Magnetic Core Memory supposedly from a Litton (now Northrop Grumman Navigation Systems Division) navigation system. The only reference that I can find to this is in the Commerce Business Daily Issue of April 11, 1997 PSA#1822 It is 2.75 by 5.00 inches. Four blocks of 4,096 cores, two on each side, for a total of 16,384 cores, or a whopping 2KB. That's almost enough to store just the text on this page. I won't bother describing how it works, there are lots of descriptions, discussions, and photos that do that. Before you leave here, check out the the IBM 737 Magnetic Core Storage Unit. Their photos aren't as cool as mine are, though. Below you can see the individual cores (the shiny black things) and the wires (the red things) used to access, read and write each core. There appear to be four wires through each core. Click on the photo for a larger version. The "71" in the photo below is from the date on a penny as seen through a microscope at 50x. Keep reading to see why it's here. With the same microscope, we see one core element on the edge of one block of 4,096 cores. It's slightly twisted and gives us a nice side view. Note the right edge of the photo -- that's the core memory without magnification from the microscope, and only 4x from the camera. Four core elements. Now it looks like they have only three wires. About the photos: All photos taken using a Canon G3 at maximum resolution of 4.0 megapixels, using the highest quality setting. The second photo from the top used 4x zoom on the camera plus a "Kodak Ektanar 102mm Projection Lens" from a slide projector placed in front of the lens (Hey, it worked!). The last three were taken by replacing half of the eyepiece in the microscope with the camera on a tripod. Using no zoom on the camera gave the widest view, but using 4x zoom gave the largest image. These are full-size (not cropped) at 4x zoom. All photos copyright 2004 Brian Walenz. Use them, print them, share them, just don't claim you took them.