Old Fortran Question

[JohnNichols]

SENSE LIGHT 1 

IN the original Fortran there is the command SENSE LIGHT 1 to 5.  

So if you are looking for the flow of the program these lights provide a simple method.  Of course now we debug or use write statements.  

When did the SENSE LIGHT commands leave Fortran?

[Steve_Lionel · Accepted solution]

SENSE did not make it into FORTRAN IV (FORTRAN 66), the first standard. It was in the original IBM compilers for the 704/7090, etc.

[JohnNichols]

It was a pretty good idea, you could get your program to output morse code on the lights and follow without all those blasted write Statements. 

Bring back the sense.

[mecej4]

A monochrome sense light represents a single bit, so three sense lights gave you the equivalent of a WRITE with an I/O list that could be no longer than three bits.

Since there was no timesharing on those old monsters, a normal user (not the operator) would never see a sense light that was on for a few moments several hours earlier. 

Similarly for sense switches as input devices to control execution.

[cryptogram]

Early versions of Fortran sometimes had odd, and sometimes machine specific, keywords.

Fortran on the 1960's vintage IBM 1620, had device specific I/O statements like ACCEPT for the keyboard, PUNCH to write to a card on the card reader/punch.   The machine included 4 toggle switches whose status you could test in a Fortran II program using a special IF statement that included  SENSE SWITCH in one way or another.  Seems like we used it to come up with a seed for random number generation by having a loop that incremented a variable until the user flipped one of the toggle switches.