Let’s get one thing straight before we talk Apollo computing: Our cellphones are millions of times more powerful than the Apollo 11 lunar module computer. On the other hand, we aren’t on the moon. Instagram, maybe. But not the lunar surface.
Computer programmer and volunteer NASA historian Frank O’Brien is a little touchy about this subject. He told The Atlantic that while his smart watch may seem more powerful, it’s actually not. That’s because the NASA Apollo computers were original and fit for a purpose by 350 engineers who labored 1,400 man years. Their computers then took man to the moon.
One thing the computers didn’t do was make a warrior climb buildings, or display cat pictures. That took 40 years more and a billion humans.
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You might be amazed at how little computing power was required to get to the moon.
The Saturn-Apollo spacecraft had five onboard computers.
The Apollo Guidance Computer (AGC), according to New Atlas, looked like a brass suitcase. It was carried aboard the spacecraft and weighed 70 pounds.
In terms of computing power, the AGC was a giant leap. It had 64K of memory and 0.043MHz of speed packed into its 2-foot box. The iPhone 6 operates at 1.4 GHZ, making it 32,600 times faster than Apollo computers. The phone can perform instructions 120 million times faster, according to ZME Science.
On the other hand, the AGC didn’t crash half way along its 240,000 mile trip to the moon. It was designed not just for good reliability but for perfect reliability.
At the time MIT designed the AGC, memory technology was in its infancy (and, in fact, by the time the Apollo program took off, technology was well advanced). Still, the Apollo memory had to be indestructible — memory that could not be erased, altered, or corrupted in any way, according to New Atlas. The solution was rope memory, wherein textile workers literally wove wires through rings to hard wire the memory.
Programmed purely for priority tasks, the AGC famously gave the Apollo 11 crew a 1202 overload error just when they were attempting to land. This just meant the computer switched off everything, including what turned out to be meaningless data from radar, and restarted the top priority landing program.