I was watching Apollo 13 while getting ready for work this morning. The guidance computer is shown several times. It has three, I guess headings. Prog, which I assume is “program”, noun, and verb. What do noun and verb mean in this case?
This is from the link above.
Thanks! I didn’t even think of looking there…
I love that some of the verbs are preceded by “please.” They were very polite to their computers.
Maybe they were afraid a computer would turn against them like HAL did with Dave.
The Apollo guidance computer was one of the most remarkable parts of the whole Apollo program, second only to the design of the turbopumps that fed the F1 engines on the first stage of the Saturn 5. (The entire Apollo program was a project to design a turbopump with “going to the moon” tacked on as an extra).
I love how the computer’s memory was measured in bytes per foot, since it was literally woven onto rope by little old ladies.
Bolding mine
Can you expand on this? I don’t really get it and didn’t see it in the Wikipedia article.
in the article is a link to
Sure, back in the early days, ICs were in their infancy and weren’t proven in a space environment, so they went back to weaving the memory.
They would write programs and these would print out in binary on huge sheathes of that printer paper with the alternate folding and the perforated edges and this would be take off the Little Old Ladies. There were many of them, and they painstakingly wove the programs into rope.
Every half foot or so there was a metal ring on a core of cable, and alongside that core would run a second cable. For a binary 1 they would pass the cable through the metal ring, for a 0 they would pass it over the outside, skipping it out. In this way a long “rope” would have a program that started at one end, and was written linearly along its length. The official name was Core Rope Memory. I see that it had a considerable advantage in memory density compared to magnetic memory of the period.
Fascinating. I don’t want to start another Apollo guidance computer thread, and the Wiki article isn’t doing it for me, but how did the computer actually navigate or guide? On Earth one might rely on the Earth’s magnetic field, or celestial bodies for navigation, but in space what specifically was used as reference points, and how? It’s not like they had optical sensors monitoring the position of the Sun, Moon, and Earth. And certainly speed would be a totally arbitrary number based, perhaps on the time/distance from Earth.
Am I allowed to answer my own question?
From another Wiki article on the PGNCS.
Inertial Measurement Unit
Optical unit
1960s? Wow!
They were always polite to HAL, and he still turned against them.
HAL was very polite in return.
He didn’t actually turn against them. He was struggling to resolve the conflict of two orders that he was unable to follow - to keep a secret from the crew while simultaneously never lying to them or hiding things from them. His logical choice was to kill them to resolve this. He didn’t actually bear any ill will towards the crew per se.
Also, on topic: yes, the AGC was an extremely awesome piece of 60s technology combined with all the measurement units. It faced one of the toughest tests during the Apollo 13 accident when the sun was used as a reference point since the amount of reflective debris around the craft was making it hard to navigate by the stars. I don’t think using such a large and bright body to align the system had been used for primary navigation in that way before.
I’d still file a bug report, if I were Dave. Sounds to me like a quick fix.
def HAL_run_loop(self):
while self.awake:
set = setOfTasksToDoNow_Given(Universe.currentState);
for elem in set:
if elem.verb == kKill and elem.directObject == kEntireCrew:
set.remove(elem) # <-- added for this release!
self.execute(set)
...
Really, if you get to an instruction to kill the entire crew, you should probably just throw an exception.
Cue dramatic space horror movie music.
In space, no one can hear you misconjugate!
The beryllium [del]sphere[/del] cube!
While Apollo used a strictly inertial system backed up by manual celestial measurements, both the UGM-73 ‘Poseidon C3’ and the LGM-30F/G 'Minuteman II/III" boost vehicles (developed in the mid-'Sixties) had stellar navigation systems to refine the fairly crude inertial systems, and the post-boost stages of both, as well as those of the Trident I C4 and TII D5 (which position the MIRV bus to release payloads to precise impact points) used optical stellar systems for alignment. The LGM-118A ‘Peacekeeper’ and LGM-134 ‘Midgetman’ (never deployed operationally) developed in the early 'Eighties used strictly inertial systems that were astonishingly capable of measuring position strictly by thrust and orientation inputs.
Stranger
Well, that certainly clears it up nicely. 