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The machine that made the moon missions possible

We've all been there: you work on something important, your computer crashes, and you lose all your progress.

Such a failure was not an option during Apollo's missions when the computer was first loaded with the management of flight control systems and life support – and therefore the lives of astronauts on board.

Despite the infamous false alarms during the lunar descent that sent commander Neil Armstrong's heartbeat, it was a tremendous success that laid the foundations of everything from modern avionics to multi-tasking operating systems.

Here are some of the ways that the Apollo (AGC) computer, millions of times less powerful than the smartphone 2019, shaped the world we live in today:

– Microchip revolution –

Integrated circuits, or microchips, were a necessary part of the miniaturization process that allowed computers to be placed on board a spacecraft, unlike the giant vacuum tube technology that came before.

The credit for their invention is by Jack Kilby of Texas Instruments and by Robert Noice, co-founder of Fairchild Semiconductor, and later by Intel in Mountain View, California.

But NASA and the Department of Defense – who needed micro-chips to steer their Soviet-led ballistic missiles Minuteman – significantly accelerated their development by producing demand that facilitated mass production.

"They had these incredible, absolutely crazy safety requirements that nobody could imagine," Frank O'Brien, a historian and space flight, author of "Apollo's Computer: Architecture and Operation."

In the early 1960s, the two agencies purchased almost all microchips produced in the United States, approximately one million, said O'Brien, forcing manufacturers to improve their design and build schemes that went on longer than their early life cycle. a few hours.

– Multitasking –

Modern computers, such as the smartphone in your pocket, can usually perform multiple tasks simultaneously: working with emails in one window, GPS in another, different social networking applications, all the time ready for incoming calls and texts,

But in the early age of our computers, we thought of them in a very different way.

"Not many of them were asked, they were asked to crush numbers and replace the people who would make them on mechanical addition machines," said Simus Tuoyi, chief of space systems at Draper, which is being separated from the MIT Instrumentation Laboratory , developed the Apollo Guidance computer.

All of this changed with the Apollo Guidance Computer, a briefcase machine that had to handle a number of vital tasks, from navigating the ship to the oxygen generator, the carbon dioxide heaters and scrubbers.

Instead of a computer operator who gives the machine a set of calculations and leaves it for hours or even days to make the answer – all this should be done in a time-sensitive manner with interruptions and the possibility for users (astronauts) to give commands in real time.

NASA thought it was necessary to have a computer on board to deal with all these functions if the Russians were trying to silence the radio communications between the ground control in Houston and the US spacecraft, and because Apollo was originally intended to go deeper into The solar system.

All this requires software architecture, much of which is engineered by Hal Lanning.

– Real-time entry –

They also needed new ways of interacting with a machine over a punch-card programming time.

The engineers came out in three key ways: the keys that you still find in modern cockpits, the hand-held controller that is connected to the world's first digital screen suspension system and "display and keyboard", shortened to DSKY (pronounced "dis- key ").

Astronauts will enter double-digit verb and node codes to execute commands such as launching or locking a star if a ship that relies on an inertial guidance system maintains pitch stability, winding, and slope, has started to deviate from course.

O'Brien uses the metaphor of a tourist who visits the United States and is hungry but does not know much English, and can say "Eat pizza" to convey the basic meaning.

– Passing the test –

The most tense moment of Apollo 11 came during the last minutes of his descent on the moon's surface when the alarm bells on the computer began to ring and appear to have crashed.

Such an event may have been catastrophic, forcing the crew to interrupt their mission or even send the ship out of control on the surface.

Back in Houston, an engineer realized that while the machine was temporarily overloaded, intelligent programming automatically allowed him to throw less important tasks and focus on the landing.

"The way the computer handled the congestion was a real breakthrough," says Paul Ceruciu, a Scientist at the Smithsonian Space Electronics Institution.

O Brian noted that while the AGC is weak on modern computing standards with a clock rate of 1 Mhz and a total of 38Kb of memory, such comparisons violate its true caliber.

"With this terribly small capacity, they were able to do all the amazing things we now see as completely normal," he said.

IA / she



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