# **💾 Booth: Fortran (1957)** * **Creator:** John Backus (IBM) * **Design Philosophy:** "Formula Translation" — designed to make scientific, mathematical, and statistical calculations easier to translate directly into high-level programming instructions. * **Key Innovations:** First commercially successful high-level language; introduced compiler optimization, variables, structured loops (DO), and arithmetic conditionals (IF). ## **📏 Punch Cards & Column Rules** Classic Fortran (specifically Fortran 66 and Fortran 77\) relied on physical paper punch cards, meaning the placement of characters in specific columns was strictly enforced by the compiler: * **Columns 1–5:** Statement label (numeric value, optional). * **Column 6:** Continuation marker (any non-blank character indicates this line continues the previous card). * **Columns 7–72:** Statement body (the actual source code). * **Columns 73–80:** Sequence/Identification numbers (ignored by the compiler, used to reorder cards if dropped). ## **🚀 Hello, World\! (Fortran 77 Fixed Format)** C THE 'C' IN COLUMN 1 INDICATES A COMMENT LINE PROGRAM HELLO PRINT \*, 'Hello, World\!' END ## **🎨 Showpiece: Factorial Calculator** This program showcases mathematical functions, variables, and the classic arithmetic IF statement. We can express the factorial function mathematically as: ![][image1] PROGRAM FACTOR INTEGER N, RESULT, I PRINT \*, 'ENTER A POSITIVE INTEGER:' READ \*, N IF (N) 10, 20, 30 C If N \< 0 (Arithmetic IF branch 1\) 10 PRINT \*, 'FACTORIAL OF A NEGATIVE NUMBER IS UNDEFINED.' GOTO 40 C If N \== 0 (Arithmetic IF branch 2\) 20 RESULT \= 1 GOTO 35 C If N \> 0 (Arithmetic IF branch 3\) 30 RESULT \= 1 DO 32 I \= 1, N RESULT \= RESULT \* I 32 CONTINUE 35 PRINT \*, 'THE FACTORIAL IS: ', RESULT 40 STOP END [image1]: