Alan Turing

1. Alan Turing Ashish Dasaur Ashish Dasaur

2. The Vision • Alan Turing, regarded by some as the father of computer science, was among the first to envision the power of a computer and the importance of software over hardware. • He knew the computer would mean unlimited potential in the creation and implementation of artificial intelligence and was determined to be the first to act on this belief. Ashish Dasaur

3. The Idea • In 1935, at Cambridge university, Turing conceived the idea of the modern digital computer. • This machine consisted of unlimited memory and a scanner that moves across, reading the memory and writing new data. • The actions of the scanner would be dictated by a program, changing the program would allow for change in the scanners movements and the machine’s end result. Ashish Dasaur

4. The Turing Machine • The machine he thought of is now known as the Turing Machine and helped start program-stored computers. • This machine is described as with “infinite tape that is divided into squares, any square of which may hold a non-blank symbol from a finite alphabet” (Weintraub, par. 3). • At any time, the tape of the machine is going through the reader and giving it instructions based on the symbols in the squares. • Following these instructions, Turing argued, the machine could do any calculation a human could do that did not involve any form of ingenuity, it could follow directions. Ashish Dasaur

5. Deviation From the Norm • Turing’s decision could change its function just by changing the instructions it received. This was an important deviation from analog machines that required changes in the machine itself, via switches and cables, to cause a change in the end result. • He also hinted at artificial intelligence when he said, “'What we want is a machine that can learn from experience', adding that the 'possibility of letting the machine alter its own instructions provides the mechanism for this' (qtd. in Carpenter, 123). Ashish Dasaur

6. The War Years • During WWII, Germany was in possession of the enigma, a machine that helped them encipher messages. Britain badly needed this code to be broken and turned to the logical Turing for a solution. • In 1940, while living in Bletchley Park (pictured), he and Gordon Welchman designed the British Bombe, a machine meant to decipher the enigma’s coded messages. Ashish Dasaur

7. The Aftermath • This important invention helped in the war effort and great honor was given to Turing. • He was made a top-level liaison between the US and the UK. • He began his interest in intelligent machinery and artificial intelligence. • And he was exposed to digital electronics. • All of these elements would come together in his next design, the ACE. Ashish Dasaur

8. Automatic Computing Engine: ACE • In 1945, Turing’s proposed to build the ACE, the first electronic program-oriented digital computer. • Turing’s proposal provided supplied detailed circuit designs and specifications of hardware units, specimen programs in machine code, and even an estimate of the cost of building the machine, somewhere around 11,000 pounds. • However, progress on this machine was limited due to the disorganization in NPL, National Physics Laboratory, and a lack of sufficient memory the design required, some where around the size of the early Apple computers Ashish Dasaur

9. Ideas Lead to Another Design • The heads of NPL had predicted the DEUCE, the commercial version of the ACE, would only sell three units. It sold thirty. • Numerous other designs were based on the ACE, including the G15, Packard-Bell PB250 and the MOSAIC, used for air defense during the Cold War. • The logic behind the ACE, the electric stored-program digital computer, was to be used to build the Ferranti Mark I, with programming written by Turing. This computer was Britain's first general-purpose digital computer and had working AI for chess and checkers Ashish Dasaur

10. The Problem of Memory • The ACE used mercury-filled tubes for their high-speed memory design. This was called acoustic memory as it originated from radar. Mercury delay lines were added so that the computer could get either 0’s or 1’s, indicating a certain action that should be taken. • This, however, wasted time as no random access could be obtained. Turing tried to tackle this problem and succeeded in creating optimum coding. Ashish Dasaur

11. Optimum Coding • In this system, instructions were not stored in consecutive positions but rather in relative positions that could be selected by the programmer so that each instruction could emerge when it was needed. • Each instruction also indicated where the next instruction was located. • This increased the challenge of programming but also increased the speed of the computer, a worthwhile exchange. Ashish Dasaur

12. Importance • His breakthrough in designing the fundamental idea behind every computer program was essential in builidign the first digital program-stored computer. • The implementation of this design assured that the computer could change quickly and easily to fit a new demand by simply changing the programmed instructions that it followed. • He also improved on the speed of the computer and increased its ability to process more memory-consuming assignments. Ashish Dasaur

13. His Death and After • After his work and the beginning of the Cold War, Turing was prosecuted for his homosexuality. This disallowed him any major security clearance and reduced the impact he could have in Britain’s newer developments. He was forced to go through hormonal therapy to “cure” his homosexuality. • He never fully recovered from this insult and eventually committed suicide on June 8, 1954, poisoned by cyanide. • Only in 1998, did the British government officially recognize his birthplace and unveil the official Blue Plaque there. Ashish Dasaur