| Author |
Message |
Guest
|
 Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
Hi!
| Quote: | 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
|
|
| Back to top |
|
 |
Guest
|
| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
Hi!
| Quote: | 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 |
|
| Back to top |
|
|
GregS
Guest
|
| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
In article <1130423459.185889.273670@f14g2000cwb.googlegroups.com>, wm_walsh@hotmail.com wrote:
| Quote: | 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
|
|
| Back to top |
|
|
Dan Hollands
Guest
|
| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
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
QuickScore@USSailing.net
www.QuickScoreRace.com
<do_not_spam_me@my-deja.com> wrote in message
news:1130364184.236610.90350@g47g2000cwa.googlegroups.com...
| Quote: | 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.
|
|
|
| Back to top |
|
|
Michael Black
Guest
|
| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
Don Bruder (dakidd@sonic.net) writes:
| Quote: | 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 |
|
| Back to top |
|
|
GregS
Guest
|
| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
In article <1130425586.052385.18380@o13g2000cwo.googlegroups.com>, wm_walsh@hotmail.com wrote:
| Quote: | 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 |
|
| Back to top |
|
|
Impmon
Guest
|
| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
On Thu, 27 Oct 2005 13:23:26 GMT, "BillW50" <BillW50@aol.kom> wrote:
| Quote: | 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
To reply, replace digi.mon with phreaker.net |
|
| Back to top |
|
|
Guest
|
| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
w_tom wrote:
| Quote: | 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.
|
I have an ancient Seiko quartz with a trimmer inside, and by adjusting
it I was able to make it accurate to 30 seconds a year. But few cheap
watches have them, including none of those I tried in this test. |
|
| Back to top |
|
|
w_tom
Guest
|
| Posted:
Thu Oct 27, 2005 10:41 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
There are two ways to do as suggested. The first is to make
'Benjamins' part of the technical facts during design. The
second is to do the design, then let bean counters change the
design per what they 'feel' is not worth the bucks. The
latter is too often how GM cars are designed. Which is why a
GM car needs two extra pistons to get the same horsepower as
the competition. Which is why GM cars even in the 1990s
required annual wheel alignment. Which is why GM cars would
have what appeared to be computer failures when failure was
really due to cheap connectors. Classic examples of failures
when the design is modified after the design.
Two examples: how 'Benjamin' decisions become part of a
successful design verses how 'Benjamin' decisions after
application of technical facts makes bankruptcy.
Meanwhile, the technical reason for high verses low accuracy
timers was provided. Computer motherboards don't have the
trimming capacitor and the oscillator is subject to wider
voltage variations. Why this technical decision was made was
not asked and would only be speculation.
mike wrote:
| Quote: | 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 wristwatch 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.
... |
|
|
| Back to top |
|
|
Andy Cuffe
Guest
|
| Posted:
Thu Oct 27, 2005 10:42 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
On 27 Oct 2005 08:06:26 -0700, wm_walsh@hotmail.com wrote:
IBM did a lot of things wrong with their PCs in terms of performance,
upgradability and user friendliness, but their quality was second to
none un until the end of the PS/2 line.
Andy Cuffe
baltimora@psu.edu <-- Use this address until 12/31/2005
acuffe@gmail.com <-- Use this address after 12/31/2005 |
|
| Back to top |
|
|
DBLEXPOSURE
Guest
|
| Posted:
Thu Oct 27, 2005 10:58 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
<do_not_spam_me@my-deja.com> wrote in message
news:1130364184.236610.90350@g47g2000cwa.googlegroups.com...
| Quote: | 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.
|
Because the processor in your computer might hang or busy itself with other
things besides keeping time. It may also have something to do with the
clock pulses your computer uses not being exactly divisible into real time.
look for a program called D4. It is a free download and will keep your
clock synced to universal time. Also, Widows XP can sync to the same time
servers that D4 uses. Both work great! |
|
| Back to top |
|
|
w_tom
Guest
|
| Posted:
Thu Oct 27, 2005 11:16 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
Why so many "it might be this" or "it might be that" or
"time is updated from the internet"? Every posts says nothing
useful AND does not answer the OPs question. OP even
clarified the question when some replies were rubbish.
The answer -- technically -- was posted without
speculation. Processor hangs obviously do not affect that
clock operation - it one first learned how something works
before posting. The OP posted this - a technical question
that required technical knowledge before replying:
| Quote: | Why do the battery powered clocks in personal computers tend
to keep worse time than quartz watches, even the $1 ones?
|
See that word "might" ? That word "might" means the poster
does not know the answer and therefore should not have
posted. Anyone can speculate. But even worse, he posted
without reading the answer that was already posted. He did
not read every previous post before replying. A program
called D4 is equivalent to telling us when that mountain will
fall - not relevant to the OP's question. Most replies were
just as useless as this one. Why? How can so many post when
they never bothered to first learn how a computer's battery
powered clock even works?
DBLEXPOSURE wrote:
| Quote: | Because the processor in your computer might hang or busy itself
with other things besides keeping time. It may also have
something to do with the clock pulses your computer uses not
being exactly divisible into real time.
look for a program called D4. It is a free download and will keep your
clock synced to universal time. Also, Widows XP can sync to the same time
servers that D4 uses. Both work great! |
|
|
| Back to top |
|
|
DBLEXPOSURE
Guest
|
| Posted:
Thu Oct 27, 2005 11:42 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
Who the hell made you the NG God who should say who should and who should
not post a reply. In short, Fuck You!
Don't tell me that the time kept by your computer does not require a
processor and that it does not ever hang because that is bullshit.
The fact that the OP asked the question leads me to assume that his clock on
his computer not keeping accurate time is annoying him. Therefore, I
recommended the Program called D4. It is a solution to the problem and it
works.
"w_tom" <w_tom1@hotmail.com> wrote in message
news:43611992.11734CA9@hotmail.com...
| Quote: | Why so many "it might be this" or "it might be that" or
"time is updated from the internet"? Every posts says nothing
useful AND does not answer the OPs question. OP even
clarified the question when some replies were rubbish.
The answer -- technically -- was posted without
speculation. Processor hangs obviously do not affect that
clock operation - it one first learned how something works
before posting. The OP posted this - a technical question
that required technical knowledge before replying:
Why do the battery powered clocks in personal computers tend
to keep worse time than quartz watches, even the $1 ones?
See that word "might" ? That word "might" means the poster
does not know the answer and therefore should not have
posted. Anyone can speculate. But even worse, he posted
without reading the answer that was already posted. He did
not read every previous post before replying. A program
called D4 is equivalent to telling us when that mountain will
fall - not relevant to the OP's question. Most replies were
just as useless as this one. Why? How can so many post when
they never bothered to first learn how a computer's battery
powered clock even works?
DBLEXPOSURE wrote:
Because the processor in your computer might hang or busy itself
with other things besides keeping time. It may also have
something to do with the clock pulses your computer uses not
being exactly divisible into real time.
look for a program called D4. It is a free download and will keep your
clock synced to universal time. Also, Widows XP can sync to the same
time
servers that D4 uses. Both work great! |
|
|
| Back to top |
|
|
DBLEXPOSURE
Guest
|
| Posted:
Fri Oct 28, 2005 12:35 am Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
Right on James!
That is how the NG's are suposed to work. But you get these trolls who
think there answer is the only answer. They have closed minds.
"James Sweet" <jamessweet@hotmail.com> wrote in message
news:t3a8f.3399$I65.1105@trnddc01...
| Quote: | w_tom wrote:
Why so many "it might be this" or "it might be that" or
"time is updated from the internet"? Every posts says nothing
useful AND does not answer the OPs question. OP even
clarified the question when some replies were rubbish.
The answer -- technically -- was posted without
speculation. Processor hangs obviously do not affect that
clock operation - it one first learned how something works
before posting. The OP posted this - a technical question
that required technical knowledge before replying:
Why do the battery powered clocks in personal computers tend
to keep worse time than quartz watches, even the $1 ones?
See that word "might" ? That word "might" means the poster
does not know the answer and therefore should not have
posted. Anyone can speculate. But even worse, he posted
without reading the answer that was already posted. He did
not read every previous post before replying. A program
called D4 is equivalent to telling us when that mountain will
fall - not relevant to the OP's question. Most replies were
just as useless as this one. Why? How can so many post when
they never bothered to first learn how a computer's battery
powered clock even works?
Why is speculation useless? Nobody can give one solid answer because the
problem is not identical across all computers, nor is it always caused by
one simple factor. I've learned a fair amount of interesting things from
this thread, I guess you missed all that. |
|
|
| Back to top |
|
|
JAD
Guest
|
| Posted:
Fri Oct 28, 2005 12:35 am Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
|
|
"w_tom" <w_tom1@hotmail.com> wrote in message
news:43611992.11734CA9@hotmail.com...
| Quote: | Why so many "it might be this" or "it might be that" or
"time is updated from the internet"? Every posts says nothing
useful AND does not answer the OPs question. OP even
clarified the question when some replies were rubbish.
The answer -- technically -- was posted without
speculation. Processor hangs obviously do not affect that
clock operation - it one first learned how something works
before posting. The OP posted this - a technical question
that required technical knowledge before replying:
|
And your answer was? or were you just posting to post.
| Quote: | Why do the battery powered clocks in personal computers tend
to keep worse time than quartz watches, even the $1 ones?
See that word "might" ? That word "might" means the poster
does not know the answer and therefore should not have
posted. Anyone can speculate.
|
In this environment speculation is just about all you have as the machine
(subject) is rarely in your hands. Since then a phrase has been invented to
take the place of that....and that would be...YMMV
But even worse, he posted
| Quote: | without reading the answer that was already posted. He did
not read every previous post before replying. A program
called D4 is equivalent to telling us when that mountain will
fall - not relevant to the OP's question. Most replies were
just as useless as this one. Why? How can so many post when
they never bothered to first learn how a computer's battery
powered clock even works?
DBLEXPOSURE wrote:
Because the processor in your computer might hang or busy itself
with other things besides keeping time. It may also have
something to do with the clock pulses your computer uses not
being exactly divisible into real time.
look for a program called D4. It is a free download and will keep your
clock synced to universal time. Also, Widows XP can sync to the same
time
servers that D4 uses. Both work great! |
|
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in