Hi:
The SAGE computers, which I had the pleasure of seeing the last two
operating, had an all vacuum tube array of core that consisted of 33
planes of 64 x64 cores for about 16K worth of memory. These where all
vacuum tube computers. IBM offered a 4K all vacuum tube core storage
unit for the 701 and 702, the same unit was built into the 704 and the
705 had a larger core storage with 35 planes of 50 x 80 cores. The
Remington Rand Corp. and the RAND Corp. also shipped computers that used
core for main storage in the mid 50s which likely used vacuum tube
drivers. At that time there where apparently no transistors available
that could supply the drive current required for core memory.
On 6/23/13 5:29 PM, Bob Camp wrote:
Hi
I've both used and worked on core memory machines. They ones I have seen all used solid
state devices in the core memory sections of the machine. I've never heard of a pure tube
machine with more than "register sized" core.
Bob
On Jun 23, 2013, at 1:47 PM, Chris Albertson <albertson.ch...@gmail.com> wrote:
Magnetic cores were not invented until the 1950's and realy cam into use as
tubes were beibg replaced by SS. But there isnot reason yu can't build a
tube computer with core memory. I have actually seen and used a computer
that had one megabyte of core memory. The stuff was still in use in the
late 1970s 1MB was a lot of RAM in 1975.
You can have very good reliability with tube circuits. It was just that
few people wanted to pay for it. Down time was cheaper. It is not hard to
add redundancy to a circuit but it does have a huge cost multiplier effect.
4x or 5x the price. One simple way is to use 3 or 4 tubes with their
output tied to a resistive adder. If one tube fails the result (because it
is binary) is still the same. With computers no one would pay for fault
tolerant design until it was reasonably affordable. Even today we mainly
just put up with failure except for airplane controllers, huge web sites
like Amazon and the like.
On Sun, Jun 23, 2013 at 9:53 AM, Brian Alsop <als...@nc.rr.com> wrote:
On 6/23/2013 14:40, Bob Camp wrote:
Hi
AC137 doesn't ring any bells. True tube core (no solid state at all)
isn't something that was dimensioned in K words. A couple hundred words was
pretty big stuff. "Quite a bit" of core done that way is a lot of tubes. As
the number of tubes goes up, the time to failure comes down….. hours …
minutes … who knows.
Bob
Yeah, it gets to be like the cross country aircraft races in the 20's. The
mechanic had to fly with the pilot. (The MTBF of many of the engines used
was measured in hours.) If necessary he had to climb out on the cowling
while in flight to change plugs and fix whatever possible without landing.
What would OSHA say about that?
Needless to say future generations will probably find lots of aircraft
spark plug artifacts in their digs.
Brian/K3KO
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