MMCedu project - Introduction

Time ago I wrote an article (Toroid tale) about my early experience in programming.
Electronics always fascinates me, especially digging deep about how things works, so ... here we go with some magnetic core explanations/experimentation and a retro-magnetic core building project, for fun and nostalgia lane.

Toroids

Let see briefly what toroids are and how they work since they are the base of the magnetic core memory.

A toroid is a ring made with a magnetic compound, typically ferrite.
Magnetic compound means that is a material easily subject to magnetic fields and consequently, electromagnetic fields.
Differently than an ordinary piece of iron, a ferrite based material is capable to retain a magnetic field BUT also can be easily removed or changed.
In other words, if you magnetize a piece of iron, the material will retain the magnetic field for long time and will be very very hard to change or remove it.
The ferrite will easily lose the magnetic field or change it if another magnetic field is applied but it will easily retain the magnetic field if absence of external stimuli.

So if we take a toroid and spin some wire on it, we'll be able to magnetize the toroid in two different ways, depending the current and polarity we apply to the coil.
The same if we just have a wire passing through the ferrite hole and the toroid is small enough to don't require much current (and thus magnetic field). If the current in the wire is enough, the electromagnetic fields will magnetize the toroid. Depending the direction of the current, the toroid will be magnetized clockwise or counterclockwise.

Toroid memory

So we have a component (toroid) capable to retain a magnetic field and this magnetic field can exists in two "flavor". i.e. the toroid can be magnetized in two ways, retaining this magnetization until a different one is applied.
This allow to have the toroid act as memory,
Each bit (acronym from Binary digIT) can be stored in one toroid.
8 toroids are 1 Byte, 16 a Word, etc.

A retro magnetic core circuit

Jussi Kilpelainen, a Finnic guy, designed an Arduino hat kit to control a small magnetic memory (32 bit) and I decided to buy and build this kit, expanding it little bit for fun (and to have something to talk when somebody come to visit).
The kit has a quite extensive documentation so I'm not repeating what is in there.

However my goal is to expand little bit the kit adding a vintage I/O unit in order to have the unit self sufficient and not relaying on a terminal to see what is going on.

So for the project is needed the magnetic core memory kit, an Arduino, a bunch of pushbuttons with LEDs, or just pushbuttons and LEDs, other normal pushbuttons and some kind of I/O extension in order to interface the LED and pushbuttons.

The hat of the hat

The I/O unit will be piggy backed on the Memory core kit, with the purpose to read and write the content of the memory.
So we'll have a pushbutton to reset, one to read, one to write, 32 LED representing the content of the memory and 8 pushbuttons to set the content to be written in the memory.

Basically I'm trying to reproduce more or less, the bootstrap system of ancient computer (like the HP 2000A) as input for the kit.
We'll see where the wind will bring me :)

The project will be discussed in different articles.
For now I'm working to design the keyboard and waiting for the arrival of the kit from Finland.