Computer Pioneer Geoff Tootill Passed Away (theguardian.com) 36
"Computer pioneer Geoff Tootill passed away in October," writes long-time Slashdot reader tigersha. Born in 1922, Tootill began his career troubleshooting airborne radar systems during World War II, leading him to some pioneering research in the late 1940s. "He worked on the first computer that stored a program in main memory, as opposed to a paper tape, and actually had the opportunity to teach Alan Turing and debug one of Turing's programs." The Guardian remembers:
The computer could store just 32 instructions or numbers using a single cathode ray tube. The machine first worked in June 1948, taking 52 minutes to find the highest factor of 262,144, involving about 3.5 million arithmetic operations. The following year, Tootill transferred to Ferranti, the Manchester-based electrical engineering company, to specify a full-scale computer...the world's first commercially available computer.
That was the Ferranti Mark I, first released in 1951.
Tootill passed away at the age of 95.
That was the Ferranti Mark I, first released in 1951.
Tootill passed away at the age of 95.
Re: (Score:1)
Szilard invented the atom bomb (and got patent for it). He was friends with Einstein and shared a patent with him for a gas powered refrigerator. He was the one who wrote to Roosevelt warning him of the chance that the Nazi's could build such a bomb, but did not have the clout or notoriety of Einstein, so convinced Einstein to send the letter.
It's scary to think what would have happened if Hitler had waited a few more years before starting the war. Germany would have been invincible.
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"It's scary to think what would have happened if Hitler had waited a few more years before starting the war."
Not really, for a LOT of reasons apart from the A-bomb that I won't go into.
As for the A-bomb, the Third Reich was extraordinarily disorganised, to a large extent because of Hitler's attitude of "divide and rule" towards both his generals and administration. He enjoyed setting ministries to squabble among themselves and never trusted the higher echelons of the Army or his scientists That anything e
Farewell (Score:2, Insightful)
Farewell Sir, and thank you for everything that you helped create.
In modern terms (Score:4, Informative)
The computer could store just 32 instructions or numbers using a single cathode ray tube.
About the same as our average current politician.
The machine first worked in June 1948, ...
[ see above ]
Re: (Score:1)
A single cathode ray tube is more than anyone will ever need.
highest factor of 262,144 (Score:3)
FTA: "52 minutes to find the highest factor of 262,144, involving about 3.5 million arithmetic operations"
I wonder what algorithm they were using. 262144=2^18, so the highest (prime) factor is 2, and almost any algorithm (such as the sieve of Eratosthenes) would try 2 first.
Re:highest factor of 262,144 (Score:4, Interesting)
So I'm guessing they started with a "factor", example 2, added it together repeatedly until it equalled or was greater than the target, remembering how many additions were made. If equal to the target, repeat the addition half the number of times, and replace that with the old target, and output 2 as a factor. If greater than the target, try the next "factor" 3,5,7 etc etc.
Repeat until target = 0
It's surprising how relatively recent native MUL and DIV operations are in processors.
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Some of the "one-off" computers had them, the binary floating point Z3 had multiply and divide in 1941 (but no condional branching, ha!). ENIAC, decimal computer, finished in 1945 did too.
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I wondered this also. I'm guessing at that time, they perhaps didn't have MUL or DIV instructions, or even the concept of SHL or ROL which would have allowed a test for "divisible by 2".
A single shift left can be replaced by adding a register to itself. In some ISAs, one might be preferred to the other if they affect different flags.
Re:highest factor of 262,144 (Score:4, Informative)
From the Wikipedia article on the computer (the "Manchester Small-Scale Experimental Machine", aka "Baby"):
The first of three programs written for the machine found the highest proper divisor of 2^18 (262,144), a calculation that was known would take a long time to run—and so prove the computer's reliability—by testing every integer from 2^18 1 downwards, as division was implemented by repeated subtraction of the divisor. The program consisted of 17 instructions and ran for 52 minutes before reaching the correct answer of 131,072, after the SSEM had performed 3.5 million operations (for an effective CPU speed of 1.1 kIPS).