Re: Square root of a negative rral value
- From: "robin" <robin_v@xxxxxxxxxxx>
- Date: Fri, 28 Nov 2008 13:53:56 GMT
<nmm1@xxxxxxxxx> wrote in message news:gglkp6$uk8$1@xxxxxxxxxxxxxxxxxxxxxxxxxxx
In article <609bdfde-ec0d-4439-9b81-98b0ecc3e809@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Terence <tbwright@xxxxxxxxx> wrote:
"Terence" <tbwright@xxxxxxxxx> wrote in message
We used the Mercury computer for trajectory calculations.
First thing, was to walk into the computer with a box of double
triodes valves, unplug and replace any of the thousands with no
filaments visibly lit (while in standby mode).
Valves don't fail like that.
Even thousands of them.
Valves used in computers failed because of low emission, or
rarely because of some internal failure such as a short-circuit.
Recall ENIAC? The pessimists predicted that it would never work,
but it did.
Valve computers of the time could run for days and weeks without failure.
Robin, you missed the pint.
If JUST ONE valve fails the computer isn't going to be usefl.
There were thousands of the (d...) things, but luckily all in nice
rows you could look along.
If one was "off" or "funny-looking" you replaced it. They were mainly
one valve per memory register bit (on/off). Occasionally you would
have to change two, so you took a box of them.
But you had to check, because after your time was up, someone else was
I used a Mercury Meteor, too. Yes, they failed, but I got 5+ hours
of running, about 2 times in 3.
Those (valve) computers installed in universities were used intensively
for crystallography work, and the programs were run overnight (14 hours)
from 6pm to 8 am, and the entire weekend (from 6pm Friday to 8am Monday)
And they did.
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