Researching the equation of time might be enlightening. I thought the earth rotated on its axis at a constant rate of once in 24 hours. After thinging about it I realized this couldn't be true or noon and midnight would be swapped every 6 months. I concluded that, in 24 hours, the earth rotated so that any given point would again be facing the sun. Again incorrect. The orbit of the earth around the sun isn't circular so its rotational speed changes during the year. This has been known for a long time I think. Do some research on sundials and the strange figure 8 on most of them.
This thread has really run off the rails now.
Sandy
Yes, that called "equation of time". Drift is less than 15 minutes and it's absolutely predictable. So? Is it problem? More important problems is that Moon is slowing down Earth rotation. That is reason why we need leap seconds sometimes. So one of the solutions is to keep time in cesium standard because it is one of the fundamental constants (for beginner hackers: this).
Another discussion: what if speed of light is variable no constant and we can observe it as constant because we are "In The Box". Let's think "Out of Box"... What if...?
There may not be anything intrinsically base 12 about the earths rotation, but the time it takes for one rotation was divided up into base 12 multiples, so the only way to make it fit any other base neatly would be to change the length of the second. Not something to be done lightly since so many of our other units and measurements are based on the length of a second.
Actually it is base 24 not base 12. This AM/PM stuff is just another bit. But a day has 24 hours not 12.
The ancient Babylonians' number system was base 60. (Imagine their BSCII code!) Sixty is a convenient number, since it has so many prime factors (2,2,3,5) and can be subdivided neatly in so many ways. 60, divided by its largest prime factor, 5, is 12. Hence, dozens, twelve-hour demi-days, 12 months in a year, 12 points to a pica (a printer's ruler is divided into 1/12ths of an inch, not 1/16ths), etc. Moreover, 60 seconds to a minute and 60 minutes to an hour (or degree) are all derived from this handy multiplicity of primes. Had we evolved with 12 fingers (or maybe 16 for the digital age?) instead of 10, math would be so much easier!
Researching the equation of time might be enlightening. I thought the earth rotated on its axis at a constant rate of once in 24 hours. After thinging about it I realized this couldn't be true or noon and midnight would be swapped every 6 months. I concluded that, in 24 hours, the earth rotated so that any given point would again be facing the sun. Again incorrect. The orbit of the earth around the sun isn't circular so its rotational speed changes during the year. This has been known for a long time I think. Do some research on sundials and the strange figure 8 on most of them.
This thread has really run off the rails now.
Sandy
Can you please explain why noon and midnight might swap every half year? I can not really see this effect. Please enlighten me there.
As far as I understand the rotational speed of earth around its own axis is not changing at all over the year. Way to much mass involved. Same with the speed of the earth around the sun. Neither going slower nor faster. Keeping their job going. The only thing changing is the distance from the sun and the angle of the sun rays involved since the rotational axis of the planet is sort of angled while rotating around the sun and the rotational axis of the planet is not always in the same angle compared to the position of the sun.
That is the main reason why we have seasons. Good thing to have. Would be boring else.
So we have longer and shorter phases of daylight coming from a different angle over the year. But, well a day still will have 24 hours. Because that is basically the definition of a day. We figured that out quite well over the last 2,000+ years. Every four years we have to throw in another day, every 400(?) we don't, except every 1000(?) years, and every couple of years we have to throw in a second. That is what we have more or less.
But still time does not change and the way the planet earth moves around the sun does not change. At least not noticeable for ourselves.
And, please, do not tell me that our earth wants to do a entry in @erco's figure 8 challenge. If I am wrong, post a entry. I wish I had something running to post there but it is not running yet. Sadly no time to play.
So back to them number systems.
As @PhiPi said so well a base 60 system has its beauty in itself. Not sure about the additional fingers.
I once visited one of my sisters working in Portugal. She is a nurse. So visiting her at her place I went to the local supermarket, and something was wrong with the clerk. I was not able to nail it down. So after the second or third time of me going there I asked her about the guy. She said 'Ahh you are talking about six finger Joe'. Then I got it. The Guy had 5 fingers and a thump. Not 4. She told me that this is not as unusual as I thought of. Something like one out of a thousand newborn have that. Usually it gets removed quite quick. Sometimes the parents object against removing them. Same with toes 6 not 5.
So evolution is trying to get us to a base 12 (or 60) system. But evolution is slow.
Same with the speed of the earth around the sun. Neither going slower nor faster.
No, that speed does change. Because the earth's orbit is elliptical, not circular. The velocity is faster closer to the sun and slower when the earth is farther from the sun. If you draw a line from the earth to the sun at time A and another line from the earth to the sun at a later time B, the area inside the triangle stays the same at all times. So when the earth is closer to the sun it moves with a higher velocity so that the area remains the same. Kepler's laws and all that.
This effect is noticable to us - as the earth is at its closest (and fastest) point to the sun mid-winter on the northern hemisphere, after winter equinox the day starts to get longer (as expected) but the time of sunrise keeps getting later, for some days after equinox. It can't quite keep up.
So we have longer and shorter phases of daylight coming from a different angle over the year. But, well a day still will have 24 hours. Because that is basically the definition of a day. We figured that out quite well over the last 2,000+ years. Every four years we have to throw in another day, every 400(?) we don't, except every 1000(?) years, and every couple of years we have to throw in a second. That is what we have more or less.
Yep, the 24 hour rotation time was pretty much sorted out early. The actual solar day though.. because of the movement around the sun the time from one noon to the next one is shorter, so you'll need to add days now and then. The calendar from Caesar's time introduced a leap year every 4th year. They didn't get it (nearly) right until Gregorian's calendar was introduced 1600 years later or so, when our current system of a leap year every 4th year unless the year is divisible with 100 except when it's also divisible with 400 in which case it *is* a leap year. Further fine-adjustments have not been introduced.
As for leap seconds, they are introduced only irregularly. There are all kinds of reasons for the earth speeding up or slowing down occasionally, including earthquakes, tsunamis, shifting ice from the poles etc. Since 1980 or so there have been 16. There will be another one end of June this hear. The previous one was in 2012, there was one in 2008 and one in 2005, the one before that was in 1998. In the early nineties there was one every year.
But still time does not change and the way the planet earth moves around the sun does not change. At least not noticeable for ourselves.
As mentioned above, it's quite noticable around the northern hemisphere winter equinox, at least if you look.
Actually earth rotation isn't exact number. Its fractional. As result year is 365.25 days long. That is the reason of leap day on February 29. Reason for leap seconds are because earth orbit is 365.256363004 days long. So rounding error regularly acuumulates and... If we add precession, nutation, gravitational effects of Moon etc... There are lot of small things to get precise time. Just look on UTC and IAT relation.
Actually earth rotation isn't exact number. Its fractional. As result year is 365.25 days long. That is the reason of leap day on February 29. Reason for leap seconds are because earth orbit is 365.256363004 days long.[..]
No, that's not entirely correct. Leap seconds are to adjust for other irregularities. If the 0.006363004 days were the main reason for leap seconds then leap seconds adjustments would come pretty regularly. Which is not the case. They can in principle happen every half year (end of June, end of December), but there can be years between adjustments and then suddenly several in a row. To cite wikipedia on leap seconds: "Because the Earth's rotation speed varies in response to climatic and geological events, UTC leap seconds are irregularly spaced and unpredictable."
(and they can be negative too, not just positive. Although they have been only positive since leap seconds were introduced in 1972. And in 1972 they had two of them.. in June and December. And until 1980 there was one every year. But from 1998 to 2005 there were none.)
As for the lenght of the day.. rotation time *is* actually 24 hours, but because the earth moves the *solar time* is 4 minutes less. And that's why you accumulate an error that results in leap days: http://www.gb.nrao.edu/GBTopsdocs/primer/solar_vs._sidereal_day.htm
[Edit: Got that backwards of course - ref. the link]
The solar day is 24 hours. The sidereal day is 4 minutes less. Leap days are required because the earth's orbital period (year) is not an integral multiple of solar days.
The solar day is 24 hours. The sidereal day is 4 minutes less. Leap days are required because the earth's orbital period (year) is not an integral multiple of solar days.
Looks like they have been tested with some image: [/FONT][/COLOR]
@Publison: Yes, I absolutely took note of the word "tested" prior posting. However, I guessed that such testing involved continuity and so forth.
In full disclosure, though, I will admit that, when I first considered posting, I hadn't yet thought about adding the wording about testing with an image. So, it turns out that your assumption about my reading ability is not far off the mark, I'm not proud to say (and not too proud to admit).
I guess you saw through my little attempt to get the thread back on topic. My apologies if my attempt to do so in subtle way offended you. Perhaps it wasn't forthright. I was hoping my post might generate some additional details. You can't blame a guy for trying (Well, you can, but it usually won't stop him). Forgive my impatience, though I did wait a week to post after seeing the informative post with the link.
I will say that merely seeing a batch of boards racked up (next to other boards potentially off production/testing) doesn't immediately scream "Rigorously Tested!" in my thinking. But if they have indeed been tested with an image (even a simple one), then, cool! That would mean that we're one step closer. Hope it's the case...or will be soon.
@Publison: Yes, I absolutely took note of the word "tested" prior posting. However, I guessed that such testing involved continuity and so forth.
In full disclosure, though, I will admit that, when I first considered posting, I hadn't yet thought about adding the wording about testing with an image. So, it turns out that your assumption about my reading ability is not far off the mark, I'm not proud to say (and not too proud to admit).
I guess you saw through my little attempt to get the thread back on topic. My apologies if my attempt to do so in subtle way offended you. Perhaps it wasn't forthright. I was hoping my post might generate some additional details. You can't blame a guy for trying (Well, you can, but it usually won't stop him). Forgive my impatience, though I did wait a week to post after seeing the informative post with the link.
I will say that merely seeing a batch of boards racked up (next to other boards potentially off production/testing) doesn't immediately scream "Rigorously Tested!" in my thinking. But if they have indeed been tested with an image (even a simple one), then, cool! That would mean that we're one step closer. Hope it's the case...or will be soon.
It seems likely that they were tested with a P1v image. Just a guess but it is called a Propeller 1-2-3 FPGA board.
It seems likely that they were tested with a P1v image. Just a guess but it is called a Propeller 1-2-3 FPGA board.
When I saw the name of the board last week, I asked myself what the name signified, if anything. I didn't come up with an answer. And I'm still not clear.
Are you suggesting that the board is named 1-2-3 because it's good for testing variants of the Prop 1, the working design of the Prop 2, and a future design for a Prop 3? If so, that's kind of clever. Might be a bit presumptive, though, in the case of a Prop 3 because, if a Prop 3 is produced, it might be done in smaller semiconductor process. But perhaps the 1-2-3 board could still test out a subset of its functionality (such as maybe a reduced number of cogs). That's pretty forward thinking. I like it! Is that really the reason? Sorry, if it was supposed to be obvious (I'm becoming denser by the day).
Anyway, now that Chip-and-Company have come up to speed with a new set of design tools (and other connections/resources), it's tempting to think that a Prop 3 could be turned around in a fraction of the time of the Prop 1 or 2, maybe in less than three years, particularly if such a design substantially built on the Prop 2, which there's a good chance that it would.
I wasn't being serious. Just extending what you already said to a finished re-engineered Prop1. There's been the desire for the 64 I/O with multiply instruction revisit of the Prop1 for a long time, and I think it's been said the only reason it never happened was it needed re-engineered due to the original tools not working any longer.
Maybe a heavily cut down, extra low power version derived from the current Prop2 design might be being considered. Prop1 binary compatibility would be unlikely though.
I wasn't being serious. Just extending what you already said to a finished re-engineered Prop1. There's been the desire for the 64 I/O with multiply instruction revisit of the Prop1 for a long time, and I think it's been said the only reason it never happened was it needed re-engineered due to the original tools not working any longer.
Maybe a heavily cut down, extra low power version derived from the current Prop2 design might be being considered. Prop1 binary compatibility would be unlikely though.
hehe, just dribbling ...
Yeah, I think that would be an interesting part. But if they ever did that there would be some tweaks that would be made I'm sure. I'd like 64K of hub RAM with a small bootloader and support for booting from SPI flash. Others would want other things. Pretty soon it would become P2++.
Grief yes, I pull up a big mug of tea and settle down to a potatohead essay. What do we get? Three words! And two of them are the same.
This chip had better arrive soon. Or I'll be hanging up my soldering iron for the last time. Shuffling off this mortal inductor, having exhausted my capacity, unable to offer resistance any more. Following the shortest path to ground.
Comments
Yes, that called "equation of time". Drift is less than 15 minutes and it's absolutely predictable. So? Is it problem? More important problems is that Moon is slowing down Earth rotation. That is reason why we need leap seconds sometimes. So one of the solutions is to keep time in cesium standard because it is one of the fundamental constants (for beginner hackers: this).
Another discussion: what if speed of light is variable no constant and we can observe it as constant because we are "In The Box". Let's think "Out of Box"... What if...?
Parallax better get the Prop II out before the earth stops rotating!
Believe me, they (Parallax inc.) will do!
Actually it is base 24 not base 12. This AM/PM stuff is just another bit. But a day has 24 hours not 12.
Seriously.
Mke
-Phil
Can you please explain why noon and midnight might swap every half year? I can not really see this effect. Please enlighten me there.
As far as I understand the rotational speed of earth around its own axis is not changing at all over the year. Way to much mass involved. Same with the speed of the earth around the sun. Neither going slower nor faster. Keeping their job going. The only thing changing is the distance from the sun and the angle of the sun rays involved since the rotational axis of the planet is sort of angled while rotating around the sun and the rotational axis of the planet is not always in the same angle compared to the position of the sun.
That is the main reason why we have seasons. Good thing to have. Would be boring else.
So we have longer and shorter phases of daylight coming from a different angle over the year. But, well a day still will have 24 hours. Because that is basically the definition of a day. We figured that out quite well over the last 2,000+ years. Every four years we have to throw in another day, every 400(?) we don't, except every 1000(?) years, and every couple of years we have to throw in a second. That is what we have more or less.
But still time does not change and the way the planet earth moves around the sun does not change. At least not noticeable for ourselves.
And, please, do not tell me that our earth wants to do a entry in @erco's figure 8 challenge. If I am wrong, post a entry. I wish I had something running to post there but it is not running yet. Sadly no time to play.
So back to them number systems.
As @PhiPi said so well a base 60 system has its beauty in itself. Not sure about the additional fingers.
I once visited one of my sisters working in Portugal. She is a nurse. So visiting her at her place I went to the local supermarket, and something was wrong with the clerk. I was not able to nail it down. So after the second or third time of me going there I asked her about the guy. She said 'Ahh you are talking about six finger Joe'. Then I got it. The Guy had 5 fingers and a thump. Not 4. She told me that this is not as unusual as I thought of. Something like one out of a thousand newborn have that. Usually it gets removed quite quick. Sometimes the parents object against removing them. Same with toes 6 not 5.
So evolution is trying to get us to a base 12 (or 60) system. But evolution is slow.
Enjoy!
Mike
This effect is noticable to us - as the earth is at its closest (and fastest) point to the sun mid-winter on the northern hemisphere, after winter equinox the day starts to get longer (as expected) but the time of sunrise keeps getting later, for some days after equinox. It can't quite keep up.
Yep, the 24 hour rotation time was pretty much sorted out early. The actual solar day though.. because of the movement around the sun the time from one noon to the next one is shorter, so you'll need to add days now and then. The calendar from Caesar's time introduced a leap year every 4th year. They didn't get it (nearly) right until Gregorian's calendar was introduced 1600 years later or so, when our current system of a leap year every 4th year unless the year is divisible with 100 except when it's also divisible with 400 in which case it *is* a leap year. Further fine-adjustments have not been introduced.
As for leap seconds, they are introduced only irregularly. There are all kinds of reasons for the earth speeding up or slowing down occasionally, including earthquakes, tsunamis, shifting ice from the poles etc. Since 1980 or so there have been 16. There will be another one end of June this hear. The previous one was in 2012, there was one in 2008 and one in 2005, the one before that was in 1998. In the early nineties there was one every year.
As mentioned above, it's quite noticable around the northern hemisphere winter equinox, at least if you look.
(and they can be negative too, not just positive. Although they have been only positive since leap seconds were introduced in 1972. And in 1972 they had two of them.. in June and December. And until 1980 there was one every year. But from 1998 to 2005 there were none.)
As for the lenght of the day.. rotation time *is* actually 24 hours, but because the earth moves the *solar time* is 4 minutes less. And that's why you accumulate an error that results in leap days: http://www.gb.nrao.edu/GBTopsdocs/primer/solar_vs._sidereal_day.htm
[Edit: Got that backwards of course - ref. the link]
Picky, picky, but ok, you're right.
Wonder if any of those boards have been tested with any kind of image yet (not necessarily a P2 one), just to verify basic operation.
Looks like they have been tested with some image:
@Publison: Yes, I absolutely took note of the word "tested" prior posting. However, I guessed that such testing involved continuity and so forth.
In full disclosure, though, I will admit that, when I first considered posting, I hadn't yet thought about adding the wording about testing with an image. So, it turns out that your assumption about my reading ability is not far off the mark, I'm not proud to say (and not too proud to admit).
I guess you saw through my little attempt to get the thread back on topic. My apologies if my attempt to do so in subtle way offended you. Perhaps it wasn't forthright. I was hoping my post might generate some additional details. You can't blame a guy for trying (Well, you can, but it usually won't stop him). Forgive my impatience, though I did wait a week to post after seeing the informative post with the link.
I will say that merely seeing a batch of boards racked up (next to other boards potentially off production/testing) doesn't immediately scream "Rigorously Tested!" in my thinking. But if they have indeed been tested with an image (even a simple one), then, cool! That would mean that we're one step closer. Hope it's the case...or will be soon.
Lol, that's observant! A Prop1B is on the way after all ...
When I saw the name of the board last week, I asked myself what the name signified, if anything. I didn't come up with an answer. And I'm still not clear.
Are you suggesting that the board is named 1-2-3 because it's good for testing variants of the Prop 1, the working design of the Prop 2, and a future design for a Prop 3? If so, that's kind of clever. Might be a bit presumptive, though, in the case of a Prop 3 because, if a Prop 3 is produced, it might be done in smaller semiconductor process. But perhaps the 1-2-3 board could still test out a subset of its functionality (such as maybe a reduced number of cogs). That's pretty forward thinking. I like it! Is that really the reason? Sorry, if it was supposed to be obvious (I'm becoming denser by the day).
Anyway, now that Chip-and-Company have come up to speed with a new set of design tools (and other connections/resources), it's tempting to think that a Prop 3 could be turned around in a fraction of the time of the Prop 1 or 2, maybe in less than three years, particularly if such a design substantially built on the Prop 2, which there's a good chance that it would.
I wasn't being serious. Just extending what you already said to a finished re-engineered Prop1. There's been the desire for the 64 I/O with multiply instruction revisit of the Prop1 for a long time, and I think it's been said the only reason it never happened was it needed re-engineered due to the original tools not working any longer.
Maybe a heavily cut down, extra low power version derived from the current Prop2 design might be being considered. Prop1 binary compatibility would be unlikely though.
hehe, just dribbling ...
Go Chip GO!
I'm not sure what is more of a surprise, the lack of news or a three word post from Doug...
;-)
C.W.
This chip had better arrive soon. Or I'll be hanging up my soldering iron for the last time. Shuffling off this mortal inductor, having exhausted my capacity, unable to offer resistance any more. Following the shortest path to ground.
T + 3 days