History of Computing. Dr. Mark Fisher School of Computing Sciences. copyright UEA slide 1

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1 History of Computing Dr. Mark Fisher School of Computing Sciences copyright UEA slide 1

2 Computing = Algorithms + Hardware + Data copyright UEA mhf@cmp.uea.ac.uk slide 2

3 How did Computing Start? Algorithms Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 3

4 How did Computing Start? Algorithms Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 4

5 How did Computing Start? Algorithms Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 5

6 How did Computing Start? Algorithms Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 6

7 How did Computing Start? Algorithms Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 7

8 How did Computing Start? Algorithms Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 8

9 How did Computing Start? Algorithms Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 9

10 How did Computing Start? Hardware Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 10

11 How did Computing Start? Hardware Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 11

12 How did Computing Start? Hardware Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 12

13 How did Computing Start? Hardware Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 13

14 How did Computing Start? Hardware Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 14

15 How did Computing Start? Hardware Timeline 500BC copyright UEA mhf@cmp.uea.ac.uk slide 15

16 Computing is born in In 1936, Alan Turing invented a theoretical computing device now called a Turing Machine. This was before electronic computers existed. He tried to give a simple model of the thought processes of mathematicians. His model has stood the test of time and represents the official model of computation that we still study today. Key concept: Turing machines are basic abstract symbol-manipulating devices which, despite their simplicity, can be adapted to simulate the logic of any computer algorithm. copyright UEA mhf@cmp.uea.ac.uk slide 16

17 Mechanical Turing Machine copyright UEA slide 17

18 State Diagram A Finite State Machine (FSM) can be specified by a state diagram. copyright UEA mhf@cmp.uea.ac.uk slide 18

19 State Diagram A Finite State Machine (FSM) can be specified by a state diagram. copyright UEA mhf@cmp.uea.ac.uk slide 19

20 State Diagram A Finite State Machine (FSM) can be specified by a state diagram. copyright UEA mhf@cmp.uea.ac.uk slide 20

21 Lego Turing Machine: Aarhus University, Denmark 1. How is the tape represented? 2. How is the tape moved left and right? 3. How are 1 and 0 represented? 4. How is the tape read 5. How is a 1 erased and replaced by a 0? copyright UEA mhf@cmp.uea.ac.uk slide 21

22 Lego Turing Machine copyright UEA slide 22

23 Universal Turing Machines and Turing Completeness Turing s first example was a machine capable of computing the sequence which he defined in terms of a table of primitive operations to be carried out by his abstract symbol manipulating machine. However, Turing realised that it would be possible to invent one universal machine that could produce ANY computable sequence a so-called Universal Turing Machine. A Universal Turing Machine can emulate any Turing Machine i.e The Universal Turing machine is Turing Complete. Computers that can emulate a Universal Turing Machine are called Turing Complete A Computer that is Turing Complete can emulate any other computer. copyright UEA mhf@cmp.uea.ac.uk slide 23

24 Timeline: Manchester computer developments Ferranti Mark 1 Mark 1 (Manchester University) SSEM (Manchester University) Heath Robinson - (Bletchley Park) specialised electronic machine for Cypher-breaking. Prototype for Colosus (not a universal computer). Alan Turing (studying at Cambridge) publishes a paper on computable numbers which introduces the concept known today as a Turing Machine copyright UEA mhf@cmp.uea.ac.uk slide 24

25 Colossus (Bletchley Park) Colossus was built by Tommy Flowers and colleagues at the Post Office research station. It was used to help decrypt teleprinter messages encrypted by a German Lorentz SZ40/42 cipher machine. In Colossus, the program was set on a patch panel and there was only a very limited store. Colossus was not Turing Complete copyright UEA mhf@cmp.uea.ac.uk slide 25

26 Set your clocks for 1948! copyright UEA slide 26

27 Universal Computing Machines The earliest computing machines had a fixed program; examples include Mechanical Calculators (Comptometers) Konrad Zuse s design of 1938 ENIAC In order to be reprogrammed they needed to be rewired, often completely rebuilt! The Stored-Program Computer is much more flexible an instruction set architecture (ISA) allows the computation to be expressed as a sequence of instructions (the program). the program is stored in a modifiable form (in memory). instructions are fetched from store one at a time and executed by switching networks built out of simpler Boolean logic switching circuits hence, the machine is much more flexible copyright UEA mhf@cmp.uea.ac.uk slide 27

28 Realising Boolean Functions A B F Truth Table (AND) Equivalent Switching Circuit (Lamp F ON when both A AND B are closed) A B F Truth Table (OR) Equivalent Switching Circuit Lamp F ON when A OR B is closed copyright UEA mhf@cmp.uea.ac.uk slide 28

29 1940 s Technology: Switching Elements-1 Option 1: Relays Relays (electrically operated switches) were widely used in the public telephone system A current flowing through this coil produces a magnetic field, causing the switch contacts to close. Konrad Zuse used technology like this in his calculators but the switches are slow to operate and unreliable copyright UEA mhf@cmp.uea.ac.uk slide 29

30 1940 s Technology: Switching Elements -2 Option 2: Vacuum Tubes or Thermionic Valves - widely used in domestic radio receivers 1935 Radio Set - Triode valve is a three terminal thermionic valve Diode valve is a two terminal thermionic valve anode heater grid cathode The heated filament causes a flow of electrons that are attracted to the plate and create a current. Applying a negative charge to the control grid will tend to repel some of the (also negatively charged) electrons back towards the filament: the larger the charge on the grid, the smaller the current to the plate. If an AC signal is superimposed on the DC bias of the grid, an amplified version of the AC signal appears in the plate circuit. copyright UEA mhf@cmp.uea.ac.uk slide 30

31 Components: Switching Elements -2 Triodes were used as switching (gates) and storage elements (flip-flops) copyright UEA slide 31

32 Components: Switching Elements 2 Valve Boolean logic circuits copyright UEA mhf@cmp.uea.ac.uk slide 32

33 1940 s Technology: Memory The CRT (Williams-Kilburn Tube) Freddie Williams and Tom Kilburn had both worked on Radar at TRE Malvern (Qinetic) during the war. They devised an ingenious storage device based on a Cathode Ray Tube. CRTs used in radar are refreshed every few seconds. So they rely on long persistence phosphor to maintain the image on the screen. To store data an array of. is written to the screen and positioned representing 1 and 0 bits. The data needs to be periodically refreshed (read and re-written) copyright UEA mhf@cmp.uea.ac.uk slide 33

34 Manchester SSEM ( Baby ) Work on the Mk1 started by developing a prototype called the SSEM (Small Scale Experimental Machine). 32-bit word length Serial binary arithmetic using 2's complement integers A single address format order code A random access main store of 32 words, extendable up to 8192 words A computing speed of around 1.2 milliseconds per instruction The first program to run successfully, on June 21st 1948, was to determine the highest factor of a number. copyright UEA mhf@cmp.uea.ac.uk slide 34

35 First Program: Euclid s Algorithm Determines highest common factor (hcf) of two numbers a & b The algorithm is called Euclidean because it appears in Euclid's Elements as proposition 1 of book 7. It can be useful in all sorts of situations. copyright UEA mhf@cmp.uea.ac.uk slide 35

36 The First Program copyright UEA slide 36

37 Manchester Mk1 The William s Tube CRT memory is implemented on a small CRT tube (too small for the mounting so is supported on a cardboard box) Switching circuits implemented using about 4000 valves.. The valves were very unreliable early computer users were lucky if they got more than a couple of hours continuous operation before a hardware failure! copyright UEA mhf@cmp.uea.ac.uk slide 37

38 As reported in 1948 BBC News copyright UEA slide 38

39 Instruction Format Unused Instruction Code Address (S) The Williams tube RAM stored 32 x 32 bit words (extendable to 2 13 words) 2 3 = 8 possible instructions (only 7 actually used):- A Accumulator CI Current Instruction (i.e. PC) A = - S A = A - S S = A If A < 0, CI = CI + 1 (i.e. if A negative, skip the next instruction) CI = S CI = CI + S Halt the program copyright UEA mhf@cmp.uea.ac.uk slide 39

40 The Ferranti Mark 1 In 1948 the government's chief scientist initiated a government contract with Ferranti Ltd. to make a production version of the Manchester Mark 1 "to Professor Williams' specification". The Ferranti Mark 1 was the world's first commercially available generalpurpose computer. The first machine off the production line was delivered to the University in February It was replaced in copyright UEA mhf@cmp.uea.ac.uk slide 40

41 Some data relating to the Ferranti Mk1 Overall dimensions. Two bays each 16 feet long, 8 feet high, and 4 feet wide -- and a control desk. Power consumed kilowatts Ventilation. The Electronic Equipment is continuously ventilated by means of a recirculating air system with heat exchanger connected to an external cooling unit. Number of Components. About 4,000 valves, 2,500 capacitors, 15,000 resistors, 100,000 soldered joints and 6 miles of wire. Storage capacity. High speed -- 10,000 binary digits on cathode ray tubes; equivalent to about 3,000 decimal digits. Magnetic drum ,000 binary digits; equivalent to about 15,000 twelve-digit decimal numbers or 30,000 six-digit decimal numbers. Input. Punched teleprinter tape feeding in up to 200 characters per second. Output. Punched teleprinter tape or direct printing by teleprinter. A high-speed parallel output printer is being developed. Multiplication time milliseconds Addition time milliseconds Typical times for sub-routines. Square roots and reciprocal square roots: 105 milliseconds. Cosines of angles to 11 decimal digits: 80 milliseconds. Reciprocals: 95 milliseconds. Inversion of matrix of order n x n: 0.04 n3 seconds. A matrix of order 80 x 80 is now well within the capacity of the machine. copyright UEA mhf@cmp.uea.ac.uk slide 41

42 UK Commercial Computer Production Over the period 1951 to 1959 Ferranti supplied about 25% of the (high performance) UK computer market. Competitors were Elliott Brothers (32%), Leo (16%) and English Electric (15%) Ferranti sold its computer manufacturing business to International Computers and Tabulators (ICT) in ICT and in 1968 ICT merged with Elliott and Leo to become ICL (International Computers Ltd). The company is now owned by Fujitsu. Ferranti continued to build industrial and military computers at Manchester until ~1987. copyright UEA slide 42

43 The Collapse of Ferranti In 1987 Ferranti purchased International Signal and Control (ISC), a Pennsylvania based defence contractor. The company subsequently changed its name to Ferranti International plc. and restructured the combined business into the following divisions: Ferranti Computer Systems, Ferranti Defence Systems, Ferranti Dynamics, Ferranti Satcomms, Ferranti Technologies and International Signal & Control. Unknown to Ferranti, ISC's business primarily consisted of illegal arms sales started at the behest of various US clandestine organizations. On paper the company looked to be extremely profitable on sales of high-priced "above board" items, but in fact these profits were essentially non-existent. With the sale to Ferranti all illegal sales ended immediately, leaving the company with no obvious cash flow. Ferrant was forced into bankruptcy in The Sonar business still exists and the Cheadle Heath site is now merged as Thales Underwater Systems. copyright UEA mhf@cmp.uea.ac.uk slide 43

44 Recreation of the Manchester Mk 1 Celebrating 50 th Anniversary Interview with Tom Kilburn copyright UEA mhf@cmp.uea.ac.uk slide 44

45 Further Reading The Dream Machine BBC documentary and book www The Dream Machine: Exploring the Computer Age Author(s) Jon Palfreman and Doron Swade Publisher BBC Books London, UK Copyright 1991 Pages 208 ISBN Documents the recreation of the Manchester SSEM copyright UEA slide 45

46 The End Questions? copyright UEA slide 46