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Why aren't computer clocks as accurate as cheap quartz watches?
w_tom wrote: 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. |
Why aren't computer clocks as accurate as cheap quartz watches?
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: 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. ... |
Why aren't computer clocks as accurate as cheap quartz watches?
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. 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! |
Why aren't computer clocks as accurate as cheap quartz watches?
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! |
Why aren't computer clocks as accurate as cheap quartz watches?
Who the hell made you the NG God who should say who should and who should
not post a reply. In short, **** 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 bull****. 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" wrote in message ... 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! |
Why aren't computer clocks as accurate as cheap quartz watches?
"w_tom" wrote in message ... 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! What Happens and Why There is a "CMOS clock" in your computer which is powered by a tiny battery. As long as the battery is good, this clock keeps the correct time, and each time your computer is restarted, Windows98 reads its initial time from the CMOS clock. However, while Windows98 is running, it keeps track of the time on its own without continuing to check the CMOS clock, and keeping track of the time is not the only thing Windows has to do. The busier your system gets, the more likely it is to lose time. Generally, the longer you use your computer, the further behind it gets. When you leave your computer on for an extended amount of time, the Windows clock (displayed on the taskbar) may lose from two minutes to an hour per day. Likely culprits Anything that makes your computer especially "busy" can take Windows' attention away from its time-keeping function and lead to this "losing time" symptom. If you're running lots of programs, or even just one or two very demanding programs, you may see the computer clock losing time. Furthermore, anything you are running which causes the computer to have to spend time "watching" for something to happen can also lead to a slow clock. Here are the most common culprits: a.. Games and other video-intensive programs b.. Screen savers and "scheduling" programs c.. Internet chat programs (ICQ, IM, etc.) d.. Playing MP3 files, CDs, or internet audio e.. Anti-virus programs f.. Processor-intensive applications |
Why aren't computer clocks as accurate as cheap quartz watches?
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 $1 ones? See that word "might" ? That word "might" means the poster does not know the answer and therefore should not have posted. Anyone can speculate. But even worse, he posted without reading the answer that was already posted. He did not read every previous post before replying. A program called D4 is equivalent to telling us when that mountain will fall - not relevant to the OP's question. Most replies were just as useless as this one. Why? How can so many post when they never bothered to first learn how a computer's battery powered clock even works? Why is speculation useless? Nobody can give one solid answer because the problem is not identical across all computers, nor is it always caused by one simple factor. I've learned a fair amount of interesting things from this thread, I guess you missed all that. |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
Right on James!
That is how the NG's are suposed to work. But you get these trolls who think there answer is the only answer. They have closed minds. "James Sweet" wrote in message news:t3a8f.3399$I65.1105@trnddc01... 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. |
Why aren't computer clocks as accurate as cheap quartz watches?
"w_tom" wrote in message ... 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. 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 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! |
Why aren't computer clocks as accurate as cheap quartz watches?
Just in case anybody is interested
http://www.thinkman.com/dimension4/index.htm And for the record, Tom, is relevant to the OP's question because it concerns your PC's clock keeping accurate time. It is a solution to the problem. What have you to offer? "w_tom" wrote in message ... 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! |
Why aren't computer clocks as accurate as cheap quartz watches?
"DBLEXPOSURE" wrote in message ...
Just in case anybody is interested http://www.thinkman.com/dimension4/index.htm And for the record, Tom, is relevant to the OP's question because it concerns your PC's clock keeping accurate time. It is a solution to the problem. That wasn't the question. The OP didn't ask how to solve the problem. |
Why aren't computer clocks as accurate as cheap quartz watches?
"Rick Yerger" wrote in message ink.net... "DBLEXPOSURE" wrote in message ... Just in case anybody is interested http://www.thinkman.com/dimension4/index.htm And for the record, Tom, is relevant to the OP's question because it concerns your PC's clock keeping accurate time. It is a solution to the problem. That wasn't the question. The OP didn't ask how to solve the problem. So what? I had offered an answer to that as well as offering a solution. Perhaps you didn't read that part of the thread. Now, Had I said your pc's clock will run slow because magic trolls and ferries sneak in make adjustments to the master oscillator. That might warrant an attack. But the rest of this crap is just that, crap! you see my mind is not one dimensional, I might take a question and expound on the answer to not only give a reason why this happen but also offer a way to correct it. And by the way, my last comment was prefaced, "Just in case anybody is interested". Obviously you are not so the post was not intended for you. In other words, Bug Off, pedal on and get a life! |
Why aren't computer clocks as accurate as cheap quartz watches?
Your other post is classic of those who use emotion as if
emotion was logic. I will pretend you did not post an outburst in the other post; in respect for your dignity. Below is a partial description of how the computer's other clock works. It assumes time lost will also cause the computer's battery clock to change. Do you know they both use completely different circuits and oscillators (time bases)? That battery clock does not change no matter how many seconds or days the Windows (Operating System) clock changes. This might be true if the system is not pre-emptive multitasking or if the OS itself crashes - which is rare enough to not be relevant: The busier your system gets, the more likely it is to lose time. Generally, the longer you use your computer, the further behind it gets. When you leave your computer on for an extended amount of time, the Windows clock (displayed on the taskbar) may lose from two minutes to an hour per day. Meanwhile, as an OS gains or loses time, the computer's battery clock remains unaffected. Again, you should have known this which is why your original post used the word "might". Well, at least this time you look up some facts before posting. But you did not obtain all facts. Loss of time by the OS does not change the CMOS or battery clock. Made obvious with simple hardware or BIOS knowledge. You are advised to first learn the basic circuit - as it was designed even in the original IBM AT. The circuit is based in a famous IC - Motorola's MC146818 and an equivalent IC from Dallas Semiconductor. Not knowing how this battery clock works is not what you are criticized for. Furthermore an emotional outburst was not posted - a lesson you should learn from. Criticism is based on facts. You posted speculation AND you posted things totally irrelevant to what the OP was asking. Not just you. This thread is chock full of posters who only speculated and who did not answer the OP's question. Now you are also being corrected for not learning all the facts about how the battery backup data time clock works. Your "Likely culprits" list is not based on knowledge of a 1984 legacy circuit that is standard in PCs. Gain or loss of time by the OS - using a completely different clock - does not affect the battery backup clock. This true in hardware today as it was in the original IBM AT. Those "most common culprits" in no way change the date time of a battery backup clock. What was do_not_spam_me asking? He was asking about that battery backup clock also known as the CMOS date time chip - which is unaffected by and unrelated to your "most common culprits". IOW again, the answer is not based upon the OP's original question. DBLEXPOSURE wrote: What Happens and Why There is a "CMOS clock" in your computer which is powered by a tiny battery. As long as the battery is good, this clock keeps the correct time, and each time your computer is restarted, Windows98 reads its initial time from the CMOS clock. However, while Windows98 is running, it keeps track of the time on its own without continuing to check the CMOS clock, and keeping track of the time is not the only thing Windows has to do. The busier your system gets, the more likely it is to lose time. Generally, the longer you use your computer, the further behind it gets. When you leave your computer on for an extended amount of time, the Windows clock (displayed on the taskbar) may lose from two minutes to an hour per day. Likely culprits Anything that makes your computer especially "busy" can take Windows' attention away from its time-keeping function and lead to this "losing time" symptom. If you're running lots of programs, or even just one or two very demanding programs, you may see the computer clock losing time. Furthermore, anything you are running which causes the computer to have to spend time "watching" for something to happen can also lead to a slow clock. Here are the most common culprits: a.. Games and other video-intensive programs b.. Screen savers and "scheduling" programs c.. Internet chat programs (ICQ, IM, etc.) d.. Playing MP3 files, CDs, or internet audio e.. Anti-virus programs f.. Processor-intensive applications |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
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. :-) Could you have a look into how these clock are constructed.. ? |
Why aren't computer clocks as accurate as cheap quartz watches?
The battery backup circuit in a PC is a circuit originally
in IBM AT - a legacy of that well established 1984 design using a Motorola MC146818. To have posted as DBLEXPOSURE has, he should have first known about that circuit. A majority of posts in this thread are total speculation based upon no relevant technical knowledge. That is shameful if not irresponsible. One even claims the OS clock causes changes in a completely different oscillator - the CMOS date time clock. Again, one who did not first learn basic facts. Unfortunately too many people (often who are only programmers) somehow become experts on how hardware works. Had he even learned a PC's BIOS, then this would have been obvious. DBLEXPOSURE demonstrates that many just know; cannot bother to first learn how hardware works. It is the difference between one who is product oriented (deals in reality) and the antonym of a product person - the MBA. DBLEXPOSURE posted wild speculation - even worse doing so without first reading a previously posted and technical answer. Two problems in his response are cited. But then he adds a third problem: learns only half of how a CMOS date time clock works; speculates that timing changes in the OS changes a date time clock. First what he (and others) originally posted in response to do_not_spam_me's original question has nothing to do with the question asked by do_not_spam_me. Second, many of those posts all but admit they don't know - based in wild speculation. At least, in a later post, DBLEXPOSURE attempts to learn how the CMOS date time clock works. But he still got it wrong. Those applications - "Likely culprits" - will not affect the battery backup CMOS date time clock. He should have known that even from facts that an inquisitive user observes. BTW, Rick Yerger also criticizes DBLEXPOSURE for not answering the question. Rather than act product oriented, DBLEXPOSURE replies as an MBA: Bug Off, pedal on and get a life! Again he demonstrates no grasp of facts - instead using feelings as if his feelings were facts. I don't have anything to apologize for when I criticize what DBLEXPOSURE and others have posted. Wild speculation was misrepresented as fact - and did not even answer do_not_spam_me's question. Two factors cause significant variation of the CMOS date time clock. No trimmer capacitor and a timer that varies due to different voltages. James Sweet wrote: 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. |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
If there was an answer in this thread, I must have missed it. So many
ideas, so few applications of the facts :-) There are two clocks in a PC (I don't know MACs) A hardware one, and the software clock. When the PC boots, the BIOS reads the hardware clock, and the OS asks the BIOS what time it is. From there on, good old windows or whatever is doing the clock counting, using an interrupt timer. Given the sloppy programming, and the inability of windows to pre-emptively multitask, the software clock is not going to be very accurate. Just open your time settings screen and watch the second hand on the clock. That will show you right away that not only is windows terribly inefficient, it is unable to update the clock consistently, and accurately, even when it is 'idling,' due to system overhead, poorly implemented. Each time you power down or restart the PC, the hardware clock is read, and it is more accurate than the software, although still subject to crappy crystals and poorly implemented devices. If you leave the computer on for days at a time, a restart will probably get the clock back to a more accurate setting, but not necessarily much better. The question of why the PC clock is so inaccurate, and yet more expensive than a cheapo watch is simply a matter of "how ya gonna get the information out of the cheap watch, and into the PC?" The clock itself, and the crystal are only a portion of the hardware required by a PC to know what time it is. The additional requirements increase the sicon die size, as well as the complexity of the design, so the higher cost is to be expected. If you can get the time out of a cheap watch, in binary form, at the proper levels, and the proper timing specs, without raising the price of the $1 watch, a lot of people would like to hear from you ;-) There are many sources of RTC boards that plug into a PCI slot and take over the timekeeping for highly accurate applications, and of course, as so many pointed out, apps the use the National Standards are free and easy given net access. Just another 3.5 cents. Mark |
Why aren't computer clocks as accurate as cheap quartz watches?
lid wrote:
In sci.electronics.basics 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. The answers I found useful in the thread a * Use internal capacitor to adjust for the crystal. * Provide stable voltage. * DS1387 (suns?) have a good track record. * Crystal chassi shall be grounded. Useing these facts it should be possible to construct a fairly precise clock. A precise crystal with internal capacitor in shielded box powered by it's own linear voltage regulator should do it? It could then countup a synchronous counter on positive flank. And be read on negative flank (and only then). Regulator could use diodes to enable proper batteri/psu operation. Separate regulator for counter and crystal. Sure its possible to make an 'accurate' hardware clock, and plenty exist, but there isn't a compelling reason to be obsessive about it for a 'typical' PC as it is either of little consequence (like a standalone PC) or there is a more convenient solution such as domain/internet time synchronization. And domain time synchronization would be needed even if every PC in the domain had an 'accurate' (however we define that) clock because there are too many ways even an 'accurate' clock can get off time, not the least of which being that 'time', when running, is different than the CMOS clock. Its really more complex than just the CMOS clock as that clock isn't what a PC really needs. A computer needs a regular interrupt to schedule tasks and do other time keeping functions so you end up with the situation where the 'software' time doesn't match the 'hardware' time, regardless of how 'accurate' the CMOS clock is, and contrary to w_tom's global assertion that the software time doesn't affect the CMOS clock it depends on the O.S.. Modern Linux systems (e.g. Debian 2.2 and up), for example, set the CMOS clock to the software clock at shutdown so they're synchronized. At any rate, you'd end up going through the pain of trying to make a blisteringly accurate CMOS clock simply so it's blazingly accurate at post rather than waiting a minute for it to synchronize after boot and network access comes up. Is that worth it? |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
D
and the inability of windows to pre-emptively multitask, Incorrect. snip How about offering some insight rather than just a big buzzer? Depends on the version really, Win 3.1 and earlier didn't offer pre-emptive multitasking, when an application was minimized it generally ground to a halt. Win 9x was a big improvement over this but still mediocre. Win NT/2K/XP is better still, and are generally quite good OS's, but the multitasking is still rather poor compared to several other OS's on the market. Of course any OS is a compromise, what you gain in one area you often lose in another. |
Why aren't computer clocks as accurate as cheap quartz watches?
A long time ago, I regularly had good luck by substituting crystals
taken from watches, but when I tried the crystals from computer clocks in some of those watches, their accuracy would worsen considerably. And crystals I bought from parts suppliers were so bad that I switched to getting my crystals from stick-on clocks for cars A National Semiconductor note for one of their clock chips mentioned that common crystals varied from 1-100 ppm accuracy per year (~30 secs. to almost 1 hour), the worst by far being those sealed with solder, the best sealed in glass or without heat. |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
jakdedert writes:
FWIW, there are utilities which will update your computer clock from the National Bureau of Standards over the web..... There's much more than that. There's NTP, which will keep your system clock accurate to within milliseconds without too much trouble. You can also get radio-controlled hardware clocks for installation inside the machine, as well as GPS clocks for even better accuracy. Radio-controlled clocks and NTP over broadband are grossly comparable, but GPS is more accurate still. All of these are far more accurate than the basic clock in the PC alone, which is often off by seconds per day. -- Transpose mxsmanic and gmail to reach me by e-mail. |
Why aren't computer clocks as accurate as cheap quartz watches?
The truth is, I could care less about what you think about what I say. You
are in no position to tell me what I should or what I should not do or have done. If you where a man worth listening to, you would simply post your opinion with no need to tell others how they should or should not have written there post. Truth is, you get off on taking jabs at other rather than simply posting what you think, (typical of a NG twit who cannot be aggressive in the real world for fear of getting bones crushed) Oh, and by the way, What you think it not, nessiccarily the only opinion that counts or matters. So, like I said before, **** you! And I'll post answers in what ever fashion I wish and I will be the judge whether what I post is relevant to the conversation. I don't need you to tell me that either. Who the **** do you really think you are? Cause you aint **** to me.... And by the way, your little game of taking bits and pieces of previous threads is as annoying as the five second sound bite that removes the true context of the conversation and twists the words to suit your own purpose. It is quite transparent as we can all go back and read the thread as it was originally posted. Idiot. Truth of the matter is that the program, "D4" is relevant to this conversation as somebody else may come along and read this thread who never knew the situation could be correct with a small transparent bit of software. That person may appreciate the fact that I brought that subject to the table. Oh, and By the way, the OP might as too. You see, the world doesn't revolve around you and what you think.. Oh, and here is my complete response to Rick Yeager sinip So what? I had offered an answer to that as well as offering a solution. Perhaps you didn't read that part of the thread. Now, Had I said your pc's clock will run slow because magic trolls and ferries sneak in make adjustments to the master oscillator. That might warrant an attack. But the rest of this crap is just that, crap! you see my mind is not one dimensional, I might take a question and expound on the answer to not only give a reason why this happen but also offer a way to correct it. And by the way, my last comment was prefaced, "Just in case anybody is interested". Obviously you are not so the post was not intended for you. In other words, Bug Off, pedal on and get a life! /snip You took 8 word out 4 paragraphs... Who do you really think you are? I'll ask you again to kindly **** off....... "w_tom" wrote in message ... The battery backup circuit in a PC is a circuit originally in IBM AT - a legacy of that well established 1984 design using a Motorola MC146818. To have posted as DBLEXPOSURE has, he should have first known about that circuit. A majority of posts in this thread are total speculation based upon no relevant technical knowledge. That is shameful if not irresponsible. One even claims the OS clock causes changes in a completely different oscillator - the CMOS date time clock. Again, one who did not first learn basic facts. Unfortunately too many people (often who are only programmers) somehow become experts on how hardware works. Had he even learned a PC's BIOS, then this would have been obvious. DBLEXPOSURE demonstrates that many just know; cannot bother to first learn how hardware works. It is the difference between one who is product oriented (deals in reality) and the antonym of a product person - the MBA. DBLEXPOSURE posted wild speculation - even worse doing so without first reading a previously posted and technical answer. Two problems in his response are cited. But then he adds a third problem: learns only half of how a CMOS date time clock works; speculates that timing changes in the OS changes a date time clock. First what he (and others) originally posted in response to do_not_spam_me's original question has nothing to do with the question asked by do_not_spam_me. Second, many of those posts all but admit they don't know - based in wild speculation. At least, in a later post, DBLEXPOSURE attempts to learn how the CMOS date time clock works. But he still got it wrong. Those applications - "Likely culprits" - will not affect the battery backup CMOS date time clock. He should have known that even from facts that an inquisitive user observes. BTW, Rick Yerger also criticizes DBLEXPOSURE for not answering the question. Rather than act product oriented, DBLEXPOSURE replies as an MBA: Bug Off, pedal on and get a life! Again he demonstrates no grasp of facts - instead using feelings as if his feelings were facts. I don't have anything to apologize for when I criticize what DBLEXPOSURE and others have posted. Wild speculation was misrepresented as fact - and did not even answer do_not_spam_me's question. Two factors cause significant variation of the CMOS date time clock. No trimmer capacitor and a timer that varies due to different voltages. James Sweet wrote: 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. |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
James Sweet writes:
How about offering some insight rather than just a big buzzer? Sixteen-bit versions of Windows never did preemptive multitasking. Thirty-two bit versions did and do, for 32-bit applications (but not for 16-bit applications). Windows NT does it for all applications, although a single MS-DOS virtual machine counts as one application (so multiple 16-bit apps running inside it are not preemptively tasked among themselves, for compatibility). Depends on the version really, Win 3.1 and earlier didn't offer pre-emptive multitasking, when an application was minimized it generally ground to a halt. It would not grind to a halt if the current application relinquished control properly and frequently. However, all applications in the system had to be well behaved in this way, or things would stall. Win 9x was a big improvement over this but still mediocre. It only did it for 32-bit applications, and overall Windows 9x was very poorly written. Win NT/2K/XP is better still, and are generally quite good OS's, but the multitasking is still rather poor compared to several other OS's on the market. Not true. Multitasking on all the NT-based versions of Windows is excellent. On those rare occasions when one application stalls another on an NT-based OS, it's not because of any defect in multitasking, it's because of interprocess signalling that stalls applications by (potentially poor) design. For example, the Windows Explorer is a potential source of multiple-application stalls, although the latest versions of Windows Explorer are far better behaved than the original (which was lifted from Windows 95, and was thus very poorly written). Of course, systems such as UNIX have been successfully multitasking since the beginning, given that they were originally timesharing systems by design. -- Transpose mxsmanic and gmail to reach me by e-mail. |
Why aren't computer clocks as accurate as cheap quartz watches?
Michael A. Terrell writes:
Watches have a trimmer to adjust the frequency, but PC motherboards don't, anymore. Some 286 and 386 motherboards had them, and could be set to give fairly accurate time. I don't really care. I use software that updates the clock from time to time and sets it to a few milliseconds from the atomic clocks at NIST. Even if you have a very accurate clock, you still need to synchronize it with NTP or some similar utility if you are using the Internet. Once you start communicating with other machines, it's vital that all the machines be synchronized with respect to time of day--just having a clock that accurately measures time isn't enough. So if you're on a network, either you must synchronize your machine to the Net with software, or you must have a hardware clock that synchronizes to some external source, such as a GPS or radio-controlled clock. In fact, if your computer is _not_ connected to any other computer, then what you need is a clock that is very stable and accurate in its measurement of time intervals. But if your computer is connected to other computers, this stability and accuracy is far less important than synchronization with the other computers. If you have an isolated PC with a very accurate clock, you can set it by hand, and perhaps it will be within one second of the correct time. However, since the clock is accurate, you can be sure that it will never be _more_ than one second away from the correct time. In other words, the initial error is also the maximum error, and a one-second error is often okay for a stand-alone PC as long as the error never increases. Since the computer is not communicating with anything else, the one-second error is not a problem. If you have a PC connected to other PCs, the most important thing is to have all PCs set to the same time. In theory, it doesn't even matter if they drift, as long as they all stay locked together. So clocks that are fast by a second a day are not a problem, as long as all the clocks are off by the same amount. In the case of multiple connected PCs, then, synchronization with each other takes priority over long term stability with respect to the actual time of day. Finally, if your PC is connected to the Internet, you need synchronization with the "real" time of day, as maintained by atomic clocks around the world. This ensures that your PC will have the same time of day as all the other PCs on the network worldwide (assuming they have accurate clocks). So you need software that synchronizes your PC to the correct time of day. You don't actually need a very accurate clock on the PC, though, because good synchronization software--combined with a good operating system--will continually "discipline" your local clock and ensure that the time of day on your machine precisely matches the actual time of day worldwide. In summary, if you have a PC that is continuously connected to the Internet (broadband, for example), all you need is software that will synchronize the clock regularly (and most operating systems have this now--Windows XP does it automatically). If you have a PC that is isolated and not connected to anything, _then_ you need either an extremely accurate PC clock, or some external reference that you can use to keep the clock on time, such as a radio-controlled clock, a GPS clock ... or your own wris****ch. -- Transpose mxsmanic and gmail to reach me by e-mail. |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
James Sweet wrote:
D and the inability of windows to pre-emptively multitask, Incorrect. snip How about offering some insight rather than just a big buzzer? Wasn't necessary as I doubt anyone in here is running 3.1 or older. Depends on the version really, Win 3.1 and earlier didn't offer pre-emptive multitasking, when an application was minimized it generally ground to a halt. Win 9x was a big improvement over this but still mediocre. Win NT/2K/XP is better still, and are generally quite good OS's, but the multitasking is still rather poor compared Not really but then 'poor' is a subjective term. to several other OS's on the market. Of course any OS is a compromise, what you gain in one area you often lose in another. |
Why aren't computer clocks as accurate as cheap quartz watches?
The question of why the PC clock is so inaccurate, and yet more expensive
than a cheapo watch is simply a matter of "how ya gonna get the information out of the cheap watch, and into the PC?" The clock itself, and the crystal are only a portion of the hardware required by a PC to know what time it is. The additional requirements increase the sicon die size, as well as the complexity of the design, so the higher cost is to be expected. If you can get the time out of a cheap watch, in binary form, at the proper levels, and the proper timing specs, without raising the price of the $1 watch, a lot of people would like to hear from you ;-) Well you don't need to get any data only the timeing reference signal. That can then drive an ordinary RTC chip. Maybe this could give some ideas? http://homepage.ntlworld.com/electri...asiowatch.html A solder connection to the pulsetrain from the 32768 kHz crystal + adjusted capacitor to the mainboard rtc. Or simple IrDa. |
Why aren't computer clocks as accurate as cheap quartz watches?
Sixteen-bit versions of Windows never did preemptive multitasking.
Thirty-two bit versions did and do, for 32-bit applications (but not for 16-bit applications). Windows NT does it for all applications, No, windows NT does not pre-emptively multitask. Win NT/2K/XP is better still, and are generally quite good OS's, but the multitasking is still rather poor compared to several other OS's on the market. This is because it only multitasks, but it is not pre-emptive multitasking. The kernel does not have complete control of each application. Not true. Multitasking on all the NT-based versions of Windows is excellent. It is very good, but it is not pre-emptive. OS/2, for one, uses pre-emptive and it is so far ahead and superior to the way windows works, folks would not believe it. The difference between the two is beyond night and day. The difference will prove to be in your definition. The original definition has been absconded with by microsoft in order to make it appear that their inferior implementation actually meets the requirements, so if it is really important that you 'win' that's okay with me. Mark |
Why aren't computer clocks as accurate as cheap quartz watches?
do_not_spam_me said:
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 an answer to your question, but if this is a problem for you and you have a broadband or frequent dial-up connection, you can synchronise your clock with a time server on the internet using a protocol called ntp. -- http://www.niftybits.ukfsn.org/ remove 'n-u-l-l' to email me. html mail or attachments will go in the spam bin unless notified with [html] or [attachment] in the subject line. |
Why aren't computer clocks as accurate as cheap quartz watches?
Win 16 code on Windows 95 executes "cooperative
multitasking". The application program must volunteer to pass CPU access to the next application. Furthermore Win16 code is non reentrant. Windows 95 could only execute Win32 code using a flag called Win16Mutex so that Win32 code, designed for pre-emptive multitasking environments, would not crash in the 'mostly' Win16 environment of Windows 9x/ME. To run Win16 applications in the preemptive multitasking environment of NT, those Win16 applications would execute under NTVDM. Therefore Win16 applications could execute in a pre-emptive multitasking environment called Windows NT. To be a true multitasking system, all threads must be reentrant. This NT does. To be preemptive multitasking, the OS rather than the application programs must determine which code has CPU resources. This too is done by NT. Neither is done in Windows 9x. Some still confuse this difference between Windows 9x/ME and the Windows NT/2000/XP operating systems. NT, however is not a superior real-time pre-emptive multitasking (MT) system. NT was not designed as an efficient real time OS because response to interrupts can take a millisecond. But this discussion is about preemptive MT. Windows 9x/ME is not pre-emptive multitasking. It is cooperative MT. A legacy of DOS and Win 3.1 upon which it was constructed. NT was built from scratch in the earliest 19990s to use Win32 code (code that is also reentrant) and to be preemptive multitasking. XP being only the latest version of the NT Operating System. Some preemptive multitasking OSes take it to the next level - real-time preemptive multitasking. NT can perform real time operations - just not fast enough - microsecond response - as some high performance systems require. OS/2 did provide preemptive multitasking when Windows 95 could only do cooperative MT. However OS/2 has no useful graphical interface. Therefore OS/2 ended up in embedded applications such as ATMs - where the system must be more reliable - therefore system required a preemptive MT OS. Obviously Windows 9x/ME suffer from that reliability weakness. But NT is preemptive MT and has a graphical interface. NT was Microsoft's answer to OS/2 when IBM and Microsoft finally had a parting of the ways in early 1990s. BTW, the early OS/2 that was first demonstrated by IBM - one task could literally lock out other tasks. Even worse, the IBM people did not even understand what multitasking was as we showed them one application locking out other tasks. When first released, bugs in OS/2 caused its preemptive MT abilities to not perform correctly. A legacy of operating system reliability when complex systems are written in assembly language. And just another reason why OS/2 was not a profitable product for IBM. OS/2 biggest success was taking the embedded computer market away from DOS. wrote: Sixteen-bit versions of Windows never did preemptive multitasking. Thirty-two bit versions did and do, for 32-bit applications (but not for 16-bit applications). Windows NT does it for all applications, No, windows NT does not pre-emptively multitask. Win NT/2K/XP is better still, and are generally quite good OS's, but the multitasking is still rather poor compared to several other OS's on the market. This is because it only multitasks, but it is not pre-emptive multitasking. The kernel does not have complete control of each application. Not true. Multitasking on all the NT-based versions of Windows is excellent. It is very good, but it is not pre-emptive. OS/2, for one, uses pre-emptive and it is so far ahead and superior to the way windows works, folks would not believe it. The difference between the two is beyond night and day. The difference will prove to be in your definition. The original definition has been absconded with by microsoft in order to make it appear that their inferior implementation actually meets the requirements, so if it is really important that you 'win' that's okay with me. Mark |
Why aren't computer clocks as accurate as cheap quartz watches?
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Why aren't computer clocks as accurate as cheap quartz watches?
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