I'm in the middle of the same book and just read about this part as well. The thing that confused me is, I was under the impression that the 1202/1201 were a surprise to the controllers. I also read "Go, Flight" by Milt Heflin and Rick Houston, but in their version they attributed the success of the mission to a lone controller recalling the obscure code years back. If my memory is correct, they named John Aaron as this controller. There was no mention of a simulation run that brought these codes to the table. It's really thrown me through a loop because these two books, written by very reliable sources seem to differ on the origin of how these program alarms were learned about. I'll keep looking into it, and I'll even try to look back into Go, Flight to see if I can read over its version of things.

@Francois Lacombe So in the book and the film, HAL kills the crew (except Dave Bowman); in the Apollo mission Hal saves the crew and the mission. Art imitates life... life disregards art... sort of. 😉

@@PercivalBlakeney Have you seen 2010? HAL redeemed himself when Jupiter imploded. :)

@Christopher U.S. Smith I'd forgotten about that, turning Jupiter into the dwarf star "Lucifer" (or at least helping the monoliths get the job done 😎). It's explained a lot better (*explained* full stop) in the book. HAL kills the rest of the crew because he has been instructed to keep the real mission objective secret... i.e. the real possibility of extra terrestrial civilisation(s). When Dave and Frank get close to uncovering that something's wrong, HAL panics (like anyone could do), kills the Junonauts in the Hibernacula, kills Frank replacing the Antenna Alignment Module and it's basically luck that saves Dave Bowman. Essentially HAL had been programmed to keep the mission secret... no one had told him to NOT kill in order to accomplish that goal. Like Dr. Chandra says "HAL was told to lie when he didn't know how to... he was told to lie by people who find it easy to lie" ... or words to that effect. If you've not read the book of 2001, I recommend that you do; there's so much in the film that only becomes clear once you've read the source material. Thanks for letting me show off, you're very understanding. 😊

@@PercivalBlakeney The movie was pretty good, but the book was fantastic. Wright Flyer, USAF (1968-1972).

All these worlds are yours, except Europa. Attempt no landing there. Use them together. Use them in peace.

@Kuntor Kunty Someone beat you to it again, Wankor Wanky, so retract your docking probe. ;-)

*blows open hatch*

@@kellyweingart3692 >>> *_"DON'T BLOW THE HATCH!"_** -- MAROONED [1969]* 😊

That was Apollo 15 and it was Al.

The reason they kept popping was Buzz had the rendezvous program running in case they had to abort but the main computer wasn't designed to track another spacecraft AND a landing zone at the same time

@@dosmastrify You got this info from In the shadow of the moon documentary? I don't think this was Buzz choice, it was written on a checklist.

So that's what was buzzing on the screen...

It wasn't exactly preemptive. The main part was cooperative multitaksing with a part - called the "waitlist" which took care of interrupts. The usual thing a waitlist job did was either to change the value directly or to schedule a an ordinary task to take care of that event. For those who don't know the difference preemptive - cooperative: preemptive means, that the operating system can take away the processor at any given time from a task and assign it to another task. Usually this is done by having a sort of system clock interrupt which fires in regular intervalls and the task change is done no matter in which state a specific task currently is. cooperative means that the OS doesn't do that, but instead the whole system relies on a cooperative behaviour of all tasks to release the processor as soon as possible. This means that eg. a task is not allowed to actively wait on some event in a loop. Instead it has to give back control to the operating system and continue the next time it runs where it left off. In the AGC this also meant that in some tasks which had to do a lot of computation work, this work had to be split into subsections with a return to the operating system inbetween. A major reason for that was of course that most of the delicate mathematical computations (as eg. required by the guidance equations) where coded in the interpreter language which run much slower then native code. preemptive operating systems have the beauty that the programmer can code a task just as he would do it when his task is the only thing the computer has to do. But this creates some additional problems, since now a task has to take into account that some variables might change unexpectetly while the algorithm runs (because the task might be interrupted at any time and another task might change some values). This goes down to the deepest level, where memory accesses must be guaranteed to be atomic. All in all, in preemptive multitasking there are a lot of possibilities to screw up the whole system and those problems are extremely hard to debug. Those problems are not an issue with cooperative multitasking, since every task is guaranteed to be able to finish computation but of course no task is allowed to be stubborn and must return control to the operating system in time. State machines are a great way to achieve this behaviour.

Imagine a BSOD

lol we are going back. Wait till they get stuck on a update! :)

Imagine rebooting the AGC and then having to wait for Steam to install updates.

@@ShaneSemler Linux!? The kernel has gotten way too heavy. I'd go for a micro-kernel RTOS like QNX or something similar. A micro-kernel is the surest way to certain of every line of code.

@@CarFreeSegnitz And woven into core rope memory to avoid frying fragile silicon chips. ;)

She is definitely (Out of this world) !!!!!

Ladco77 I'd say that could be a user interface issue today. If you should not use both, then make the user interface force you to have one or the other like a toggle switch. But of course, back then, we had some lessons to learn, and stuff was designed in parallel. The UI team might have not known NOT to allow both ON as the software might not have existed when they finalized the UI... The bleeding edge of science!

Cool analysis arstechnica.com/science/2015/07/no-a-checklist-error-did-not-almost-derail-the-first-moon-landing/

@@Bill_Woo Thanks so much, this is such a great link. I do recall an interview with Aldrin in which he said he kept the rendezvous radar on, but phrased as a casual "I thought it would be a good idea to have the rendezvous radar on just in case." I paraphrase, of course, but I think accurately, because it struck me as so significant at the time. Remember thinking he made it sound as if the idea occurred to him, did it as his own decision, wasn't an included item on the checklist - which seemed very odd. That interview may be the source of the erroneous idea a checklist error underlay the problem. Fascinating that throwing a switch at the wrong nanosecond could cause such a problem.

kzfaq.info/get/bejne/sKmqZZyDvLnVmIU.html please explain this...looking for ANSWERS that's all

Why'd you sign your comment dude. Lmao

Make sure dad doesn't spill the beans on the "hoax". Hillary has a **lot** of time on her hands these days...

Humanity at its finest.

Foolishness at its finest

@@nancyelliot8411 Idiot.

I just bought that book in the Johnson Space Center gift shop yesterday.

Actually, time-sharing was already in use by the mainframes of the era. Task prioritization was a real game changer.

Panic is counter-productive.

no clippy you never help!

M T - I think clippy got relegated to cryo tank stirrer on 13.

Clippy was attached to the 223rd copy of the redacted Mueller report.

an update is available at the microsoft store, would you like to download it? a small fee may be applied to your account.

Genius was my main man, poor young me actually thought it would work better than Clippy ;P

If you are interested in "what you always wanted to know about the AGC but didn't know where to get the information from", I can recommend this talk kzfaq.info/get/bejne/rt5nf8mZmrmvhYU.html Discussion of the software starts at 35:28

"I'm sorry Buzz...I'm afraid I can't do that" ;-)

Shortened version of "Halcombe", his middle name. It's an old family name. Goes back about 5 generations (or so). My son and I both have the same middle name.