Magnetic Core Memory Plane - Small Cores - For Display For Sale
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Magnetic Core Memory Plane - Small Cores - For Display:
Before semiconductor memory replaced it, a computer's main memory was made up of magnetic cores. Each memory location was composed of a tiny ferrite bead strung on wires for addressing and to read or change the magnetic state of that bit. Early 1960s versions had large (relatively speaking) cores and were hand-assembled. This board is an example of 1970s technology (board has a date code of 7409), machine-made with very tiny cores.I bought this from a seller several years ago when I needed some core memory samples for display. Now it's time for it to find a new home with someone who has the space to properly show off this piece of computer history.
Note that this sale is for the core section ONLY from a larger board on which it was mounted and contained the interface electronics.I've included a picture of a similar item sold previously, which shows how this piece fit on. As noted on the picture that is NOT the board you will receive. The other pictures are what you get.
What I've been able to find says this was a 4K x 18-bit memory board, which means there a LOT of cores. I had originally displayed this under a magnifier so the cores were more easily seen. This listing includes a close-up of a few cores and wires, through a USB microscope at 60X magnification.
The board is 7 inches wide by 6.25 high overall. The actual core portion is 5 by 3.75 inches. Sorry to say there is an area with some missing cores, shown in more detail in one picture. Given the small core size the defective area isn't blindingly obvious without magnification. That's how it was when I purchased this. There are cores on both sides, and I have never had the cover off the side with the Dataram Corporation sticker. As pictured, the warranty seal is still intact. I have no reason to think there are any bad cores on that side as they've been protected.
Shipping is by USPS Priority Mail, so this can be in your hands in just a few days. Feel free to contact me with any questions, and thanks for looking!