interesting Univac ad from 1956

[rprosperi]

(06-05-2014 10:40 PM)Don Shepherd Wrote:  I came across this ad the other day on our favorite auction site, and had to get it.

Univac ad

When I wrote FORTRAN programs for the Univac 1108 in 1974, I don't recall actually checking my denominators for zero before performing a division operation, but it's good to know the Univac would have scolded me if a zero denominator was detected. But it begs the question, what would have happened then? Apparently the computer stopped and printed out that message, presumably to the operator. What would the poor operator do upon witnessing this carelessness on the part of the programmer? Called him/her (yes, there were female programmers in those days and they were darned good) at home? Nothing? Who knows. Who cares!

My own code would probably never have encountered this situation because I don't recall doing any divide operations; our programs were oriented toward updating tape files with new information, and they were not calculation-intensive. I do teach my math students today about division by zero being "undefined," but I doubt that that fact is of much interest to them.

Most good calculators give you a "DIV by 0" today. Univac mainframes did it in 1956.

Same year, I was learning Focal (the original one) and Fortran on a PDP-8. The math teacher warned us about the "dangers" of division by zero, and cautioned us to test for and handle it with some special message (who knows, perhaps he had seen the Univac Ad). Being annoying students, a couple of us decided that the special 'message' would be to rewind the DEC-TAPE (anyone here remember those?). That being in the realm of 'system programming' and therefoe impossible (in other words, he didn't know how either) we had to settle for ringing the bell on the teletype - (For i=1 to 100; Print chr$(7); next i) You get the idea...

So you can imgine how hard we worked to create data sets that would generate zero denominators. Much to the annoyance of the other math teachers.

Thanks for that Don.