2024-02-09 15:26:54 +01:00
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2024-02-17 11:33:14 +01:00
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<title>What is Magnetic-core memory?</title>
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<meta name="author" content="Sebastian Wendel"/>
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<body>
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2024-02-18 12:51:04 +01:00
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<main>
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<article>
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<div class="relative overflow-hidden bg-white">
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<div class="pb-80 pt-16 sm:pb-40 sm:pt-24 lg:pb-48 lg:pt-40">
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<div class="relative mx-auto max-w-7xl px-4 sm:static sm:px-6 lg:px-8">
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<div class="sm:max-w-lg">
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<h1 class="text-4xl font-bold tracking-tight text-gray-900 sm:text-6xl">What is Magnetic-core memory?</h1>
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<p class="mt-4 text-xl text-gray-500">Core memory uses
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<a href="https://en.wikipedia.org/wiki/Toroid">toroids</a>
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(rings) of a
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<a href="https://en.wikipedia.org/wiki/Hard_magnetic_material">hard
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magnetic material</a>
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(usually a
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<a href="https://en.wikipedia.org/wiki/Ferrite_(magnet)#Semi-hard_ferrites">semi-hard
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ferrite</a>). Each core stores one
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<a href="https://en.wikipedia.org/wiki/Bit">bit</a>
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of information. Two or more wires pass through each core, forming an
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X-Y array of cores. When an electrical current above a certain
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threshold is applied to the wires, the core will become magnetized.
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The core to be written is selected by powering one X and one Y wire
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to half of the required power, such that only the single core at the
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intersection is written. Depending on the direction of the currents,
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the core will pick up a clockwise or counterclockwise magnetic field,
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storing a 1 or 0.
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This writing process also causes electricity to be
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<a href="https://en.wikipedia.org/wiki/Electromagnetic_induction">induced</a>
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into nearby wires. If the new pulse being applied in the X-Y wires is
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the same as the last applied to that core, the existing field will do
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nothing, and no induction will result. If the new pulse is in the
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opposite direction, a pulse will be generated. This is normally
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picked up in a separate "sense" wire, allowing the system
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to know whether that core held a 1 or 0. As this readout process
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requires the core to be written, this process is known as
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<i>destructive
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readout</i>, and requires additional circuitry to reset the core to
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its original value if the process flipped it.
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</p>
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</div>
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<div>
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<div class="mt-10">
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<div aria-hidden="true" class="pointer-events-none lg:absolute lg:inset-y-0 lg:mx-auto lg:w-full lg:max-w-7xl">
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<div class="absolute transform sm:left-1/2 sm:top-0 sm:translate-x-8 lg:left-1/2 lg:top-1/2 lg:-translate-y-1/2 lg:translate-x-8">
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<div class="grid flex-shrink-0 grid-cols-1 ">
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<div class="h-64 w-44 overflow-hidden rounded-lg">
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<img class="h-full w-full object-cover object-center" src="./img/IMG_20240205_00.webp" alt="A Core memory Module showing the detailed structure of ferrite cores and copper wires.">
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</div>
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</div>
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2024-02-17 11:33:14 +01:00
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</div>
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</div>
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</div>
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</div>
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</div>
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</div>
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</div>
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2024-02-09 15:26:54 +01:00
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</div>
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2024-02-18 12:51:04 +01:00
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</article>
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2024-02-17 11:33:14 +01:00
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