roy@phri.UUCP (Roy Smith) (07/20/88)
jbn@glacier.UUCP (John B. Nagle) writes: > I could say more [about building core memory], but it's a dead technology. Is it? I remember reading somewhere (IEEE Spectrum a few years ago?) that the space shuttle uses core memory because it is 1) radiation hard and 2) static (i.e. no loss of memory on loss of power). Apparently the slow speed, power-hungry operation, and low information density are outweighted by the other factors. Can anybody corroborate this? -- Roy Smith, System Administrator Public Health Research Institute {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net "The connector is the network"
phil@titan.rice.edu (William LeFebvre) (07/21/88)
In article <3397@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >jbn@glacier.UUCP (John B. Nagle) writes: >> I could say more [about building core memory], but it's a dead technology. > > Is it? I remember reading somewhere (IEEE Spectrum a few years >ago?) that the space shuttle uses core memory because it is 1) radiation >hard and 2) static (i.e. no loss of memory on loss of power). Apparently >the slow speed, power-hungry operation, and low information density are >outweighted by the other factors. Can anybody corroborate this? Yes, the shuttle's onboard computers do in fact still use core memory. But that doesn't necessarily mean that the technology isn't dead. The decision to use core memory was made many years ago, primarily because of the reasons you state but also because it was a proven technology. They didn't want to take unnecessary chances. And at this point in time there is alot of momentum that discourages switching to something else. They do use the non-volatility to their advantage, too. It is standard procedure, once on orbit, to load one computer with the re-entry software and turn it off. They call it a "freeze dried" computer. That way, if the tape drives containing the flight software fail, they can still get down. I understand that they are seriously considering switching over to battery backed-up static RAM. They feel that they still need the non-volatility, but there are advantages to switching (less power consumed and less heat generated, and they also want to increase the machines' memory capacity). But I certainly wouldn't use the shuttle to prove that core memory isn't a dead technology. William LeFebvre Department of Computer Science Rice University <phil@Rice.edu>
eugene@pioneer.arc.nasa.gov.arpa (Eugene N. Miya) (07/22/88)
Again?! It's the special issue of CACM (case study) on the shuttle.
I no longer have the specific issue, someone didn't return it. To me,
Denning gave me his to copy which I only did the articles. Go look
this up. I'll put this in the most asked space questions file.
Another gross generalization from
--eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov
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