In the 2018 film “First Man” about Neil Armstrong’s journey to becoming the first human to set foot on the moon, a computer plays a starring role in the dramatic moments before the lunar module touches down on the surface.Taken directly from the audio recording of the landing, the scene features a blaring alarm from the Apollo Guidance Computer as it manages the descent and forward motion of the spacecraft. Armstrong and pilot Buzz Aldrin report a couple of instances of the alarm, designated a 1202, and then another, a 1201. In both cases, Mission Control in Houston tells the astronauts to continue, the mission is a “go."It’s a dramatic moment both in real life and in the film, but it’s also a pivotal moment in the history of computing. The alarm was an indication that a key feature of the guidance computer was doing just what it was designed to do - make landing on the moon the computer’s top priority.While the computer systems that got humans to the moon and back in July 1969 are considered primitive compared to the smartphones we carry in our pockets or the smartwatches we wear on our wrists 50 years later, they were remarkable for their time. The software created for the guidance computers required new approaches to programming that are still used today.“It was the first time any vehicle that carried people had submitted itself to being controlled by a digital computer,” said Don Eyles, a computer scientist who, fresh out of college, landed a job at the Massachusetts Institute of Technology’s Instrumentation Laboratory in 1966. He wound up working on the guidance system for the lunar module, and wrote about his experiences in a 2018 book, “Sunburst and Luminary: An Apollo Memoir."Big body, little brainThe computers on both the lunar module and the command module were the same in terms of hardware. Both weighed about 70 pounds, were encased in gold-colored cases and were bolted to the walls of their respective spacecraft. Eyles said 10 pounds of that weight likely was the memory on the computers, composed of iron rings with wires passing through them and wrapped around them. Called rope core memory, it was limited to just 2 kilobytes of memory that could be erased and rewritten, known today as random access memory, or RAM.Compare that to the 8 gigabytes of silicon-based RAM in Samsung’s latest smartphone, the Galaxy S10. That mobile device has 4 million times more rewritable memory than what was in the Lunar and Command module’s computers.While modern computers and smartphones have high-resolution displays and can use touch, voice and keyboards for input, the Apollo guidance computers were far more rudimentary. Their Display and Keyboard Unit, or DSKY, had a simple numeric keypad, a series of status lights and a numeric digital display. Commands were painstakingly typed as number combinations by the astronauts, including when NASA wanted to make changes to the code.In 1971, during the Apollo 14 mission, Eyles was tasked with writing a change in the Lunar Module’s software after a switch malfunctioned on the lander. New commands were needed to bypass the switch, and Eyles had only two hours to rewrite the code or the landing would be aborted. According to a Rolling Stone magazine article about the incident at the time, entering the new program involved typing in 26 sets of five-digit numbers. The code was finished and punched into the computer with just 10 minutes to spare.MultitaskingThe software that ultimately controlled the descent to the moon, as well as other aspects of the Apollo 11 flight, was unique for the time as well. Unlike other computer systems, the Apollo Guidance Computer could multitask, something a modern smartphone now excels at. It also could prioritize tasks that were given to it.Eyles credits these advances to J. Halcombe “Hal” Laning, who came up with a way for multiple jobs to be prioritized, allowing for the computer to handle more than one task without crashing. His approach had never been tried before and is still used in programming today.“The memory was so small, and the computer so slow, that this was necessary to pack the most processing power into it,” Eyles said.And it was this system that was at work when the now-infamous 1202 and 1201 alarms began blaring during Apollo 11’s descent to the moon.As the Lunar Module was descending, the guidance computer had been assigned multiple tasks, but navigating to the surface of the moon was Priority 1. The secondary tasks were halted, causing the computer to issue the alarm that it had too much to do. This was disconcerting to the astronauts.“The display and keyboard went blank at one time for 10 seconds,” Eyles said.Armstrong asked Mission Control for a “reading” on the 1202 alarm, and back in Houston guidance experts scrambled for an answer. A 26-year-old guidance controller named Steve Bales gave “thumbs up” to indicate it was OK - Eyles said he was too scared to use words - and the mission continued.Today, Eyles is an artist, writer and still works in computer science. He carries a smartphone, as you’d expect, and appreciates how far our computing capabilities have come. But there’s one thing he doesn’t like about modern mobile devices.His smartphone of choice is Apple’s iPhone SE, an older, smaller model that was recently discontinued by Apple.“Smartphones are just getting too big,” he said. He even went so far as to buy a second one as a backup. Just in case.

In the 2018 film “First Man” about Neil Armstrong’s journey to becoming the first human to set foot on the moon, a computer plays a starring role in the dramatic moments before the lunar module touches down on the surface.

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Taken directly from the audio recording of the landing, the scene features a blaring alarm from the Apollo Guidance Computer as it manages the descent and forward motion of the spacecraft. Armstrong and pilot Buzz Aldrin report a couple of instances of the alarm, designated a 1202, and then another, a 1201. In both cases, Mission Control in Houston tells the astronauts to continue, the mission is a “go."

It’s a dramatic moment both in real life and in the film, but it’s also a pivotal moment in the history of computing. The alarm was an indication that a key feature of the guidance computer was doing just what it was designed to do - make landing on the moon the computer’s top priority.

While the computer systems that got humans to the moon and back in July 1969 are considered primitive compared to the smartphones we carry in our pockets or the smartwatches we wear on our wrists 50 years later, they were remarkable for their time. The software created for the guidance computers required new approaches to programming that are still used today.

“It was the first time any vehicle that carried people had submitted itself to being controlled by a digital computer,” said Don Eyles, a computer scientist who, fresh out of college, landed a job at the Massachusetts Institute of Technology’s Instrumentation Laboratory in 1966. He wound up working on the guidance system for the lunar module, and wrote about his experiences in a 2018 book, “Sunburst and Luminary: An Apollo Memoir."

Big body, little brain

The computers on both the lunar module and the command module were the same in terms of hardware. Both weighed about 70 pounds, were encased in gold-colored cases and were bolted to the walls of their respective spacecraft. Eyles said 10 pounds of that weight likely was the memory on the computers, composed of iron rings with wires passing through them and wrapped around them. Called rope core memory, it was limited to just 2 kilobytes of memory that could be erased and rewritten, known today as random access memory, or RAM.

Compare that to the 8 gigabytes of silicon-based RAM in Samsung’s latest smartphone, the Galaxy S10. That mobile device has 4 million times more rewritable memory than what was in the Lunar and Command module’s computers.

While modern computers and smartphones have high-resolution displays and can use touch, voice and keyboards for input, the Apollo guidance computers were far more rudimentary. Their Display and Keyboard Unit, or DSKY, had a simple numeric keypad, a series of status lights and a numeric digital display. Commands were painstakingly typed as number combinations by the astronauts, including when NASA wanted to make changes to the code.

In 1971, during the Apollo 14 mission, Eyles was tasked with writing a change in the Lunar Module’s software after a switch malfunctioned on the lander. New commands were needed to bypass the switch, and Eyles had only two hours to rewrite the code or the landing would be aborted. According to a Rolling Stone magazine article about the incident at the time, entering the new program involved typing in 26 sets of five-digit numbers. The code was finished and punched into the computer with just 10 minutes to spare.

Multitasking

The software that ultimately controlled the descent to the moon, as well as other aspects of the Apollo 11 flight, was unique for the time as well. Unlike other computer systems, the Apollo Guidance Computer could multitask, something a modern smartphone now excels at. It also could prioritize tasks that were given to it.

Eyles credits these advances to J. Halcombe “Hal” Laning, who came up with a way for multiple jobs to be prioritized, allowing for the computer to handle more than one task without crashing. His approach had never been tried before and is still used in programming today.

“The memory was so small, and the computer so slow, that this was necessary to pack the most processing power into it,” Eyles said.

And it was this system that was at work when the now-infamous 1202 and 1201 alarms began blaring during Apollo 11’s descent to the moon.

As the Lunar Module was descending, the guidance computer had been assigned multiple tasks, but navigating to the surface of the moon was Priority 1. The secondary tasks were halted, causing the computer to issue the alarm that it had too much to do. This was disconcerting to the astronauts.

“The display and keyboard went blank at one time for 10 seconds,” Eyles said.

Armstrong asked Mission Control for a “reading” on the 1202 alarm, and back in Houston guidance experts scrambled for an answer. A 26-year-old guidance controller named Steve Bales gave “thumbs up” to indicate it was OK - Eyles said he was too scared to use words - and the mission continued.

Today, Eyles is an artist, writer and still works in computer science. He carries a smartphone, as you’d expect, and appreciates how far our computing capabilities have come. But there’s one thing he doesn’t like about modern mobile devices.

His smartphone of choice is Apple’s iPhone SE, an older, smaller model that was recently discontinued by Apple.