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Is this true?. Nothing has really changed in computer design since Von Neumann. Early Computer Architecture. Accumulator-a set of circuits to hold numeric values and do rudimentary arithmetic Register-general temporary storage - PowerPoint PPT PresentationTRANSCRIPT
Is this true?Is this true?
Nothing has really changedNothing has really changed in computer design since in computer design since Von Neumann Von Neumann
Early Computer ArchitectureEarly Computer Architecture
Accumulator-a set of Accumulator-a set of circuits to hold numeric circuits to hold numeric values and do values and do rudimentary arithmeticrudimentary arithmetic
Register-general Register-general temporary storagetemporary storage
Program counter-stored Program counter-stored location of the program location of the program instructions to be instructions to be fetched and executedfetched and executed
Word LengthWord Length Scientific work- 7 to 12 decimal digits, 30 Scientific work- 7 to 12 decimal digits, 30
to 50 bitsto 50 bits Business applications- seldom over 6 Business applications- seldom over 6
digits with 2 digits to the right of the digits with 2 digits to the right of the decimaldecimal
RCA 301RCA 301 IBM 1401-CPUIBM 1401-CPU IBM 702 IBM 702
The Labor Of ProgrammingThe Labor Of Programming
Programming has always been hardProgramming has always been hard
In the early days of large-scale In the early days of large-scale digital computers, it was labor-digital computers, it was labor-intensiveintensive
Hard to appreciate now, how much Hard to appreciate now, how much tedious work was involved thentedious work was involved then
The Early Beginnings of The Early Beginnings of SoftwareSoftware
Grace Hopper using the Grace Hopper using the Mark 1Mark 1a) coefficients of the arc tangent a) coefficients of the arc tangent seriesseriesb) lens design problemsb) lens design problems
Repetitive sequences had to Repetitive sequences had to be punched again and again be punched again and again into tapeinto tape
Compiler (A–0) “program Compiler (A–0) “program making routine”making routine” using subroutines using subroutines stored in librariesstored in libraries coder
Wish ListWish ListFloating 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
Array subscripting help
Something easier to remember than octal opcodes
Wish list Wish list continuedcontinued
Mark III – Howard AikenMark III – Howard Aiken
Ambros Speiser
Mark III had a keyboard Mark III had a keyboard to record instructions in to record instructions in ordinary algebraic ordinary algebraic notation on magnetic notation on magnetic tapetape
The Machine itself The Machine itself translated it into code translated it into code that it could executethat it could execute
This device unnecessary This device unnecessary with a stored programwith a stored program
John John Backus Backus Born in Philadelphia, 1924Born in Philadelphia, 1924
Wealthy family, bad Wealthy family, bad studentstudent
Studied chemistry some, Studied chemistry some, medicine a little, math a lotmedicine a little, math a lot
Went to work for IBM, 1949Went to work for IBM, 1949
First job - calculate First job - calculate positions of the Moon positions of the Moon
IBM model SSEC 1948IBM model SSEC 1948no memory for no memory for software storagesoftware storage
programs entered programs entered on punched paper on punched paper tapetape
thousands of thousands of electro- electro- mechanical parts mechanical parts a) unreliable unreliableb)b) slow slow
SSelective elective SSequence equence EElectronic lectronic CCalculatoralculator
SSECSSEC
Desk Control
tape
Tape Drive
IBM model SSECIBM model SSEC
IBM model IBM model SSECSSEC
Floor Plan
SpeedcodiSpeedcodingng
proto-Fortranproto-FortranFor the IBM 701For the IBM 701 fixed-pointfixed-point single-address computersingle-address computer no index registersno index registers
Speedcoding made it look like a Speedcoding made it look like a 1.1. floating-point floating-point 2.2. free-address computer free-address computer 3.3. with index registers with index registers
No more binary codeNo more binary code
It ran a lot slower because it had to do all the extra It ran a lot slower because it had to do all the extra work of simulating floating-point and index work of simulating floating-point and index registers registers
BackusBackus
FORTRAN FORTRAN FORFORmula mula TRANTRANslating Systemslating System
19541954
The first popular high-The first popular high-level programming level programming languagelanguage
FORTRANFORTRAN
A team led by John Backus at IBMA team led by John Backus at IBM
– supposed to take six months -- took two supposed to take six months -- took two yearsyears
– supposed to eliminate coding errors supposed to eliminate coding errors and debuggingand debugging
– supposed to generate efficient code, supposed to generate efficient code, comparable with hand-written code -- comparable with hand-written code -- very successful at thisvery successful at this
– closely tied to the IBM 704 architectureclosely tied to the IBM 704 architecture
COBOL COBOL 19601960CCommon ommon BBusiness usiness OOriented riented
LLanguageanguage
Produced by a committee:Produced by a committee:
Selden & Tierney - IBM Selden & Tierney - IBM Bromberg & Discount - RCABromberg & Discount - RCAReeves & Sammet -Reeves & Sammet -Sylvania Electric Sylvania Electric ProductsProducts
Able to use long character names that Able to use long character names that made the language look like ordinary made the language look like ordinary English English
COBOLCOBOL
FORTRANFORTRANIf A > BIf A > B
COBOLCOBOLIF EMPLOYEE-HOURS IS GREATER IF EMPLOYEE-HOURS IS GREATER
THAN MAXIMUM THAN MAXIMUM
COBOLCOBOL promoted by the US Department promoted by the US Department
of Defenseof Defense
for simple computations on large for simple computations on large amounts of dataamounts of data
introduced the record structureintroduced the record structure
most widely used programming most widely used programming language during the 1960s and language during the 1960s and 1970s1970s
MulticsMultics MultMultiplexed iplexed IInformation and nformation and
CComputing omputing SServiceervice time-sharing operating system co-time-sharing operating system co-
designed by a consortium including designed by a consortium including MIT, GE and Bell LaboratoriesMIT, GE and Bell Laboratories
first major OS to run on a symmetric first major OS to run on a symmetric multiprocessormultiprocessor
provided a hierarchical file system provided a hierarchical file system with access control on individual fileswith access control on individual files
Segmented memory Segmented memory
Virtual memory Virtual memory
High-level language implementation High-level language implementation
Shared memory multiprocessor Shared memory multiprocessor
Multi-language support Multi-language support
Relational database Relational database
Security Security
Multics Multics featuresfeatures
MulticMulticss On-line reconfiguration On-line reconfiguration
Software engineeringSoftware engineering written in PL/Iwritten in PL/IHoneywell commercialized MulticsHoneywell commercialized Multics
in 1972 in 1972
3 Multicians in 19783 Multicians in 1978
Myths about MulticsMyths about Multics Myth: Multics failed in 1969 when Bell Labs quit. Myth: Multics failed in 1969 when Bell Labs quit.
Multics survivedMultics survived. .
Myth: Multics failed. Myth: Multics failed. Multics met its goals.Multics met its goals.
Myth: Unix was operational before Multics. Myth: Unix was operational before Multics. False.False.
Myth: Multics was big and slow. Myth: Multics was big and slow. True at first.True at first.
Myth: Multics was vastly expensive. Myth: Multics was vastly expensive. You get You get what you pay for.what you pay for.
Myth: Ken Thompson wrote Multics. Myth: Ken Thompson wrote Multics. Ken was Ken was one of many. one of many.
More Myths about More Myths about MulticsMultics
Myth: Multics was built by the waterfall method Myth: Multics was built by the waterfall method Closer to spiral method.Closer to spiral method.
Myth: Multics was closed source Myth: Multics was closed source It was shipped It was shipped with source for many years.with source for many years.
Myth: Multics was designed with military Myth: Multics was designed with military security in mind. security in mind. Separate project.Separate project.
Myth: You had to give a password to log out. Myth: You had to give a password to log out. User app, terminal locker.User app, terminal locker.
Myth: Multics error messages were in Latin. Myth: Multics error messages were in Latin. One One was.was.
UnixUnix (first UNICS)(first UNICS) Bell LabsBell Labs
Developed on Digital Developed on Digital Equipment Corp. PDP – Equipment Corp. PDP – 7 and then PDP – 117 and then PDP – 11
Added a text formatting Added a text formatting program called “roff” program called “roff” and a text editor written and a text editor written in assembly codein assembly code
In 1973, re-written in In 1973, re-written in the C programming the C programming language language
Ken Thompson & Dennis Ritchie
C Developed in early 1970’sDeveloped in early 1970’s
Low-level minimalist Low-level minimalist standardized programming standardized programming languagelanguage
Efficient, popular Efficient, popular programming language for programming language for writing system softwarewriting system software
Ken Thompson
Dennis Ritchie
CCeasier to write large programs with easier to write large programs with
fewer errors in the procedural fewer errors in the procedural programming paradigmprogramming paradigm
Compilers, libraries, and interpreters Compilers, libraries, and interpreters of other higher-level languages are of other higher-level languages are often implemented in C often implemented in C
Two failed languagesTwo failed languages
Algol-68Algol-68 From Algol-60From Algol-60 Too complexToo complex Hard to understandHard to understand Lead to PascalLead to Pascal
PL/IPL/I To replace FORTRAN and To replace FORTRAN and
COBOLCOBOL Complexity overwhelmed Complexity overwhelmed
its advantages its advantages Release date killed itRelease date killed it
The Birth of Computer ScienceThe Birth of Computer Science
First taught in: 1) Mathematics 2) Electrical Engineering
StanfordStanford
PerduePerdue
Computer ScientistsComputer Scientists
Who Who areare these guys ! ? these guys ! ?