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Franc Zabkar
Guest
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 Posted:
Thu Oct 27, 2005 8:35 am Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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On Wed, 26 Oct 2005 23:25:49 GMT, Don Bruder <dakidd@sonic.net> put
finger to keyboard and composed:
| Quote: | In article <1130364184.236610.90350@g47g2000cwa.googlegroups.com>,
do_not_spam_me@my-deja.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.
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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.os.msdos.misc/msg/f59d4241951f84e5?dmode=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.
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DevilsPGD
Guest
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| Posted:
Thu Oct 27, 2005 8:35 am Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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In message <peg0m15m9a3osvbu8q2gpd4us2ibrp2nbo@4ax.com> Jim Adney
<jadney@vwtype3.org> wrote:
| Quote: | On 26 Oct 2005 15:03:04 -0700 do_not_spam_me@my-deja.com 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.
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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.
| Quote: | 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.
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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? |
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Andy Cuffe
Guest
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| Posted:
Thu Oct 27, 2005 8:35 am Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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On Wed, 26 Oct 2005 23:25:49 GMT, Don Bruder <dakidd@sonic.net> wrote:
| Quote: |
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
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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
baltimora@psu.edu <-- Use this address until 12/31/2005
acuffe@gmail.com <-- Use this address after 12/31/2005
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Guest
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| Posted:
Thu Oct 27, 2005 8:35 am Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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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: Start>Control Panel>Date and Time. My pc keeps time
very well.
Glenn
On 26 Oct 2005 15:03:04 -0700, do_not_spam_me@my-deja.com wrote:
| 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.
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mike
Guest
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| Posted:
Thu Oct 27, 2005 8:35 am Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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do_not_spam_me@my-deja.com wrote:
| Quote: | 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.
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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
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/ |
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Mike Foss
Guest
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| Posted:
Thu Oct 27, 2005 1:38 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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"mike" <spamme0@netscape.net> wrote in message news:43608FD0.8030000@netscape.net...
| Quote: | do_not_spam_me@my-deja.com 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
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You seem to be saying curiosity is a worthless trait.
I bet you're a republican. |
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Don Bruder
Guest
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| Posted:
Thu Oct 27, 2005 2:09 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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In article <d0k0m1h9n5g8e8uoos3q66b54b4a6t3j1h@4ax.com>,
Andy Cuffe <baltimora@psu.edu> wrote:
| Quote: | On Wed, 26 Oct 2005 23:25:49 GMT, Don Bruder <dakidd@sonic.net> 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.
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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.
| Quote: | 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.
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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 - dakidd@sonic.net - 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 |
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mike
Guest
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| Posted:
Thu Oct 27, 2005 2:33 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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Mike Foss wrote:
| Quote: | "mike" <spamme0@netscape.net> wrote in message news:43608FD0.8030000@netscape.net...
do_not_spam_me@my-deja.com 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.
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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...
| Quote: | 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
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/ |
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Mike Foss
Guest
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| Posted:
Thu Oct 27, 2005 2:49 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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"mike" <spamme0@netscape.net> wrote in message news:43609ED5.1040705@netscape.net...
| Quote: | Mike Foss wrote:
"mike" <spamme0@netscape.net> wrote in message news:43608FD0.8030000@netscape.net...
do_not_spam_me@my-deja.com 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.
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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. |
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Ken
Guest
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| Posted:
Thu Oct 27, 2005 4:26 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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On Wed, 26 Oct 2005 18:51:12 -0400, Impmon <impmon@digi.mon> wrote:
| 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.
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.
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http://www.tucows.com/downloads/Windows/Internet/TimeSynchronizers/ |
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mike
Guest
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| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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Mike Foss wrote:
| Quote: | "mike" <spamme0@netscape.net> wrote in message news:43609ED5.1040705@netscape.net...
Mike Foss wrote:
"mike" <spamme0@netscape.net> wrote in message news:43608FD0.8030000@netscape.net...
do_not_spam_me@my-deja.com 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 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.
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 wristwatch). 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
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/ |
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BillW50
Guest
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| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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<do_not_spam_me@my-deja.com> wrote in message
news:1130364184.236610.90350@g47g2000cwa.googlegroups.com...
Date: 26 Oct 2005 15:03:04 -0700
| 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.
|
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 |
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Guest
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| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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Hi!
| Quote: | 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 $200)
needed to be rweset with each blip in the mains voltage.
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Hmmm...not all of them do. I've got a Panasonic VCR that will hold the
time for a couple of hours after a power failure and a Sony that seems
to be good for a few days. (Of course, both are 'mid-range' machines
and the Sony might qualify as lower high end equipment.)
I also have a Panasonic time-lapse VCR that has a NiCad battery in it.
I know it will the clock for at least two weeks. The manual says it
could last for a month.
William |
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Ol' Duffer
Guest
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| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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In article <7zT7f.19409$Pp1.3037@bignews3.bellsouth.net>,
jakdedert@bellsouth.net says...
| Quote: | FWIW, there are utilities which will update your computer clock from the
National Bureau of Standards over the web.....
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They call themselves NIST these days, and they also still have
a dialup service. |
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Guest
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| Posted:
Thu Oct 27, 2005 4:35 pm Post subject:
Re: Why aren't computer clocks as accurate as cheap quartz w |
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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 |
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