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Post by twik on Sept 23, 2011 13:50:04 GMT -4
That may be off-topic, but it's a cute picture!
Back on P1K, I love how he calls Reed "blue collar". Because calculating coordinates for the moon landing is kind of like building cars in the assembly line at Ford, I guess.
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Post by abaddon on Sept 23, 2011 16:54:09 GMT -4
That may be off-topic, but it's a cute picture! Back on P1K, I love how he calls Reed "blue collar". Because calculating coordinates for the moon landing is kind of like building cars in the assembly line at Ford, I guess. He is getting repetitive now he has come full circle all the way back to the poop issue. Guess he is trying to dodge the blunders made on coordinate systems. He is becoming tiresome. Starve the troll, say I. |
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Post by Kiwi on Sept 23, 2011 23:28:22 GMT -4
The childish freak really stooped about as low as it's possible to go in a recent post. Petulant 3-year-olds sometimes resort to name-calling when they can't get their way, but that's no reason why adults should. This is a sample and not the entire selection from the one post: Originally Posted by Patrick1000 forums.randi.org/showthread.php?p=7601034#post7601034 |
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Post by gillianren on Sept 24, 2011 3:00:02 GMT -4
The childish freak really stooped about as low as it's possible to go in a recent post. Petulant 3-year-olds sometimes resort to name-calling when they can't get their way, but that's no reason why adults should. Um . . . I agree that several of these go rather beyond the pale. But . . . . |
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Post by laurel on Sept 25, 2011 13:27:51 GMT -4
It looks like there isn't much moderation on that forum.
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Post by Apollo Gnomon on Sept 25, 2011 14:33:35 GMT -4
It depends on the thread. In that thread moderation appears to be mostly complaint based, and nobody bothers to report P1K's posts. Perhaps we're all giving him enough room to really mess up and get smacked with the ban hammer.
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Post by echnaton on Sept 25, 2011 20:00:13 GMT -4
P1K's signal to noise ratio is fairly low but when something does rise above all that noise, it's good for laugh. Or perhaps it falls below the noise to become a negative signal to noise ratio?
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Post by twik on Sept 26, 2011 10:09:34 GMT -4
P1K does puzzle me. He shows signs of being well-educated, and even the awareness that there are original sources to do his own research, which many hoax believers have not yet discovered. Yet he's completely unable to explain his points in comprehensible language, either meandering on for paragraphs of nothingness, or descending into juvenile namecalling. Then, of course, there's his love affair with his own abilities and writing skills. How many times has he referred to Apollo 11 as a "lost bird"? That metaphor definitely needs a rest.
My favorite comment from him so far is his claim that he was hired by the UN to relieve the "terseness" of their prose in various rulings. Because if there's one thing you don't want bureaucratic writing to be, it's short and to the point.
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Post by PhantomWolf on Sept 26, 2011 15:47:11 GMT -4
It looks like there isn't much moderation on that forum. There is, but it's used to enforce attacks against users of the board, not non-users. Unless Buzz is a member a poster can say anything that they like about him, if he became a member and they still carried on that way, they'd be warned. |
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Post by echnaton on Sept 27, 2011 12:02:37 GMT -4
After reading a few more pages of P1K posts I've hit gimbal lock and can thankfully no longer find my way to the the randi forum.
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Post by chew on Sept 27, 2011 12:51:54 GMT -4
A clever insight only exposes more of his ignorance:
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Post by twik on Sept 27, 2011 20:41:25 GMT -4
P1K had to edit his last post on JREF. This is what it says.
I can add nothing further.
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Post by tedward on Sept 28, 2011 2:14:58 GMT -4
Its like a car crash in a time loop.
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Post by JayUtah on Sept 29, 2011 19:46:26 GMT -4
Obviousman wrote a nice summary of the 1201/1202 program alarms. While I wait for my JREF membership to be approved, let me fill in some gaps.
Program alarms are little more than error messages, although the response to them may automatically take any of several forms: business as usual, a soft restart, or a hard restart.
The soft restart is a software routine that resets a few key data structures, stops nonessential tasks, and reloads the real-time tasks from a predetermined, prioritized table. But it leaves alone things like the state vector and the REFSMMAT. A hard reset is equivalent to powering on the computer anew. 120x alarms prescribe a soft reset.
As you recall, there are only 2,000 words of erasable storage in the computer architecture. The operating system breaks that up into small segments, each of which can be allocated to a running program. Some are reserved for the interpreter and allocated separately by it. The 120x errors indicate that no segments of erasable storage are available for some program that asks for one, and the last digit of the 120x indicates whether it is a regular segment or an interpreter-allocated segment that was asked for.
What exhausted them? The real-time tasks. Normally the small real-time tasks started up, scheduled their next invocation, asked for erasable storage, did their deed, released the storage, and exited -- all in very short time. Some like Servicer ran every 2 seconds and completed their work in just a hundredth of a second or so.
But in the case of Apollo 11 the computer was unexpectedly overloaded. So the real-time tasks took more wallclock time to complete than normal. As a result they never got to the part of their program that released the core sets (the little segments of erasable memory) before new real-time tasks started up according to their wallclock schedule and demanded memory.
So new tasks being scheduled by the relentless wallclock tick of the timer interrupts found the erasable memory glutted by tasks delayed in the relative world of multitasking computing. Under a normal workload there was plenty of computing capacity for all the tasks the designers had assigned.
And what was taking up all the computing power? As stated, the rendezvous radar. In certain modes the radar interrupts the computer periodically to tell it new information. The computer stores it in memory were programs that need radar information can get to it. The radar generates information at a fixed rate, governed by a timing signal from the computer that is interpreted by the radar's power supply. The power supply tells the radar's digital interface when to interrupt the computer.
Now the rendezvous radar was considered important, so it has two redundant power supplies, each locked to the computer timing signal. The radar was in SLEW (i.e., manual) mode at this point. In SLEW mode no data was supposed to be sent to the computer, so the synchronization between the power supplies was allowed to "float" and the digital circuit was supposedly disabled. But it turns out that the out-of-phase signals confused the radar's digital circuit and caused it to emit computer interrupt signals. Not only that, the out-of-phase power-supply cycles generated twice as many interrupts as the digital circuit normally should have. As much as 15 percent of the computer's capacity was being eaten up in accepting the overzealous radar information.
Why was the radar on? Because in an abort, they'd have to turn on the radar, wait for it to warm up, and then give it time to lock onto the CSM and produce good range/rate data. Apollo 11 planners thought it would be a good idea to keep the radar on and warmed up in order to reduce the crew's workload in the case of an abort. Normally in the plan, the radar would be turned off. And in that case it wouldn't have been generating interrupts.
Even under this unexpectedly high load from the double rate of radar interrupts, when none at all were expected, the computer was holding its own. But then Aldrin innocently and expectedly punched Verb 16, Noun 68 into the computer. Verb 16 means "monitor on the DSKY" and Noun 68 is a set of descent parameters: range-to-go, time-to-go, and velocity.
Under the hood, V16 activates a real-time task to read the values from the proper noun location -- here a known place in Program 63's erasable memory -- and load them into the DSKY display registers at regular intervals (once per second, if I recall correctly). A very simple routine, but in this case the straw that broke the camel's back. The continuous-display request was just enough to keep other real-time tasks from exiting cleanly and releasing their memory.
Program 63 is, in guidance terms, a workhorse. It has a lot to do. Programs 64 and 66 require less computing power, so after the computer switched descent modes to P64, the overall computing load lessened so that the computer could maintain its normal workload even with the radar interrupts blazing.
When 120x alarms hit and the soft reset occurs, one of the first things that gets eliminated is the real-time display routine from Verb 16. It's not on the "magic" list of required real-time tasks for this flight mode, so Aldrin's display blanks and the computer goes back to a lean-and-mean operation. Only when he re-enters the display routine does he get in the same situation -- "It seems to happen whenever we have a 16-68 up."
In addition, Armstrong several times switched into ATT HOLD mode (i.e., manual flight) which considerably reduces the digital autopilot's workload. So in P64 and P66, with Armstrong occasionally flying manually, the computer was able to keep up with the spurious radar interrupts, and even V16N68.
In later LMs the rendezvous radar was revised to properly cross-strap the power supplies even in SLEW and AUTO TRACK mode, and the CDUs were revised to more reliably inhibit interrupts altogether except in LGC mode.
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Post by Kiwi on Sept 30, 2011 8:01:48 GMT -4
Many thanks for that, Jay. I've only ever seen the most basic explanations for the alarms, such as "The rendezvous radar overloaded the computer," so it's nice to see the detail. I guess a lot of credit is due to the MIT guys who did the programming with such a basic set-up compared to today's home computers with their bloatware. And speaking of MIT, Don Eyles is the only long-haired guy I've seen having anything to do with Apollo at the time. I guess the short-haired guys had to forgive him for that, and I've sometimes wondered if he wore the obligatory pocket-protector. Don can be seen in the NASA movie "Apollo 14: Mission to Fra Mauro" -- HQ 211 -- at about 0:06:24 to 0:06:29. I've done a seven-page typescript of the NASA TV Programme "Computer For Apollo" and anyone is welcome to PM me to have a copy emailed. The programme, on a Spacecraft Films set, "Mission to the Moon," shows the computer being built and has great descriptions of how and why different things were done, such as spinning parts in a centrifuge to 20,000 g's. |
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