On Sat, 14 Jan 2006, andrew kelley wrote:

> Why wouldnt they use PROM's or OTP's?  Wouldn't those tend to have
> longer lifetimes?
>
>> I'm also thinking perhaps of some of these spacecraft (eg Voyager)
>> that might have a very long life. Do they not use EPROMs of the
>> day ? If so, what's to stop their programming just fading away - or
>> are they not expected to retain it anyway and are simply space junk
>> with some transmitting capability ? Do they have special long-
>> retention NASA cells ?

They have special 'long retention' wire memory or plated memory. The 
code is effectively burned into what amounts to a printed circuit board 
or weaved through memory cores. Unless someone unthreads the wire or 
cuts some board traces the code stays the way it was made.

Peter
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