Whatever happened to …


… mark sense cards?

You had to know that this would be a natural followup to last week’s post about the Hollerith Code and punched computer cards.

Happily, as a result of these cards, I can say that my class (and many other computer science classes) were 1:1 before it became cool.  (or even contemplated)

Those two keypunch machines I had access to were awesome – when they worked.  But, they worked non-stop it seemed and repairs were needed periodically.  That would put things behind schedule so badly.  I had-not-so fond memories of having to extend deadlines to fairly address concerns about getting programs keyed in and run/debugged in a timely manner.

This was all about to change when we found “mark sense” cards.  If memory serves me correctly, that was a trade mark term for a general class of cards called optical marked cards.

Picture Credit:  Douglas W. Jones, University of Iowa Computer Science Department.  Retrieved February 11, 2017.
 http://homepage.cs.uiowa.edu/~jones/cards/collection/ibm40904.jpg

The key to success was a dark marking pencil and a great deal of care to code the bubbles on the card.

As you can see from above, these cards had their own code.  Some of the characters were easy; you just filled in the bubble.  Others were a little more challenging; you had to code the two bubbles surrounding the character.  If you look at the left side, you’ll see that there were also special bubbles for commands, statement numbers, comments, or continuation cards.  Continuation came into its own with these cards.  Unlike the punched card which allowed 80 characters, there was a pretty severe limit on characters here.

By today’s standards, meaningful variable names weren’t all that popular.  They took longer to code and calculations often resulted in continuation cards.  Darn, my class could be expensive.

The nice thing about teaching was that it was possible to have an entire class coding their own projects at once.  No more sign up lists or computer room supervision before/after schools or during lunch.  Plus, students were able to write their programs at home!

Of course, in education, we know that everything has a challenge and this was no exception.  It wasn’t necessarily cool to have to carry pencils around.  Students had pens and markers for everything.  A common question was “Sir, can I borrow a pencil?”  I also fell out of favour with the art teacher who noticed that students going from his class to mine would often bring their sketching pencils!

I learned quickly that I needed to order boxes of pencils during bulk order time but more often than not found me buying my own for class at an office supply store, or picking them up from the parking lots at golf courses.  (true story)

And, you had to be perfect or close to it when coding.  “Debugging” had a new addition – it was more than just looking at computer instructions.  There were times when you’d have to hold the card up to the light to see if you could figure why the card reader couldn’t read the character.  Plus, it didn’t take more than a moment to reach across and mark someone else’s card when they weren’t looking!  Erasers really weren’t an effective solution for coding errors either.  

And yes, it still was a costly way of handling the course.  Students in Grade 10 using HYPO and Grade 11 and 12 used Fortran and both languages required lots of cards during the duration of a course.

There was no such thing as “the” card either.  Cards came in various configurations according to design and the language needed.  Professor Jones has a great page devoted to them.

But the nice thing was that, with this technology, the course could be accelerated.  With a true 1:1, we could just focus on the task when coding.

And yet, while this wasn’t to last forever, it was somewhat nicer when we got rid of our reliance on cards and moved on with desktop computers.

Your turn.

  • Did you have the pleasure of coding with optical mark cards?  Any remembrances to share?
  • Where do you see optical cards today?  They’re probably more popular than punched cards.

Please share your thoughts via comment below.

Do you have an idea or thought that would be appropriate for my “Whatever happened to … ” series of blog posts.  They can all, by the way, be revisited here.

Please visit this Padlet and add your ideas.  I’d love for it to be an inspiration for a post!

OTR Links 02/12/2017


Posted from Diigo. The rest of my favorite links are here.