Re: Re: Summary A

[Steve VanDevender <stevev@efn.org>]

Timothy van der Linden writes:
 > Yes, I've seen these magnetic memories (at least you can see the bits there)
 > But were that the mem-chips of 15 years ago? (Am I that old already?)

Core memory was widely used up to about 15 years ago.  Core memory
doesn't come in chip form, though; it comes in planes or blocks of
planes, with the toroidal cores strung on lattices of wire.

Core memory is still used in a few applications, although sometimes just
for historical reasons.  It does have the advantage of being
radiation-hard (find me a cosmic ray big enough to wipe out a 1 mm
ferrite core) and non-volatile.  By the time it was phased out in favor
of semiconductor memory it was also not far off in access time -- good
core had a cycle time of less than 1 microsecond, although it took a lot
more power to write it.

 > >The guys who programed them HATED them!
 > 
 > yeah, 256 kb is not too much.
 > 
 > But are todays Shuttles still having the same amount of memory?

Do you know what it takes to certify a computer system for use as a
control device in a man-rated aircraft, especially the software?
Generally you only do it once.  That's why the shuttle computers and
software are still unchanged from the time they were designed.
Supposedly they're working on a new computer design, but you won't see
it for a while.

 > Tim