On 29 Jan 2012, at 21:13, David Forbes wrote:
ENIAC was a very interesting computer. It was essentially an adding
machine, built with vacuum tube decimal counting wheels. Each
decade was a ring counter with a "count up" command. Numbers
traveled through the machine as series of pulses, one wire per decade.
The circuitry was very weird by modern standards also. The designer
of the electronics was a radio designer, and he used a bizarre DC
coupled logic ladder method that required many power supplies.
Essentially, each plate was coupled directly to the grid of the
tube in the next logical stage, so the voltage started at about
-300V and worked its way up to +300V through the logic ladder.
The weird electrical design was one of many reasons that ENIAC was
completed a year after its need, WWII, had ended. The crash design
program had resulted in a machine that took forever to actually build.
I didn't know everyone's Dad didn't work on an Eniac. My father
worked at BP's Sunbury research facility where there was an Eniac IV
and I spent hours as a kid in the room fidgeting while my father
waited for some punched tape to emerge. As I recall, the UK Eniac IV
was a joint purchase by the UK Government, BP and some UK
universities. It was certainly being used for serious work at BP
until I think around 1968, when my father asked me if I wanted any of
the pieces from it as they were scrapping it, which they did. I wish
now I had salvaged some souvenirs.
My father was a research palaeontologist. He was deemed educationally
subnormal at the age of ten but ended up with with degrees in both
botany and geology and a PhD. Through his study of foraminifera,
marine protozoa, he found a set that grew spiral 'tests' or shells
which would suddenly double back the other way on some seemingly
unrelated curve. My father used the Eniac to come up with the
underlying formula for a unique undiscovered class of mathematical
spiral which fit these and other similar forms found elsewhere in
nature. The work was never officially published, but I did have one
of his spirals engraved on my parents' joint tombstone, threaded
through the eye of a needle which symbolises my eye surgeon mother. I
am definitely the black sheep of my family.
John S
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