Is this true?

2. Is this true? Nothing has really changed in computer design since Von Neumann

3. Early Computer Architecture • Accumulator-a set of circuits to hold numeric values and do rudimentary arithmetic • Register-general temporary storage • Program counter-stored location of the program instructions to be fetched and executed

4. Word Length • Scientific work- 7 to 12 decimal digits, 30 to 50 bits • Business applications- seldom over 6 digits with 2 digits to the right of the decimal RCA 301 IBM 1401-CPU IBM 702

5. The Labor Of Programming • Programming has always been hard • In the early days of large-scale digital computers, it was labor-intensive • Hard to appreciate now, how much tedious work was involved then

6. The Early Beginnings of Software • Grace Hopper using the Mark 1a) coefficients of the arc tangent seriesb) lens design problems • Repetitive sequences had to be punched again and again into tape • Compiler (A–0) “program making routine”using subroutines stored in libraries coder

7. Wish List • Floating point: coders had to keep track of the exponent manually (Babylonian style) • Relative addressing: coders kept notebooks of subroutines, but the codes had to be adjusted by hand for the absolute addresses

8. Wish list continued • Array subscripting help • Something easier to remember than octal opcodes

9. Mark III – Howard Aiken • Mark III had a keyboard to record instructions in ordinary algebraic notation on magnetic tape • The Machine itself translated it into code that it could execute • This device unnecessary with a stored program Ambros Speiser

10. John Backus • Born in Philadelphia, 1924 • Wealthy family, bad student • Studied chemistry some, medicine a little, math a lot • Went to work for IBM, 1949 • First job - calculate positions of the Moon

11. IBM model SSEC 1948 • no memory for software storage • programs entered on punched paper tape • thousands of electro- mechanical parts a) unreliableb) slow Selective Sequence Electronic Calculator

12. SSEC tape Desk Control Tape Drive

13. IBM model SSEC

14. Floor Plan IBM model SSEC

15. Speedcodingproto-Fortran Backus For the IBM 701 • fixed-point • single-address computer • no index registers Speedcoding made it look like a 1. floating-point2. free-address computer 3. with index registers No more binary code It ran a lot slower because it had to do all the extra work of simulating floating-point and index registers

16. FORTRAN FORmula TRANslating System1954 The first popular high-level programming language

17. FORTRAN A team led by John Backus at IBM • supposed to take six months -- took two years • supposed to eliminate coding errors and debugging • supposed to generate efficient code, comparable with hand-written code -- very successful at this • closely tied to the IBM 704 architecture

18. COBOL 1960Common Business Oriented Language Produced by a committee: Selden & Tierney - IBM Bromberg & Discount - RCAReeves & Sammet -Sylvania Electric Products Able to use long character names that made the language look like ordinary English

19. COBOL FORTRAN If A > B COBOL IF EMPLOYEE-HOURS IS GREATER THAN MAXIMUM

20. COBOL • promoted by the US Department of Defense • for simple computations on large amounts of data • introduced the record structure • most widely used programming language during the 1960s and 1970s

22. MulticsMultiplexed Information and Computing Service • time-sharing operating system co-designed by a consortium including MIT, GE and Bell Laboratories • first major OS to run on a symmetric multiprocessor • provided a hierarchical file system with access control on individual files

23. Segmented memory • Virtual memory • High-level language implementation • Shared memory multiprocessor • Multi-language support • Relational database • Security Multics features

24. Multics • On-line reconfiguration • Software engineering • written in PL/I • Honeywell commercialized Multics in 1972 3 Multicians in 1978

25. Myths about Multics • Myth: Multics failed in 1969 when Bell Labs quit. Multics survived. • Myth: Multics failed. Multics met its goals. • Myth: Unix was operational before Multics. False. • Myth: Multics was big and slow. True at first. • Myth: Multics was vastly expensive. You get what you pay for. • Myth: Ken Thompson wrote Multics. Ken was one of many.

26. More Myths about Multics • Myth: Multics was built by the waterfall method Closer to spiral method. • Myth: Multics was closed source It was shipped with source for many years. • Myth: Multics was designed with military security in mind. Separate project. • Myth: You had to give a password to log out. User app, terminal locker. • Myth: Multics error messages were in Latin. One was.

27. Unix(first UNICS) • Bell Labs • Developed on Digital Equipment Corp. PDP – 7 and then PDP – 11 • Added a text formatting program called “roff” and a text editor written in assembly code • In 1973, re-written in the C programming language  Ken Thompson & Dennis Ritchie 

28. C • Developed in early 1970’s • Low-level minimalist standardized programming language • Efficient, popular programming language for writing system software Ken Thompson Dennis Ritchie

29. C • easier to write large programs with fewer errors in the procedural programming paradigm • Compilers, libraries, and interpreters of other higher-level languages are often implemented in C

30. Algol-68 From Algol-60 Too complex Hard to understand Lead to Pascal PL/I To replace FORTRAN and COBOL Complexity overwhelmed its advantages Release date killed it Two failed languages

31. The Birth of Computer Science First taught in: 1) Mathematics 2) Electrical Engineering

32. Stanford

33. Perdue

34. Computer Scientists Who are these guys ! ?