Class%202:%20History%20of%20Programming%20Languages

1
Class 2 History of Programming Languages

• FORTRAN
• LISP
• ALGOL ? SIMULA
• COBOL
• PL/1
• BASIC
• PASCAL
• C
• The so called High Level Programming Languages
  started their development in the mid 50s.

2
FORTRAN (FORmulaTRANslation)

• Fortran was design to develop scientific
  applications on the IBM 704(with punched card
  inputs) computer and the major role in its design
  was run-time efficiency.

3
Main features

• Comments
• Assignment statements that allowed mathematical
  expressions of some complexity on the
  right-hand side
• The simplicity of writing loops with the DO
  statement
• Subroutines and functions Not a new idea but it
  was implemented employing a symbolic notation
• Formats for input and output Difficult feature
  to implement on early computers
• Machine independence A fortran program could run
  on different machines

4
Main reasons for its popularity

• It made efficient use of programming time
• Easy to learn (good for non-specialist
  programmers)
• It was supported by IBM
• It simplifies INPUT/OUTPUT

5
Example of a Fortran Program

• C FORTRAN PROGRAM TO FIND MEAN OF N NUMBERS
• C AND NUMBER OF VALUES GREATER THAN MEAN
• DIMENSION A(99)
• REAL MEAN
• READ (1,5)N
• FORMAT (I2)
• READ (1,10) (A(I), I1, N)
• FORMAT (6F10.5)
• SUM 0.0
• DO 15 I1, N
• SUM SUM A(I)
• MEAN SUM/FLOAT(N)
• NUMBER 0
• DO 20 I1, N
• IF (A(I).LE.MEAN0 GOTO 20
• NUMBER NUMBER 1
• CONTINUE
• WRITE (2,250 MEAN, NUMBER
• FORMAT (8H MEAN , F10.5, 5X, 20H NUMBER OVER
  MEAN , I5)

6
Development

• The first design of Fortran was made in 1954
  (Fortran 0)
• The first implementation was developed in
  1957(Fortran I)
• A better compiler was developed in 1958 (Fortran
  II)
• After many revisions in 1962 a stable compiler
  (Fortran IV)
• First NASI standard 1966 (Fortran 66)
• After a major revision new features are added
  (Fortran 77)
• A more modern Fortran is created in 1990 (Fortran
  90)

7
FORTRAN 90

• Offers features that are common to modern
  programming languages
• Records
• Modules
• Pointers

8
FORTRAN 0 FORTRAN I(1957)
COBOL(1960) ALGOL 58 FORTRAN
II ALGOL 60 FORTRAN IV PL/1(1964)
BASIC FORTRAN 66
FORTRAN 77 FORTRAN 90
9
Referencing in FORTRAN

• All variables are local to each routine
• The local environment of a subroutine consists
  of the variables, arrays, etc. declared at the
  start of the subprogram.
• The local environment is retained between calls
  because the activation record is allocated
  statically.
• Global variables are created using the COMMON
  declaration
• COMMON /ltnamegt/ltvar or arraygt, ltvar or arraygt,
  ltvar or arraygt,

10
Example COMMON/ Globalvar/X/Y/A(20)

• program main
• real X, Y
• common /BLK/ X, Y
• statements
• stop
• End
• subroutine sub1 ( arguments)
• declarations of arguments
• real X, Y
• common /BLK/ X, Y
• statements
• return
• End
• subroutine sub2 ( arguments)
• declarations of arguments
• real X, Y
• common /BLK/ X, Y

11
Memory layout
System data and I/O buffers
Code and local data for main program
BLK (common block)
Code and local data for sub1
Code and local data for sub2
System I/O routine
12
ALGOL (ALGOrithmic Language)

• ALGOL was develop in 1958 as a committee
  effort to design a language for the description
  of computing processes in publications.
• The objectives of the language were stated as
  follows
• It should be close as possible to standard
  mathematical notation and be readable without to
  much additional explanation.
• It should be mechanically translate into machine
  code.

13
ALGOL 58 ALGOL 60 ALGOL
68 ALGOL W
SIMULA 67
PASCAL
14
Major Concepts introduced in ALGOL(1)

• Language definition a formal definition in
  Backus Naur Form (BNF) was used to define the
  syntax for the first time this led to
  syntax-directed compilers.
• ALGOL 60 was structured It was the originally
  block structured language and variables were not
  visible outside the block in which they were
  declared.
• Arrays could have variables bounds.
• Contained several structured control statements

15
Major Concepts introduced in ALGOL(2)

• Sequence S1,S2,,Sn
• Selection (IF-THEN-ELSE)
• Iteration (For I 1 step 1 until n do)
• First language to introduce recursive procedures.

16
Why ALGOL 60 did not supersede FROTRAN?

• Compilers came out approximately three years
  after Fortran.
• As it had more features than Fortran it was
  harder to learn.
• IBM customers were happy with Fortran.
• Fortran compilers were simpler to produce and
  more efficient.
• Algol 60 had not official Input/output therefore
  they left this feature to the individual
  manufacturers.

17
Example of an Algol program

• begin
• comment this program finds the mean of n numbers
  and the number of values greater than the mean
• integer n
• read(n)
• begin
• real array a1n
• integer i, number
• real sum, mean
• for i 1 step 1 until n do
• read(ai)
• sum 0.0
• for i 1 step 1 until n do
• sum sum ai
• mean sum/n
• number 0
• for i 1 step 1 until n do
• if ai gt mean then
• number number 1
• write (MEAN , mean, NUMBER OVER MEAN
  , number)

18
ALGOL 60 ALGOL W(1966) ALGOL68 SIMULA
67 BCPL PASCAL C
MODULA C ADA(83)
OBERON Eiffel(90)
ADA(95) JAVA
19

• The successor of ALGOL 60 was ALGOL W which was
  proposed by Wirth and Hoare in 1966 .
• The more important changes and additions were(1)
• Records and references allowed linked list,
  trees and graphs.
• The case statement.
• Changes which separate for and While.
• Procedures and function parameters could be
  called by values
• and by name.
• Long real and complex data type were introduced
  (complex
• arithmetic)

20
The successor of ALGOL 60 was ALGOL W which was
proposed by Wirth and Hoare in 1966 . The more
important changes and additions were(2)

• The bits data type gave low-level processing
  ability.
• Some string facilities were included.
• Assert statement were allowed and the assertion
  tested during a program run.
• Concurrent execution was implemented(B6700)

21

• The next step was ALGOL 68 which amid its
  interesting features introduced
• An economy of constructs produce a core
• language with a small number of powerful
• constructs.
• Orthogonality This was its major design goal.
• There ware no interactions between constructs
  
• when they were combined. Having determined
• how a feature worked in one situation, it
  could be
• expected to behave in a similar way in any
  other
• situation.

22

• INCLUDE RECURSION AND STACK MECHANISM

23
COBOL (Common Business Oriented Language)

• Cobol was based on the Flow-Matic
  language(1957), developed by Grace
• Hopper, and IBM's specification of its planned
  Commercial Translator.
• COBOL is essentially a data processing language
  and that is the reason why it
• differs significantly from FORTRAN and ALGOL.
• Several design principles guided the design of
  COBOL
• separate data procedures
• machine dependent statements in one place
• Naturalness (English-like form)
• ease of transcription to require media (cards at
  the time)
• effectiveness of problem structure
• ease of implementation (for compiler writers)
• physically available character set (printable)
• long data names

24
Main features

• The language is simple
• No pointers
• No user defined types
• Record data type
• Self documented

25
A COBOL program is divided in four parts

• The identification division Contains commentary
  and program documentation.
• 000100 INDENTIFICATION DIVISION.000110
  PROGRAM-ID. EXAMPLE-1-PROG.000120 AUTHOR. TIM R
  P BROWN.000130 INSTALLATION. XYZ GROUP.000140
  DATE-WRITTEN. 17/5/00.000150 DATE-COMPILED.00016
  0 SECURITY. LOCAL GROUP

26

• The environment division Contain
  machine-dependent program specifications. Thus,
  it specifies the connections between the COBOL
  program and the external data file.
• 000260 ENVIRONMENT DIVISION.000270
  CONFIGURATION SECTION.000280 SOURCE-COMPUTER.
  IBM PC.000290 OBJECT-COMPUTER. IBM PC.000300
  INPUT-OUTPUT SECTION.000310 FILE-CONTROL.000320
  SELECT INPUT-FILE ASSIGN TO 'input.dat'000330
  ORGANIZATION IS LINE SEQUENTIAL.000340 SELECT
  PRINT-FILE ASSIGN TO PRINTER.

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• The data division Gives a logical description
  of the data.
• 000800 DATA DIVISION.
• 000900 FILE SECTION.
• 001000 FD SALESPERSON-FILE.
• 001100 01 SALESPERSON-RECORD.
• 001200 05 FILLER PIC XX.
• 001300 05 SP-NUMBER PIC X(4).
• 001400 05 SP-NAME PIC X(18).
• 001500 05 FILLER PIC X(21).
• 001600 05 SP-CURRENT-SALES PIC
  9(5)V99.
• 001700 05 SP-CURRENT-RETURNS PIC 9(4)V99.
• 001800 FD REPORT-FILE.
• 001900 01 REPORT-RECORD.
• 002000 05 FILLER PIC X(10).
• 002100 05 RT-NUMBER PIC X(4).
• 002200 05 FILLER PIC X(6).
• 002300 05 RT-NAME PIC X(18).
• 002400 05 FILLER PIC X(6).
• 002500 05 RT-CURRENT-SALES PIC ZZ,ZZZ.99.

28

• The procedure division Contains the algorithms
  necessary to solve the problem.
• 000900 PROCEDURE DIVISION.000910
  CONTROL-PARAGRAPH.000920 PERFORM
  READ-DATA-FILE000930 PERFORM CALULATE-PRICES0009
  40 PERFORM PRINT-PRICE-REPORT000950 STOP RUN.

29
Example of a COBOL program(Hello world)

• 000010 IDENTIFICATION DIVISION.
• 000020 PROGRAM-ID. HELLO-WORLD-PROG.
• 000030 AUTHOR. TIMOTHY R P BROWN.
• 000040The standard Hello world program
• 000050
• 000060 ENVIRONMENT DIVISION.
• 000070
• 000080 DATA DIVISION.
• 000090 WORKING-STORAGE SECTION.
• 000100 01 TEXT-OUT PIC X(12) VALUE 'Hello
  World!'.
• 000110
• 000120 PROCEDURE DIVISION.
• 000130 MAIN-PARAGRAPH.
• 000140 DISPLAY TEXT-OUT
• 000150 STOP RUN.

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Example program 2

• 000100 ID DIVISION.
• 000200 PROGRAM-ID. ACCEPT1.
• 000300 DATA DIVISION.
• 000400 WORKING-STORAGE SECTION.
• 000500 01 WS-FIRST-NUMBER PIC 9(3).
• 000600 01 WS-SECOND-NUMBER PIC 9(3).
• 000700 01 WS-TOTAL PIC ZZZ9.
• 000800
• 000900 PROCEDURE DIVISION.
• 001000 0000-MAINLINE.
• 001100 DISPLAY 'ENTER A NUMBER '.
• 001200 ACCEPT WS-FIRST-NUMBER.
• 001300
• 001400 DISPLAY 'ANOTHER NUMBER '.
• 001500 ACCEPT WS-SECOND-NUMBER.
• 001600
• 001700 COMPUTE WS-TOTAL WS-FIRST-NUMBER
  WS-SECOND-NUMBER.
• 001800 DISPLAY 'THE TOTAL IS ',
  WS-TOTAL.

31
Example 3 Shows some basic commands

• ADD a TO b.
• ADD c TO a GIVING c.
• COMPUTE x a b c.
• SORT input-file
• ON ASCENDING KEY k
• USING inventory-file
• GIVING sorted-inventory-file
• DISPLAY totalcost.
• ACCEPT identifier.

32

COBOL continues to progress with work being done
in the Object-Oriented COBOL standard.
33
PROGRAMMING LANGUAGE 1 (PL/1)

• In the early 1960s two categories of
  programmers could be distinguished
• Scientific programmers (Fortran)
• Commercial programmers (COBOL)
• A committee at IBM developed PL/1 based in
  the following principles
• Programmers time is an important asset and
  should not be wasted.
• There is a unity in programming which current
  division between scientific and commercial
  languages did not reflect.

34
PROGRAMMING LANGUAGE 1 (PL/1) (Cont.)

• Pl/1 combined ideas from Fortran, Algol, and
  COBOL
• FORTRAN parameter passing mechanism,
  independently compiled subprograms, formatted
  input/output and COMMON blocks.
• ALGOL Block structure and structured
  statements.
• COBOL record input/output,, PICTURE type
  declaration, and heterogeneous data structures.
• From elsewhere list processing concepts,
  control structures and methods for storage
  management, exception handling by means of
  ON-conditions and concurrent execution of tasks
  (multi-tasking).

35
Example of a PL/1 program

• PROCEDURE OPTIONS (MAIN)
• / Program to find the mean of n numbers and the
  number of values greater than the mean /
• GET LIST (N)
• IF N gt 0 THEN BEGIN
• DECLARE MEAN, A(n) DECIMAL FLOAT,
• SUM DEC FLOAT INITIAL(0), NUMBER FIXED INITIAL
  (0)
• GET LIST (A)
• DO I 1 TO N
• SUM SUM A(1)
• END
• MEAN SUM/N
• DO I 1 TO N
• IF A(I) . MEAN THEN
• NUMBER NUMBER 1
• END
• PUT LIST (MEAN, MEAN, NUMBER GRATER THAN
  MEAN, NUMBER)
• END

36
BASIC (Beginners All-purpose Symbolic
Instruction Code)

• It was originally designed at Dartmouth College
  by John Kemeny and Thomas Kurtz in the mid-1960s.

37
Main Features

• Variables cannot be declared and are single
  letters.
• Variables are initialized to zero
• Easy to learn and use.
• It was interactive with commands as NEW to create
  a program or LIST, RUN, and SAVE.

38
Example of BASIC program

• 10 REM THIS IS A BASIC PROGRAM FOR FINDING THE
  MEAN
• 20 DIM A(99)
• 30 INPUT N
• 40 FOR I 1 TO N
• 50 INPUT A(I)
• 60 LET S S A(I)
• 70 NEXT I
• 80 LET M S/N
• 90 LET K 0
• 100 FOR I 1 TO N
• 110 IF A(I) lt M THEN 130
• 120 LET K K 1
• 130 NEXT I
• 140 PRINT MEAN IS, MEAN
• 150 PRINT NUMBER GREATER THAN MEAN IS, K
• 160 STOP
• 170 END

39
ALGOL ALGOL 68 ALGOL W
COBOL PL1
PASCAL ADA
40
Pascal

• It was designed by Niklaus Wirth.
• A teaching language
• The language most used in the 1970s
• Include run time environment (code, static data,
  stack ? ? heap)
• It uses the concept of static array like in
  Frotran.
• New data types(define by the user) can be built
  up from primitive data types.

41
Example of a Pascal Program

• (Pascal program for finding the mean)
• Program main (input, output)
• type intlist array 1 . . 99 of integer
• var
• a intlist
• i, n, number integer
• sum, mean real
• (main program stars here )
• begin
• number 0
• sum 0
• readln (n)
• for I 1 to n do
• begin
• readln(ai)
• sum sum ai
• end
• mean sum/n
• for I 1 to n do

42
Example for temporary expression x i (I
J) (I/J f( J ))
Outgoing results
SP
Result of I / K
Result of I J
Address of x i
Local Variables
Formal Parameter
RA
Static Link
Dynamic Link
SF
43
C

• Implemented by Dennis Ritchie in 1972
• system programming
• c 1972
• c 1989 (ANSI)
• c 1992 (ISO)

44
An Example of a C Program

• /C program for finding the mean/
• main()
• float a100, mean, sum
• / the array a has 100 elements a0, .. a99
  /
• int n, i, number
• scanf(d, n)
• for( i 0 i lt n i)
• scanf(f, a i )
• sum 0.0
• for( i 0 i lt n i)
• sum a i
• mean sum / n
• number 0
• for( i 0 i lt n i)
• if( a i gt mean)
• number
• printf( MEAN f \n, mean)
• printf(NUMBER OVER MEAN d\n, number)

No nested procedures are allowed
45
SP
Sum
Local
List4
Local
Local
List3
List2
Local
void sub(float total, int part ) int
List5 float sum
Local
List1
List0
Local
Part
Parameter
Total
Parameter
Dynamic Link
Return Address
SF
46
Run time environment for C Pascal Ada Algol Java
Object code
Static Data
Stack
Heap
47
Bibliography L.B. Wilson and R.G. Clark,
Comparative Programming Languages, 3rd edition,
Addison-Wesley, 2001. http//www.techiwarehouse.c
om/Cobol/Cobol_Tutorial.html2 Jiehong Li and
Rona Abraham notes.   M. Donald
MacLaren Exception handling in PL/I Proceedings
of an ACM conference on Language design for
reliable software Raleigh, North Carolina pp.
101 104, 1977