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How Powerful Was the Apollo 11 Computer?

How powerful was the Apollo 11 computer?
How Powerful Was the Apollo 11 Computer?

How Powerful Was the Apollo 11 Computer?

I got to thinking, how powerful was the computer that took Man to the Moon back in 1969? How does the Apollo computer compare to the iPhone? (Who wants to go to the Moon, anyway?)

It turns out that’s a tough comparison to make, as the simplest of iPhones is so advanced compared to the technology used in Apollo’s guidance system that it’s hard to believe they both came from the same planet, and we can be pretty sure that we’re dealing with some really archaic hardware.

Indeed, those Big Machines were nothing short of amazing. Comparing the Apollo Guidance Computer (AGC) to an IBM PC XT. Did you know that the 8088 which formed the basis for the IBM PC, released in 1981, just a decade after Apollo 11’s trip to the Moon, had eight times more memory than Apollo’s Guidance Computer (16k, vs the Apollo’s 2k). The IBM PC XT ran at a dizzying clock speed of 4.077MHz. That’s 0.004077 GHz. The Apollo’s Guidance Computer was a snail-like 1.024 MHz in comparison, and it’s external signaling was half that.

Internally, the architecture of 8086 had 8 16-bit registers available to work with. It could keep track of eight registers, the Apollo Guidance Computer held just four.

The most amazing part that will blow you away isn’t so much the hardware, as the software they used to get to the Moon. In fact, the real-time operating system in the Apollo 11 spacecraft could multi-task eight jobs at a time, something we take entirely for granted today, but no small feat for the time it was developed.

Multi-tasking however, wasn’t quite as we now think of it. Our operating systems use pre-emptive -multitasking, where the operating system itself is in control of the execution and can stop any program at any time. The AGC relied on non-pre-emptive multi-tasking, whereby programs had to relinquish control back to the OS periodically.

The Apollo system also implemented a virtual machine which offered more complex instructions, and could be used to perform more advanced mathematics. For its time, this was way-out stuff in 2k of memory and 32k of storage. The OS managed transition between native instructions and the instruction set of the virtual machine, which let developers mix and match the hardware level instructions with the virtual instructions within the same assembler code.

Even more, the Apollo 11 was actually the advanced “Block II” version of the AGC – the earlier missions had relied upon as little as 24k of core read-only storage, and only 1k of main memory!

And what about interface? The AGC was way switches and blinking lights, and every command was entered in a combination of “verb noun pairs”, which would be input as numbers. These numbers were translated into English on a painted sign in the spacecraft.

The Apollo Guidance Computer had only one error message, and when it flashed, it meant the real end was near. On the Apollo 11 mission a 1201 error, and then a 1202 flashed causing enormous concern on the lander and back on Earth, after the spaceship crew had mistakenly left one radar system on, while the landing crew used a second system to determine the distance to the ground. The computer was taking in too much data to function, and left the crew in the lurch.

So, when you think about all those amazing manned missions to the Moon, and what it took to get there, keep in mind that had the complexities of the eventual AGC been understood when the NASA team began to design it, they likely never would have started, as they would have considered the computer far outside the available technology of the day.

We take interplanetary travel for granted today. One day Man is going to do the same with interstellar travel. And people will smile just looking at today’s iPhones and iPads, so obsolete and so out-of-date toys the Humans had to deal with to communicate.

­See also:

  • Apple Encyclopedia: all information about products, electronic devices, operating systems and apps from experts.
  • the best place to sell my used iPhone online. Top cash guaranteed. Free quote and free shipping. BBB A+ rated business.
View Comments (7)


  1. G. Foxe

    December 10, 2017 at 8:17 pm

    “We take interplanetary travel for granted today.”
    Which planets have we been to?

    • Lana

      December 11, 2017 at 3:31 pm

      Moon, it’s a planet, anyway. Mars and Venus, we’ve been there. Jupiter, Saturn and Uranus, I think, have been explored by Voyagers 1 and 2 and Cassini. So yes, we’ve been there and hopefully we’ll go back there with new technologies.

      • Kevin

        January 30, 2018 at 3:47 pm

        Our moon isn’t a planet.

  2. S W

    July 26, 2018 at 3:55 am

    At most, men and women have traveled 260 miles or so above the earth’s surface, orbiting in the international space station or space shuttle. That’s it. No one has set foot on the Moon because no one as yet has developed the technology to bring astronauts there and back alive.

    • Kevin Dufresne

      August 27, 2018 at 9:46 pm

      So, you think that the manned missions to the Moon were fakes?

    • Chris Higgs

      October 6, 2018 at 6:10 pm

      Absolutely. NASA themselves have since admitted that we’ve never reached further than low earth orbit. Inverse Square Law proves that the whole thing was made up. Don’t believe me? Look it up.

  3. Siegfried Marquardt

    October 20, 2018 at 6:06 pm

    Mathematics and Physics refutation of Apollo 11 to N

    1. After Sternfeld (1959) only two 14-day constellations and a 60-day scenario should exist to reach the moon with an artificial spacecraft from Earth and land on the earth. Regardless of the theoretical facts and details of Sternfeld, required the research satellite SMART I, which was launched end of September 2003, 49 days until the moon level and five months until the probe einmündete in lunar orbit. And successfully running in the December 2013 lunar expedition of Chinese probe Chang`e-3 proved impressively that it takes at least 14 days to cope with the distance from the Earth to the Moon. This Apollo 11 would already impressively refuted empirically because a putative 8-day regime that is allegedly practiced with Apollo 11 and drilled, astrophysical theoretically and empirically does not exist!

    2. The cosmic radiation, which would have affected the astronauts within eight days would have been absolutely hopeless! After all, you would have incorporated a lethal dose of at least 11 Sv to 26 Sv depending on the chosen model calculation. if you are in this context to the high-energy particle density in the cosmos and to the particle stream the sun with the solar constant of 8.5 * 1015 MeV / m * s thinking. After meeting Lindner (1973) per second per square meter in 1300 protons from the cosmos to the Earth’s atmosphere. Extrapolating this energy to the eight days-long “lunar mission” high, would result in the massive dose of more than 1000 Sv! The astronauts had the flight to the moon and earth not survive back in any case, since the absolute lethal dose is 10 Sv. This Apollo 11 and N would be absolutely refuted!

    3. It was missing a total of 90 tons of rocket fuel to get from Earth to the moon and from there back to Earth by NASA on the given loop-shaped trajectory. Furthermore, the amount of fuel and the former fuel parameters would have a moon charge and even boot from the moon under the former conditions impossible. Alone for the transition from the elliptical trajectory close to the Moon would be for the braking of the CSM + LM with a total of 45.3 t mass of the 2.3 km / s to 1.5 km / s for the lunar orbit [1- (1: 2,72 high (0, 8: 2,6) ] *45,3 t = 45.3* (1 -0,74) * 45.3 t = 0.26 *45,3 ≈ 12 tons of fuel have been necessary! The remaining three tons a moon landing would not have been possible and start from as little moon! On the Moon, LM did not have 14 t, but 15-8 = 7 t!

    4. Reconstruction of the command module at a predetermined height by NASA of 3.23 m and a diameter of 3.9 m, resulting in the end can only result a total volume of about 12.9 m³, showed that after deduction of the declared internal volume of 6.23 m³ volume of the outer cell of the command module only about 6.7 m³ could include. With a mass of 5.9 t the density of the command module would thus have to be only about 0.9. This would “afford” not even paper or cardboard! Another mathematical optimization was then that the outer cell only from a 2.5 cm thick aluminum layer could exist – without the heat shield. If one half of the total mass of 5.9 tonnes for a heat shield as a basis, the heat shield could consist of only 2 mm thick steel. A commentary is superfluous almost: The command module would be in the earth’s atmosphere with a theoretically calculated braking temperature of at least 45,000 K like a shooting star burns!

    5. Even in a preliminary phase in the reconstruction of the Lunar Module according to NASA parameters after deduction of the alleged approx MTr = 10.8 t invoiced fuel mass of the starting compound with Mo = 15 t the Lunar Module merely remain only 4.2 t to empty weight, already with the material reconstruction of the cabin (about 1.1 tons), parts of the outer cell (1.3 t), and the declared weight (1.7 t), without taking into account the weight the astronauts with their space suits (400 kg), the mass of the tank and the two main engines of the Lunar Module (…) of 600 kg exceeded. Total lacked exceeding 3 tonnes construction mass, could be as originally stated by NASA and how 11 is impressive and convincing with the total reconstruction of the Luna module of Apollo.

    6. Furthermore, the pendulum behavior of the flag on the moon is extremely treacherous! For the pendulum period T, which is physically connected to the pendulum length l (l = 0.7 m) and the gravitational acceleration g (g = 9.81) to

    T = 2 * π * √ l: g (1)

    calculated, would have on the Moon

    T = 6.28 * √ 0.7 m 1.6 m / s ≈ 4.2 s (2)

    respectively. In the TV film documentaries period lasts but close to 2 s, as indicated on the earth. The exact calculation of the period for the earth yields accurate

    T = 6.28 * √ 0.7 m / 9.81 ≈ 1.7 s. (3)

    This time difference of 2.5 s is serious! In addition, a slightly damped periodic oscillation would arise on the moon, because there is no atmosphere is present on the moon. The increasing vibration is true but almost aperiodic. Summary: The shooting took place so unique on earth!

    7. A mechanical instability of the lunar module would have made an intact moon landing impossible! Every person on the planet has probably already seen a failed rocket launch when the rocket has already picked up a few meters from the launch pad and then fail the engines and do not produce more power. As a result, the rocket moves the physical laws of gravity accordingly again towards the launch platform and then tilts due to the mechanical instability simply because the center of gravity has changed dramatically. This would also be the fate of the lunar module of Apollo 11 was because shortly before landing an absolute instability of the ferry would have been! Because: Full expected gross, the rising level would have had to ground just before landing on the moon for about 5 t and the descending stage would have received under the fuel consumption of only 8 t only about 2 tons of empty weight had. As the focus of the Lunar Module must have lain on the moon exactly at 2.10 m before landing the ferry across the nozzle, the torques would like 2.5: 1 to 3: 1 behaved. For an absolutely unstable mechanical system would be active! Even the smallest vibration, such as vibrations through the engine or pressure fluctuations in the effluent gases in the nozzle of the engine have the lunar position ferry can easily tip over! A moon landing would indeed be “successful”, but a return from the moon would have been so impossible. However, since 11 have fortunately survived the imaginary adventures all actors of Apollo, it can be concluded razor sharp, no moon landing took place.
    The solution of the physical problem is that the focus of a lander simply must be at the level of the nozzle of the engine, such as the Chinese realize this in December 2013, and practiced.

    P. S. By the way, the author had the skeptical thoughts on the instability of the lunar module landing on the moon more than 45 years ago spontaneously for about 1 s had entertained!

    Siegfried Marquardt, Kingswells

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