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The iMac processor of the 1990s powered NASA’s persevering rover



A high-resolution image showing the number of concentric seconds before reaching the surface of Mars.

A high-resolution image showing the number of constant seconds before reaching the Martian surface.
image: NASA/JPL-Caltech

When we watch NASA Wanderers on Mars Last month, the agency certainly seemed to have to use Some kind of highThe high-tech processor in the machine.The rover must be Built on more powerful features than the components of the equipment used by our civilians, right? But wNASA Technically speaking, a dedicated processor is used to Provide power for perseverance roamers, it is not far from the world of consumer electronics-About 23 years ago.

newthe scientist The report says Perseverance Wanderer is powered by the PowerPC 750 processor, which was used in Apple’s original 1998 iMac G3-do you remember, the iconic, colorful, transparent desktop. If the PowerPC name sounds familiar, it may be because these are the RISC CPUs Apple used in its computers before switching to Intel. (Although the company is now Use your own M1 processor to return to the RISC train)

PowerPC 750 is a single233MHz processor core, compared with the multi-core frequency above 5.0GHz that modern consumer chips can reach, the speed of 233MHz is incredibly slow. But the 750 was the first to incorporate dynamic branch prediction and is still used in modern processors today. Basically, the CPU architecture is to make educated guesses about the instructions to be processed by the CPU in order to improve efficiency.The more information processed, the better the chip’s understanding of the predicateWhat needs to be done next.

However, there is a big difference between the CPU of the iMac and the CPU inside the Perseverance Robot. BAE Systems manufactured PowerPC 750 with radiation protection treatment, dKnown as RAD750 It can withstand temperatures of 200,000 to 1,000,000 Rads and -55 to 125 degrees Celsius (-67 to 257 degrees Fahrenheit). The atmosphere of Mars is different from that of Earth, Protect us from the sun’s rays, so the flash of sunlight is over before the Martian rover begins his adventure. EThe cost of each item exceeds $200,000, so some extra protection is needed.

Motorola PowerPC 750 processor, with demolding L2 cache on the CPU module through Power Mac G3.

Motorola PowerPC 750 processor, with demolding L2 cache on the CPU module through Power Mac G3.
photo: Henrik Wannheden (other)

James LaRosa of BAE Systems told NewScientist magazine: “Charged particles flying through the galaxy can pass through equipment and cause serious damage.” “Literally, it can disperse electrons; It causes electronic noise and signal spikes in the circuit. ”

But why use a processor old enough to remember when Eve 6 released the first album? It has nothing to do with cost—Those old processors are the most suitable because they are very reliable.NASAFor example, the company’s Orion spacecraft uses the same RAD750 processor.

“compared to [Intel] The Core i5 in a laptop is much slower… iIt may not be faster than your smartphone”, Matt Lemke, deputy manager of avionics at NASA Orion tell Space review Back in 2014. “However, speed has nothing to do with ruggedness and reliability. I need to make sure it always works.”

With this in mind, NASA is reasonable Will choose old technology rather than new technology.After all, when you spend money US$2.7 billion Landing robots on Mars, The important thing is that your technology must be reliable enough to stand the test of time,Up to the smallest welding circuit. Currently, RAD750 powers approximately 100 satellites orbiting the earth. These satellites include GPS, image and weather data, and various military satellites. According to LaRosa, none of them failed.


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