Advent of Computing - Episode 6.5 - Edge-Notched

Episode Date: June 23, 2019

In this byte-sized episode we look at edge-notched cards. A punch card adjacent technology with a strange connection to the early internet.

How would you deal with having to sort and filter a large set of data without using a computer, a calculator, or anything else electronic? For a lot of people, myself included, this seems like an insurmountable task. But I can give you a hint to the solution. All the data that you have is stored on a stack of paper cards. You also have two special tools with you, a hole punch and a long metal needle. Still stumped? Well, it turns out that there is a solution and it dates back as far as the late 1800s. Let me explain to you the power of the edge-notched card. Welcome back to Advent of Computing. I'm your host, Sean Haas. This episode is another bite-sized piece, as well as a sort of follow-up to an earlier episode. Now, way back in episode

one, I shared the story of the punched card, a now far obsolete technology that was able to store generic data on stacks of punched card stock. Well, today I want to go back and add in a quick footnote to that story. So let's dive into a fast discussion of the edge-notched card, a technology from well over 100 years ago that's a close cousin of the punch card. So first off, what does one of these cards look like and what exactly even is this technology? Well, turns out that's sort of hard to pin down. There was never really an agreed upon standard for the edge-notched card,

so there's a lot of competing examples you can dig up. But generally speaking, they're made out of stiff cardstock with a series of notches and holes cut out around each side. Each notch would represent some kind of binary data point, basically just a long series of yes-no questions trailed around the perimeter of a piece of paper. But cutting a certain pattern of notches along the card edge would allow you to encode a small amount of data. Some of the earliest examples, circa 1896 or so, only have notches cut out of the bottom edge. Now, these cards would be used in conjunction with a special type of filing cabinet. The cabinet would have rods or other notches inserted in the bottom that corresponded to a certain series of notches on the card. This way, only cards with the correct cut would be able to fit into the cabinet.

This allowed for a very rudimentary type of filtering. Now, later examples are much more interesting, at least in my opinion. I haven't been able to pin down an exact date, but starting sometime in the mid or early 1900s, cards started appearing with notches on all four sides. These worked in a different way from earlier cards and allowed for more complicated operations. Each card would start off with a series of holes and notches punched out of the entire perimeter of the card. To select a set of cards from a deck, an operator would insert a long metal rod into one of the keyholes and then pull up. Any cards

with a notch in the selected category would remain in the deck while any with a hole in that category would be pulled up on the metal rod. Maybe a quick example will make more sense. Let's say I'm running a company, Sean Incorporated, and my company sells widgets. Now, I need a way to keep track of all my invoices as a set of edge-notched cards. Of course, the most important data point for Sean Inc. is if the widgets are paid for or not. So in this scheme, I'm setting a notch to be paid and a hole to be unpaid. So in this scheme, I'm setting a notch to be paid and a hole to be unpaid. Now, if I want to see who owes me for widgets, I thread my needle through the unpaid hole and lift up. With one operation, I can easily separate the paid from unpaid invoices.

With this example, I'd now be holding a stack of unpaid widget invoices in my hand. And that's really the basic idea of edge-notched cards. Now what I find impressive about this type of data storage is that with a simple set of instruments, you can not only filter, but also perform logical and and or operations, or even sort binary numbers encoded as simple notches and holes. So where were edge-notched cards used? One prominent place was in libraries. It turns out that card catalogs of books could easily be adapted to use edge-notched systems. These cards are also commonly used in schools for keeping student records. But there's another strange place that Edge Notch appears in.

In 1962, Doug Engelbart published the paper Augmenting Human Intellect. This was a pivotal examination of how computer-human interfaces could be designed to be more effective and how this would change not only computers, but also humanity. This work would eventually lead to the first graphical user interfaces, effective, and how this would change not only computers, but also humanity. This work would eventually lead to the first graphical user interfaces, as well as many other amazing advances in computing. If you want to hear more on that story, check out episode 2 of this podcast, where I go more in-depth on the story of Doug Engelbart. Now, buried deep in that 1962 paper, Doug describes how he uses edge-notched cards to keep track of his research and of papers he's reading. But beyond just his personal use of the edge-notch system, in the space of only a few paragraphs,

he lays out how one could create a database where each card would contain a single topic or idea, and each topic could be linked to others through a serial number encoded in edge notch on the top of the cards. Now think about this for a second. Pages of information with links to other pages. This is a really early description of the internet. In a sense, this is a proto-hypertext. But it's implemented with a set of punched cardstock pages and a long metal needle. That's all I have for today.

If you liked this episode, then consider going back to the archive and giving a listen to episode 1. In that episode, I describe other historic uses of cardstock for data storage. Thanks for listening to Advent of Computing. In that episode, I describe other historic uses of cardstock for data storage. Thanks for listening to Advent of Computing. I'll be back in a week's time with another full-length episode. In the meantime, consider sharing this podcast with a friend. You can also rate and review on iTunes. If you have any comments or suggestions for a future episode, feel free to shoot me a tweet.

I'm at Advent of Comp on Twitter. And as always, have a great rest of your day.