5 Jan
2012
5 Jan
'12
11:23 p.m.
On 5 Jan 2012 at 22:52, Rich Alderson wrote:
From: Fred Cisin
Sent: Wednesday, January 04, 2012 7:54 PM
> Think of it as an old-style version of BASIC. WRITE is like
> PRINTUSING, with FORMAT being where you specify the print pattern.
> Any variable whose name starts with the letters I J K L M or N
> (alphabetic letters between I and N (which is the start of
> "INteger")) is assumed to be an int, unless you tell it otherwise.
> Many brands of it require giving a line number to every line. CALL
> instead of GOSUB, . . . There are so few differences that you can
> list them!
FORTRAN does not have line numbers, it has *statement*
numbers, and
they need not be sequential, nor increasing from beginning of program
to end. Certain constructs, such as the DO loop and the FORMAT-driven
I/O statements, *require* statement numbers:
DO 10 I=1,10
WRITE (7,100) I
10 CONTINUE
100 FORMAT (1X,1I3)
FORTRAN has restrictions about what you can and can't do in a DO
loop. For example, you are not permitted to change the value of the
index variable during the course of a loop. At the normal (rather
than a premature exit via GO TO) end, the value of the index variable
is undefined. Unlike BASIC, the terminal statement of a DO loop does
not specify which loop of a nested DO is being terminated--in fact,
the same terminal statement may be used for all members of a nested
DO. There are other restrictions about transfer in and out of DOs.
The devil's in the details and FORTRAN has a considerable number of
them.
There were other "simplified FORTRANs'' running around at about the
same time as K&K were working on BASIC. For example, there was
IITRAN (Illinois Institute of Technology), primarily intended for
students on TTYs, first implemented on a 7040 in 1964.
Here's a sample:
http://99-bottles-of-beer.net/language-iitran-1899.html
Note that the "==" is the assignment and "=" is the relational
operator.
And there were other "simplified FORTRANs", such as PUFFT, an ultra-
forgiving compile-and-go FORTRAN from Purdue, Waterloo had WATFOR,
and so forth.
All mostly because machine time was expensive and students
appreciated instant gratification.
--Chuck