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A friend today mentioned in conversation:

You know that iPhone 6 you're carrying in your pocket. It has more computing power than the Cray supercomputers of the 80s.

That sounded vaguely right, but I wasn't sure.

My question is: Is the iPhone 6 more powerful than a Cray supercomputer?

  • More powerful in terms of what, GFLOPS? – nohillside Apr 11 '15 at 12:10
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    I wasn't going to specify a particular metric - feel free to select the most appropriate one. – hawkeye Apr 11 '15 at 12:11
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It would really depend on which end of the 1980s we choose. A Cray 2, circa 1985 would be a good midline choice.

CPU speed of the Cray-2 was about 250MHz, with what we would today call 4 cores. 256Megs of memory but at 64bits per address instead of 8, or as we would call it today 2 GB of RAM. In terms of raw power it has been compared to an iPad. that's if you use a CPU benchmark.

However, supercomputers are usually optimized for parallel tasks or rather staggering amounts of input-output. It really isn't practical to say "my phone could replace supercomputer X from year Y" as they aren't capable of performing the same tasks. If we jump back a couple more generations we can say that an iPhone could have run the entire Apollo program assuming we hooked it up to a signal booster (and hold it the right way).

The iPhone beats the Cray hands-down in power consumption: 200 kW, 480 V 3-phase power coming in resulting in over 2000 amps internal power. Pressurized liquid cooling with an external heat exchanger the size of a car.

Looks awesome sitting in your dedicated computing center though.

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    You'd look silly holding up a Cray & typing with your thumbs though ;) – Tetsujin Apr 11 '15 at 16:17
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    Todays iPhone battery life times suggests that this 480V 3-phase power supply was not a bad idea at all – Hagen von Eitzen Apr 11 '15 at 20:24
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    Apparently Apple bought a Cray to help design the new Macintosh. Around the same time, Seymour Cray bought a new Macintosh to help him design his new Cray. – Laconic Droid Apr 11 '15 at 23:59
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    Was the "256 Megs" of memory therefore 4 gibibytes (8-bit bytes) in 256 mibi-words? Or was it 256 mibibytes of memory in 32 mibi-words? (Using 'word' for the 64-bit unit of addressable memory.) Either way, in raw RAM, the iPhone 6 must be right up there with it (ahead if it was 256 MiB). – Jonathan Leffler Apr 12 '15 at 0:38
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    We would say it had 2GB of memory. 256M memory locations of 64 bits each, so multiply by 8. In the mid-1980s that was an absolutely staggering amount - home computers had 128kB. iPhone 6 has 1GB so it's still ahead there. – paul Apr 12 '15 at 1:27

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