Real Old School Programming (was: Re: Where to buy a Selectric?)

[Chuck Guzis]

On 12/30/2005 at 10:11 PM Andy Holt wrote:

>Nearly correct - C for comment went in column 1.

Quite right--another dropped mental bit!  Column 1 was used for some
dialects of pre-FORTRAN 4 for other things too.  On the 7090 running FMS
II, a "D" would get you double precision and "B" would result in a boolean
evaluation.  Did 'I' result in complex arithmetic?  I can't recall.

>Column 6 was for continuation - anything other than a blank or zero in
this
>column appended the contents of columns 7-72 to the previous card image
for
>the compiler.
>You were allowed 19 continuation cards in Fortran 4 tho' even a very
>complex FORMAT statement rarely got that far.

Yet that 19 card limit was one of the most common "extensions" of FORTRAN
compilers.  Many set limits that were much higher.   IIRC, almost any
character in column 6 would be taken a continuation, except for '0'.  The
custom was to punch a 1 for the first continuation, 2 for the second
continuation and so on--a zero in column 6 of the first card let you know
that continuation cards followed.

Cheers,
Chuck