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From: joefish@disk.uucp (joefish)
Newsgroups: sci.space.shuttle
Subject: Re: New Shuttle Computers (OOPS!)
Message-ID: <1991Mar07.175524.15890@disk.uucp>
Date: 7 Mar 91 17:55:24 GMT
References: <1991Mar5.201242.7993@umiami.ir.miami.edu>
Organization: Digital Information Systems of KY
Lines: 33

In article <1991Mar5.201242.7993@umiami.ir.miami.edu> jdeitch@umiami.ir.miami.edu (Jonathan Deitch) writes:
>Sorry folks,
>
>Static Ram is NOT non volatile.  It simply doesn't need refreshing.
>
>When the power goes off, so does the data.
>
>There might be hope, though.  Radio Electronics magazine recently
>had an article about standard CMOS with little ferric capacitors
>etched right onto the chip to keep the logic gates intact when the
>power is removed.  According to the article, it can keep data safe
>for up to one year.  If this technology is successful, it could be
>the next version of the flight computer. 
>-------------------------------------------------------------------
>Internet : jdeitch@umiami.miami.edu       "Good musicians execute
>                                           their music but bad ones
>Voice : (305) - 284 - 6482                 murder it !!! "

Non-volatile RAM is in large supply now.   It is used extensively
in portable computers, and even as non-volatile RAM-disks on 
portables instead of floppy drives.

I don't know if it would be better than battery powered backup RAM
or not, and it would certainly cost more.

There are several kinds of chips that are non-volatile, such as
electronically eraseable eprom and UV eraseable EPROM, but the
design of the system and the long lead time needed to develop
the required reliability may prevent some of the newer
chips from being used.
 

Joe Fischer       joefish@disk.UUCP