Here is a list of the other program statements allowed in FORTRAN IV: There was only one loop statement, the DO, which could be nested:Ĭ do some calculations, I starts at zero,Ĭ increments by 3, and exits when it exceeds 10įORTRAN IV did have SUBROUTINEs and FUNCTIONs that were entered using a CALL statement and exited with a RETURN. There was an IF statement that tested for. Depending on the result the statement jumped to one of the three line numbers following the statement: The value in the statement was tested for being greater than, equal to, or less than zero. One of the interesting control structures was the arithmetic IF statement. The other data types were COMPLEX, CHARACTER, and DOUBLE PRECISION.Īrrays were declared with the DIMENSION statement: This could be overridden by explicitly typing a name: The letter I-N as the first letter implicitly meant the variable was an integer. Variable names were limited to 6 characters and had to start with a letter. A variable named XYZ was valid in that form, as X YZ, or as XY Z. I worked as an operator at SUNY at Buffalo on that CDC 6400 and loaded programs and data that spanned multiple trays of cards.Ī space, interestingly enough, was not a character. I’ve seen programmers literally cry when a card or tray dropped with cards that were not sequenced. A box of cards contained 2,000 cards and trays about 5,000.
The remainder, from 73 to 80, were not used by the compiler. The intent was to put sequence numbers in those cards so when the deck inevitably was dropped, or the card reader ate it, you could sort the cards into proper order again. A good practice was to use characters in sequence so you could tell the order of continuation.Ĭolumns 7 to 72 were for program statements. The sixth character could be anything except a ‘0’, which meant the card was a continuation of the previous card. The line number provided the destination for GOTOs. Otherwise the characters were either blank or a line number. If the first character was a ‘C’ is was a comment card. Because of my fascination with computers I’d taken a key punching and automation machines class in high school so I was all set.Ī FORTRAN card begins with a field of 5 characters.
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To be really good you had to know how to create a programming card that would let you skip through the fields on a FORTRAN card, or how to edit a card by duplicating it and holding one of the cards in place while you typed in new characters. In those days, you needed to use a key punch to create a deck of punch cards. Reducing the number of punched cards needed for a program by a factor of 20 over assembly helped considerably.
That was not the only reason it attained success. It was the C compiler of its day in that regard.
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Not only was it the first general purpose high-level language, just beating out COBOL and LISP, but its compiler optimized the code since it needed to compete head-on with assembly language. Development began in 1953 for the IBM 704 and the project reached fruition in 1957. suggested to IBM a language to replace assembly language. This is FORTRAN’s strength – scientific calculations. The programming went well and somewhere out there is a very old paper with a reference to the results it generated about the Chadakoin River flowing through Jamestown, NY. For years, this was the FORTRAN bible, commonly referred to as just “McCracken”. I still have my black “A Guide to Fortran IV Programming” by. Off I went for 6 weeks of training on one night a week. My job was with a small State of NY office and getting approval for me to attend was surprisingly easy. To help pay for it they were inviting people to attend a seminar on FORTRAN so they could use the system. The State University of New York at Buffalo had an IBM 704 but they soon upgraded to a CDC 6400.
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This was the days of big iron when the term computer meant a room full of heavily air-conditioned equipment. He needed to calculate the biological oxygen demand in streams but didn’t have any interest in programming. One of the engineers knew of my interest in computers and asked if I would like to learn FORTRAN. I learned to program FORTRAN IV in the spring of 1968 while working as an engineering technician in water resources.
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