On Thu, 2008-04-03 at 06:30 +1000, Michael D. Setzer II wrote:
On 2 Apr 2008 at 18:09, Matthew Saltzman wrote:
> On Wed, 2008-04-02 at 09:48 -0700, Les wrote:
> > On my punch cards they did. Every card had a number sequential to the
> > sequence. The punch we used inserted them automatically. Well, the
> > programming card did. The reference number used for calls may have been
> > different, but I don't remember it.
>
> Those weren't line numbers per se (in the sense that BASIC had line
> numbers, for example). In FORTRAN, an 80-column card was divided into
> fields:
>
> Column 1: 'C' indicated a comment line, ' ' a code line.
>
Columnt 1-5: is for line numbers and on many compilers they had to be right
aligned.
OK, but these are the statement labels described below, not line numbers
per se.
> Column 2-6: Statement label numbers. These were arbitrary numbers used
> as targets for FORMAT, GOTO and "computed GOTO" (now *that* was a flow
> control concept!), and DO statements. These did not have to obey any
> ordering rules. There was no concept of an if-else block or a while
> loop with a logical test, so flow control was handled by GOTOs of some
> variety. Targeted statements were usually CONTINUE statements (no-ops),
> because there was some ambiguity regarding when the targeted statement
> was actually executed, and because it made reorganizing the flow a bit
> easier (especially with punchcards[1]).
>
Column 6: Was used for continuing information from the previous card.
Generally putting a 1 in column 6 for the first continuation line, and 2, and so
on, but most didn't care. COBOL uses Column 7 for this, and uses a hyphen
if splitting a word or quoted text.
Damn, forgot the continuation character.
> Column 7-72: Code.
>
> Column 73-80: Ignored. Intended to be used for sequence numbers so you
> could sort the cards down in order if somebody dropped the deck. The
> numbers could be anything really, for example a three-letter alpha code
> identifying the deck and a four-digit sequence number.
>
> (Somebody is bound to correct me on the actual column numbers, now...)
Thanks for the corrections. I wasn't near my FORTRAN Coloring Book
(Roger Kaufman, Cambridge, Massachusetts and London England, The MIT
Press, 1978. 285 pp., paperback ISBN 0 262 61026 4,
http://www.seas.gwu.edu/~kaufman1/FortranColoringBook/ColoringBkCover.html) when I wrote
that.
--
Matthew Saltzman
Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs