations
dwarf any technical consideration.
The technical explanation is that they do what's cheap.
Wishing for a grand technical reason won't make it so.
mike

--
Wanted, Serial cable for Dell Axim X5 PDA.
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
htremovethistp://www.geocities.com/SiliconValley/Monitor/4710/

"mike" wrote in message ...
wrote:
mike wrote:

Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.


I'm looking for a techical explanation.


Very often, the economic or political considerations
dwarf any technical consideration.
The technical explanation is that they do what's cheap.
Wishing for a grand technical reason won't make it so.
mike

You seem to be saying curiosity is a worthless trait.

I bet you're a republican.

In article ,
Andy Cuffe wrote:

On Wed, 26 Oct 2005 23:25:49 GMT, Don Bruder wrote:



Dunno if it's still true in PC-land - I've been living in a Mac world
for a LONG time now - but when I was playing with them years ago, the

I've always wondered why the batteries in macs run down so quickly. I
rarely see a PC newer than 10 years old with a bad battery, but I
consistently see 3-5 year old macs with totally dead clock batteries.

I'm not absolutely certain on that myself, though many explanations have
been put forth over the years, with the one I think is probably "the
real situation" being that Macs (A) Don't cut the battery out of the
circuit when powered up and (B) the battery isn't just keeping the RTC
running, but also keeping a chunk of memory (which we call "PRAM" here
in Mac-land - holds various fairly-to-really critical information) alive.

Macs even have a much larger (and more expensive) lithium cell than
most PCs. I've seen a few 15 year old 486's with the same type and
brand battery used by apple that still measures full voltage.

I don't know for certain about measured voltage, but I've only actually
*NEEDED* (as opposed to "shotgunning" a startup issue) to replace one
battery in my stops to count Hmmm... I guess that would be about 8
Macs over the last 15 years or so. That was in a Performa 637CD that I
picked up at a thrift store for ten bucks. The machine I'm typing on, a
PowerMac 7500, came to me secondhand also, and as far as I have any way
to know, it's still running on the factory-installed battery - 10+ years
since it came off the line.

--
Don Bruder - - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... http://www.sonic.net/~dakidd for more info

Mike Foss wrote:
"mike" wrote in message ...

wrote:

mike wrote:


Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.


I'm looking for a techical explanation.


Very often, the economic or political considerations
dwarf any technical consideration.
The technical explanation is that they do what's cheap.
Wishing for a grand technical reason won't make it so.
mike


You seem to be saying curiosity is a worthless trait.

Nope, I'm saying insisting on technical explanations for economic
decisions is a worthless trait.
Anybody with a wrist likely understands that it's possible to keep
accurate time. If computer users rated it high in their purchase
decision, you'd see very accurate clocks.
It's all about the Benjamins...

I bet you're a republican.

I'll check my voter registration and get back to you.
mike




--
Wanted, Serial cable for Dell Axim X5 PDA.
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
htremovethistp://www.geocities.com/SiliconValley/Monitor/4710/

"mike" wrote in message ...
Mike Foss wrote:
"mike" wrote in message ...

wrote:

mike wrote:


Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.


I'm looking for a techical explanation.


Very often, the economic or political considerations
dwarf any technical consideration.
The technical explanation is that they do what's cheap.
Wishing for a grand technical reason won't make it so.
mike


You seem to be saying curiosity is a worthless trait.

Nope, I'm saying insisting on technical explanations for economic
decisions is a worthless trait.
Anybody with a wrist likely understands that it's possible to keep
accurate time. If computer users rated it high in their purchase
decision, you'd see very accurate clocks.

File that one under D for DUH.

The OP was asking for a technical explanation, and so far the
responses have been enlightening. Well, except for yours.

On Wed, 26 Oct 2005 18:51:12 -0400, Impmon wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

That question have been around for more than 20 years and probably
longer. Even one PC magazine reported a major branded PC that used to
cost $2,000 couldn't keep time as well as a $5 watch from Kmart (not
exact quote but similiar to that)

The OS could check via internet at regular intrevials to make
correction to the clock but that is if the PC does have internet
connection at all.


http://www.tucows.com/downloads/Wind...Synchronizers/

Mike Foss wrote:
"mike" wrote in message ...

Mike Foss wrote:

"mike" wrote in message ...


wrote:


mike wrote:



Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.


I'm looking for a techical explanation.


Very often, the economic or political considerations
dwarf any technical consideration.
The technical explanation is that they do what's cheap.
Wishing for a grand technical reason won't make it so.
mike


You seem to be saying curiosity is a worthless trait.

Nope, I'm saying insisting on technical explanations for economic
decisions is a worthless trait.
Anybody with a wrist likely understands that it's possible to keep
accurate time. If computer users rated it high in their purchase
decision, you'd see very accurate clocks.


File that one under D for DUH.

The OP was asking for a technical explanation, and so far the
responses have been enlightening. Well, except for yours.


There is no technical explanation except that the technology that
is being used does not guarantee accurate clocks.

If you do the math, you'll uncover the fact that a wris****ch is
phenomenally accurate compared to a RTC crystal.

I haven't been responsible for a computer design since 1989. Back
in the day, the philosophy was, "design for the center of the
statistical distribution and fix it in software."
Fortunately, UINX was smart enough to do time correction.

I haven't been responsible for a frequency counter design group since
1975. Back in the day, the philosophy was, "use the cheapest timebase
that guaranteed the specified accuracy."

I've had motherboards where they saved a nickel by leaving off the two
caps on the Xtal. Adding the caps helped, but "net time" fixed it in
software.

Are we seeing a trend yet?
You can get any accuracy you're willing to pay for. Computer users have
voted with their wallets for "lousy". I don't remember ever seeing a
specification for real time clock accuracy on a motherboard.
So if the clock ticks, it's in spec. Statistically, you'll sometimes
get one that's unacceptable and some of those will get bitched about on
the internet. It's the same reason that sometimes your Ford won't run
right.

You're the Chinese engineer. Go tell the bean counter that you want to
add 20 cents worth of parts to adjust the clock frequency, add $4000
worth of capital equipment to each production station, a week of
additional production line time to setup and program the equipment,
30 seconds of operator time to each board test and decrease the overall
yield.

It really is all about the Benjamins.

Let me restate it in technical terms. You get what you pay for, if
you're lucky.

And yes, my motherboard keeps very good time (but still not anywhere
near as good as my wris****ch). It's not because the design is
different from any other motherboard design. It's because all the
variables conspired to keep good time. I got lucky.

Benjamins!!!

mike

--
Wanted, Serial cable for Dell Axim X5 PDA.
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
htremovethistp://www.geocities.com/SiliconValley/Monitor/4710/

wrote in message
ups.com...
Date: 26 Oct 2005 15:03:04 -0700

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

Not one single person has mentioned that their computer keeps great
time. My first personal computer was back in '81 and it didn't even
sport a clock. Today I have collected about 16 computers (most of them
are in the closet). But the majority of them keeps very good time. Some
haven't been fired up in years, and it is really rare to find one off
more than 5 minutes. So I am at least one user who has been quite
happy with my computer clocks.

______________________________________________
Bill (using a Toshiba 2595XDVD & Windows 2000)
-- written and edited within Word 2000

Hi!

I've often wondered the same thing...also why a $9 alarm clock will have
provision for battery backup, but $200 VCR (back when VCRs were $200)
needed to be rweset with each blip in the mains voltage.

Hmmm...not all of them do. I've got a Panasonic VCR that will hold the
time for a couple of hours after a power failure and a Sony that seems
to be good for a few days. (Of course, both are 'mid-range' machines
and the Sony might qualify as lower high end equipment.)

I also have a Panasonic time-lapse VCR that has a NiCad battery in it.
I know it will the clock for at least two weeks. The manual says it
could last for a month.

William

Hi!

Is that a DS1387 or something else?

I've got some microchannel-based computers that use that module. None
have died yet but I know it is a matter of time.

How did you get the module open? Do you have pictures?

William

In article ,
says...
FWIW, there are utilities which will update your computer clock from the
National Bureau of Standards over the web.....

They call themselves NIST these days, and they also still have
a dialup service.

Hi!

I've always wondered why the batteries in macs run down so quickly. I
rarely see a PC newer than 10 years old with a bad battery, but I
consistently see 3-5 year old macs with totally dead clock batteries.

Yep, I've seen the same thing here. I have a number of old Macs (6100,
6300, LC, 9600, SE/30) that still keep decent time on the
factory-installed batteries. Some of these have gotten to the point
where the machines need to be powered up somewhat often to keep the
settings intact.

By compare I have many a G3 CRT-type iMac around (the 2001 models,
350~500MHz) and almost all of them have had to have their batteries
replaced.

Looking at things I can see one difference. Most PCs new and old power
their CMOS RAM chips from the power supply when they're running. A
great many ATX systems seem to keep the CMOS RAM and clock running from
the ATX standby supply as long as it is running. Some older PCs also
have NiCad or NiMH batteries onboard along with the circuitry to charge
them when powered up.

I've investigated the Macintosh a little bit and it looks like the
clock/NVRAM battery is constantly pulled upon, even when the computer
is on. This could also shorten battery life.

William

Hi!

Not one single person has mentioned that their computer keeps great
time.

Okay then, I'll jump in here. I was just waiting for someone to say it.
:-)

I am a collector and operator of the IBM PS/2 line of computers. I have
a lot of them and most are powered up and running fairly often. Some
run 24/7 as servers.

The clocks on these things are--for the most part--extremely accurate.
I synchronize the clocks on my computers by way of the 'net to one of
the many network time protocol servers in the world. The
synchronization happens at least once a week, sometimes more often. I
don't think I've ever seen one drift more than a second or three
between synchronizations. Of course, it does depend upon the health of
the clock battery. Most people never changed them during the lives of
these computers...so they still run, but are rather weak. I usually
replace them immediately just to avoid a leaking episode.

You can also use these computers as rather large and heavy digital
clocks--they have a flourescent display panel near the power switch
that is normally used for power on self test codes. Fortunately, it is
is user/software-addressable and can be misused in a variety of fun
ways.

http://www.walshcomptech.com/ps2/images/server95big.jpg

The only bad thing about these is that these PS/2s make the clocks in
almost all of my other machines look like a sad joke. :-)

William

In article .com, wrote:
Hi!

I've often wondered the same thing...also why a $9 alarm clock will have
provision for battery backup, but $200 VCR (back when VCRs were $200)
needed to be rweset with each blip in the mains voltage.

Hmmm...not all of them do. I've got a Panasonic VCR that will hold the
time for a couple of hours after a power failure and a Sony that seems
to be good for a few days. (Of course, both are 'mid-range' machines
and the Sony might qualify as lower high end equipment.)

I also have a Panasonic time-lapse VCR that has a NiCad battery in it.
I know it will the clock for at least two weeks. The manual says it
could last for a month.

William


I wanted to add, my alarm clock has a nicad battery backup, which
is why I bought it. Changing batteries is rediculous and expensive.
Why take the time and expense of changing batteries when a built
in nicad is all you need. I have also seen various VCR's that seem
to hold time for a certain period.

greg

In article . com, wrote:
Hi!

Not one single person has mentioned that their computer keeps great
time.

Okay then, I'll jump in here. I was just waiting for someone to say it.
:-)

I am a collector and operator of the IBM PS/2 line of computers. I have
a lot of them and most are powered up and running fairly often. Some
run 24/7 as servers.

The clocks on these things are--for the most part--extremely accurate.
I synchronize the clocks on my computers by way of the 'net to one of
the many network time protocol servers in the world. The
synchronization happens at least once a week, sometimes more often. I
don't think I've ever seen one drift more than a second or three
between synchronizations. Of course, it does depend upon the health of
the clock battery. Most people never changed them during the lives of
these computers...so they still run, but are rather weak. I usually
replace them immediately just to avoid a leaking episode.

You can also use these computers as rather large and heavy digital
clocks--they have a flourescent display panel near the power switch
that is normally used for power on self test codes. Fortunately, it is
is user/software-addressable and can be misused in a variety of fun
ways.

http://www.walshcomptech.com/ps2/images/server95big.jpg

The only bad thing about these is that these PS/2s make the clocks in
almost all of my other machines look like a sad joke. :-)

William

I have seem many computers loose time, and a low battery seems
to increase the loss. An online computer can also be reset. There are programs which
sync to Universal Time, and networks, and even mail programs can
perform syncronization automatically.

greg

Making a accurate oscillator requires two key things
1. An accurate crystal (note stability is not the same as accuracy)
2. An oscillator circuit design that does not "pull" or otherwise change the
basic frequency of the crystal.

Clearly if you design a watch these are primary concerns, so even a cheap
watch is done well

For a computer this not a primary concern and I am sure there is a wide
range of accuracy in different models of computers depending on the amount
of attention paid to these issues. My current computer with an intel mother
board does keep could time.

Dan

--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606

www.QuickScoreRace.com
wrote in message
ups.com...
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

Don Bruder ) writes:

I'm not absolutely certain on that myself, though many explanations have
been put forth over the years, with the one I think is probably "the
real situation" being that Macs (A) Don't cut the battery out of the
circuit when powered up and (B) the battery isn't just keeping the RTC
running, but also keeping a chunk of memory (which we call "PRAM" here
in Mac-land - holds various fairly-to-really critical information) alive.


That second means nothing in itself. "IBM PC" type computers have a tiny
bit of static RAM to hold the bios settings. If it wasn't there, and kept
alive, you'd always have to set those things every time you turn the computer
on.

Now, it may be that one uses more current than the other, but I can't
really see that being a significant difference.

Michael

On Thu, 27 Oct 2005 13:23:26 GMT, "BillW50" wrote:

Not one single person has mentioned that their computer keeps great
time. My first personal computer was back in '81 and it didn't even
sport a clock. Today I have collected about 16 computers (most of them
are in the closet). But the majority of them keeps very good time. Some
haven't been fired up in years, and it is really rare to find one off
more than 5 minutes. So I am at least one user who has been quite
happy with my computer clocks.

There are probably more PC with good clocks than cheap inaccurate
clocks. The reason we rarely saw such posts are because people
usually complain loudly if their product is a bit "off" for any reason
and not many post positive comment on their product.

If everyone were to post every reviews, the bad one would get buried
in a hurry.
--
When you hear the toilet flush, and hear the words "uh oh", it's already
too late. - by anonymous Mother in Austin, TX
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