Joanna Nelius at Gizmodo, writing about the CPU at the heart of NASA’s newest rover:
The PowerPC 750 was a single-core, 233MHz processor, and compared to the multi-core, 5.0GHz-plus frequencies modern consumer chips can achieve, 233MHz is incredibly slow. But the 750 was the first to incorporate dynamic branch prediction, which is still used in modern processors today. Basically, the CPU architecture is making an educated guess on what instructions the CPU is going to process as a way to improve efficiency. The more information that’s processed, the better the chip gets at predicting what it needs to do next.
However, there’s a major difference between the iMac’s CPU and the one inside the Perseverance rover. BAE Systems manufactures the radiation-hardened version of the PowerPC 750, dubbed RAD750, which can withstand 200,000 to 1,000,000 Rads and temperatures between −55 and 125 degrees Celsius (-67 and 257 degrees Fahrenheit). Mars doesn’t have the same type of atmosphere as Earth, which protects us from the the sun’s rays, so one flash of sunlight and it’s all over for the Mars rover before its adventure can begin. Each one costs more than $200,000, so some extra protection is necessary.
PowerPC chips have been included in several other spacecraft, but it’s always fun to talk about when it comes up every few years.