Friday Finds: Mysterious Magnetic Media

What’s black, magnetic, floppy, and about thirty-five years old?

While processing a collection, an archivist came across three mysterious objects in a folder from 1976. As suggested by the IBM label, however, these seven-by-three-inch disks seemed to be some kind of computer media. Web searches for various permutations of floppy disk, IBM magnetic media (, and magnetic punched card yielded no results. The archivist then canvassed coworkers, computer systems analysts, and people who were working during the 1970s. Although some valiant and confident guesses were given, none could be confirmed.

Next stop in the identification process was a quick e-mail to the Computer History Museum in Mountain View, California. Paula Jabloner, director of Collections, blithely answered, “Magnetic Card for a typewriter, see the IBM history page,” and there, indeed, was a description of the IBM Magnetic Tape Selectric Typewriter, introduced in 1969. By 1973, these cards were able to hold up to eight thousand characters and could be inserted into a separate mainframe. An additional link ( shows a picture of the magnetic typewriter tape in all its glory.

Now that we know these are magnetic typewriter cards, how do we read the data stored on them? Unfortunately, neither the Computer History Museum nor the Hoover Archives has a Selectric or Mag Card typewriter. Perhaps you can locate one in a basement or attic?