Advancing Technologies: From Slide Rule to FORTRAN

The Introduction to Engineering class provided me with another gem: the slide rule.  Imagine a calculator on a stick. This ancient tool of the engineering trade used to multiply and divide is actually an amazing masterpiece.

First designed in the 1600’s, it evolved through the centuries until the mid 1970’s saw its demise with the advent of the personal calculator. Engineers and scientists relied on the many versions of this handy calculator for their design work. Precise to three digits, that seemed to be enough for the designers of the Apollo space program, the Empire State building, and the Golden Gate Bridge. Yep, who needs a computer?

Your Basic Slide Rule

While Texas Instruments and Hewlett Packard enticed us with magic boxes that could, with a push of a few buttons, calculate pi down to 10 decimal digits, my Intro professor tried to convince us of the need to learn the primeval art of the slide rule.

The new fangled calculators were not only expensive, over a hundred dollars for a model that performed the basic functions of addition, subtraction, multiplication and division; they also required a battery and AC adapter.  What if the electricity went out, he pondered, then how would we do our calculations? Would the design world stop? Would progress, as we knew it, halt? Say it isn’t so!

And with that, he dove into the mysteries of the slide rule and dragged my class of twenty or so along with him.

I own two slide rules. One was my father’s. He worked as a draftsman for various pipeline and aerospace programs, including the Apollo space program. The other I purchased for my required class; my dad still used his at work. Eventually it became mine. And to think my sister complained about wearing my hand-me-downs. Never fear, I didn’t wear them on a holster as some of the really geeky guys did, along with their pocket protector. My slide rule resided tucked away, inconspicuous, until I had to produce it during class.

It really wasn’t hard to learn the slide rule, but when you have access to an overpriced mini-computer, it was like using stone tablets and chisels to compose a blog. If the power’s out for more than a few hours, I think there will be bigger problems to worry about than figuring out the diameter of a column to support a three-story building.

A recent search for information about the slide rule found the International Slide Rule Museum,, a place for aficionados with an appreciation for the slide rule and ensuring its place in history. If this blog entry isn’t enough to satisfy your slide rule appetite, then this website will.

Confident in my newfound abilities to design with only paper, pencil and slide rule, my next learning experience involved a required course in FORTRAN computer programming. FORTRAN is an acronym derived from “IBM Mathematical Formula Translating System” and, yes, it was originally developed by IBM, formerly known as ‘big blue’ before they lost the computer bubble in the 1980’s.

The objective of this class, as I remember, taught me how to write simple programs to calculate basic equations. Today’s PCs are great, but I don’t think you’ve lived until you’ve used a keypunch machine. Looking like a huge typewriter, blank three inch by seven-inch cards automatically fed into the return one at a time. The programming lines were typed via a keyboard and the machine in turn cut small holes into the card that the computer could read but no human understood. These simple programs only took about ten cards, or lines of code, as it is known now.

Small Version of a Keypunch Machine

The computer was housed in the basement of the math building. The computer took up most of the basement. As big as it was, it had a very slow processor.

Most of the science classes on campus required their students to learn about this fascinating piece of machinery, increasing the demand for both the keypunch machines and the computer. I soon discovered mid-afternoon was the busiest time of day in the computer lab.  Results of my programming took well over two hours due to the mass demand and the slow reaction time of the computer. I begrudgingly headed out late at night through campus for faster results. Faster is relative; from midnight to two in the morning it only took one hour. Per run. One hour.

I handed my carefully typed and stacked cards to the computer geeks, the only ones authorized to feed the machine. I avoided the geeks, afraid to lock eyes with them. They seemed to be there twenty-four hours a day. It didn’t matter what time of day I went, the same geeks were there, monitoring the computer.  They scared me.

In went the cards and forever later a computer printout emerged containing a copy of the lines of code and the result. Mistyping one lousy character resulted in a voided run and the cycle of keypunch, computer, wait, printer began again.

The nightmare was not over with a good run. The printer was the last in the series of bad experiences. The output showed up on a large, striped paper seventeen inches wide perforated every eleven inches. The paper propelled through the printer using a gear that pushed the paper through holes located on either side of the sheet. Each computer user had to retrieve his or her own printout. Much to the geeks’ amusement, unless the sheets were held in just the right way, whatever way that is, it seemed to be a crap shoot, the paper tore in a thousand different ways radiating from its perforations that were supposedly put there for easy removal.  I had many printouts that also took the next sheet or part of it anyway, jamming the printer, the geeks coming over to reset the machine. Don’t look at the eyes! Is it time for breakfast yet? I hated that class.



About stemzandroses

I'm an engineer and writer with a built-in need to share my nearly 40 years of experience working in a male-dominated field with the rest of the world.
This entry was posted in Uncategorized and tagged , , , , . Bookmark the permalink.

4 Responses to Advancing Technologies: From Slide Rule to FORTRAN

  1. CE Jones says:

    Thanks. Brings back some fond memories of using the slide rule in science and math classes, the IBM “Data Processing” classes the IBM machine in college. Also, the first time I ever saw a calculator. It was a TI calculator. I worked my way through college in a grocery store. The milkman came in one day with this strange growth on his belt. It was a TI calculator in a holster. It cost him $275. That’s more than I was making in a month at that time!

    • It is really amazing what those first calculators went for back in the 70’s. I remember I bought mine at a TI office in Tulsa, they weren’t available in stores then. My basic model was only $100, but being in college and little income, it was a lot of $$.

  2. I was a project engineer for a pulp/paper company for 15 years before going into nursing. I still remember watching my father use a slide rule as an engineer in the 1970s, before he could afford the amazing TI. I loved reading your slide rule post. Consider yourself bookmarked.

    • This article stirred up a lot of memories for people and most are confessing to still owning their slide rule. I imagine our kids will flood flea markets with slide rules once we are all gone. Thanks for your comment and for the bookmark! Conni

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s