November 08, 2016 Tuesday

Bedtime Story 


The Manchster SSEM Performs Its First Operation

Nobody was sure whether this baby of theirs would run and even if it did “run”, would it work.

Kilburn wrote its first program that had 17 instructions.

The task that Kilburn asked the machine to carry out was to find the highest divisor or the proper factor of 2¹⁸ which is 262,144 (In my calculator I had to multiply two 18 times to get this result).

For us, it would not be that tedious a problem as we would keep dividing by 2 and pick out the highest divisor.

The hardware of the machine was capable of doing just 2 operations, subtraction and negation (meaning additive inverse).

This limitation of the hardware would make the processing by the machine very long as it would have to test every number, or rather an integer from 262,144 to 1.

(That was the whole point; to make the machine run long).

The division involved repeated subtraction of the divisor.

For example, the machine would subtract say 65,536 from 262,144 and then continue doing so from the left over.

262,144 – 65,536 = 196,608

196,608 – 65,536 = 131,072

131,072 -  65,536 =  65,536

  65,536 -  65,636 =          0

This would be done for all the integers from 262,144 to 1 and then all the integers wherein 0 was obtained in the end would be compared.

The integer with which the least subtractions were taken to reach zero would be the highest divisor.

This experimental machine took 52 minutes to get the answer 131,072.

The machine carried out 3.5 million operations to get the answer and thus proved that the cathode ray tube memory could work.

The first stored program computer had worked!

Alan Turing who then had just joined the Manchester University mathematics department wrote the third program for this machine to carry out long division.

Williams and Kilburn reported their work to Nature that was published in September 1948.

Since this was just an experimental machine and not a practical computer, the team almost immediately decided to go for a more practical machine.

Before we jump on to the off springs of this Baby, let us go across the Atlantic and see what developments were taking place there.

Stay tuned to the voice of an average story storytelling chimpanzee or login at http://panarrans.blogspot.in/

Good night and my fellow cousin ape.

Another great educator and a teacher that I am aware of is Professor Subhashish Chattopadhyay in Bangalore, India.

While I narrate stories, Professor Subhashish an electronic engineer and a former professor at BARC, does and teaches real mathematics and physics.

He started the participation of Indian students at the International Physics Olympiad.

Do visit him here:

http://skmclasses.weebly.com/

All his books can be downloaded for free through this link:

https://zookeepersblog.wordpress.com/science-tuition-chemistry-physics-mathematics-for-iit-jee-aieee-std-11-12-pu-isc-cbse/

For edutainment and English education of your children, may I suggest this large collection of Kids Songs:

https://www.youtube.com/channel/UCMX11Z5SJQ3kgwSsFJLRIcg

First Program of the Manchester SSEM written by Kilburn on 18-7-1948. Note for example that the command:

 SUB S means subtract the number at the specified memory S from the value in accumulator and then store the result in the accumulator