[Keyboard] Unicomp Mini M (#12892)

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+## Unicomp Mini M with Teensy2.0++ controller & QMK Firmware
+
+### Overview
+
+#### Goals
+
+The goal of this project was to replace the stock control board of the Unicomp Mini M with a programmable one.  The Mini
+M was released by [Unicomp](https://www.pckeyboard.com) in Q1 of 2021 and is a re-release of The IBM Model M Space
+Saving Keyboard (SSK) with some enhancements.
+
+This guide strives to achieve the following:
+
+* Make completely reversable changes, or in other words, no permanent modifications to the Mini M
+* Allow full programmability of the Mini M via QMK
+* Be able to flash firmware without having to take the board apart to hit the reset button
+* Create a default keymap that works just like the stock keymap shipped from Unicomp, including the toggle-able number
+  pad
+* Support all LEDs as normal
+
+My guide will go a few steps further:
+
+* Convert the wired connection from USB-A to USB-C
+* Install a potentiometer to dim the LEDs if desired
+
+#### Credits
+
+The following resources were instrumental to the success of this project:
+
+* Model M 101/102 write-up located in `qmk_firmware/keyboards/converter/modelm`
+* [Model M Subreddit](https://modelm.reddit.com)
+* Model M Discord
+
+### Hardware
+
+##### Parts
+
+For a working Mini M with QMK *without* LEDs working, the following parts are necessary:
+
+* 1 Adafruit Perma-Proto Full Sized Breadboard.  Luckily, this board is a perfect fit for the Mini M case!
+* 1 Teensy2.0++, with headers soldered on if you can find it
+    * 2 20-row x 1 column headers, if you can't find a Teensy with headers already soldered on
+* 2 16-pin Ribbon connectors, PCB mount
+* Hookup wire.  I used 30AWG wire and while it worked, I should have used 1 gauge (or more) thicker
+* A panel mount male USB-B to female USB-C extender
+
+To get the Mini M working with LEDs, you will need:
+
+* 3 1kOhm through-hole resistors
+
+##### Tools
+
+The following were absolutely critical for the project:
+
+* Soldering iron, preferably one with a narrow tip for small connections
+* Drill, preferably a hand-held rotary tool (such as a Dremel)
+* Wire strippers/cutters
+* A sharp knife
+
+Optional, but worth having around:
+
+* Helping-hands, PCB holder, preferably both
+* Multi-meter for testing continuity of your connections
+* Hot-glue gun for mounting the USB extender to the Perma-Proto
+
+### Assembly
+
+#### Solder Teensy to the Perma-Proto
+
+1. Solder headers to Teensy
+2. Solder headers to Perma-Proto
+
+#### Solder ribbon connectors
+
+* Rows on the Perma-Proto that line up with membrane ribbons
+* Trim excess under board
+* Test continuity
+
+#### Solder in hookup wires
+
+* Ribbon connector used for the right ribbon will need hookup wire to establish connections to the Teensy
+* 12 required, 16 if you want full functionality
+
+#### Optional: Solder in resistors
+
+#### Caveat: D6 pin on the Teensy
+
+There are a few ways to mount the Teensy to the Perma-Proto board.  I chose to connect my 16 pin ribbon connector to the
+Teensy pins starting at C7 and ending at D2.  If you do this, beware that pin D6 will not work for the purposes of this
+project.  It is possible to modify it to make it so, but that is beyond the scope of this guide.
+
+Bypassing D6 is necessary if you mount your ribbon connector as I have just described.  Luckily, it is a simple process!
+First, with a sharp knife, sever the connection between your ribbon connector pin that is connected to Teensy D6 pin.  I
+would recommend doing this at the closest possible point to the Teensy on the underside of the Perma-Proto board.  Once
+that is done, use a remaining point on the Perma-Proto bus for that ribbon connection (that was previously connected to
+D6) to add a jumper wire connected to pin B7.  If you are using the firmware files provided in this repository,
+everything is already set for this configuration.
+
+### Testing
+
+### Software
+
+#### Build firmware
+
+See qmk documentation on getting your build environment working.
+
+Compile the Mini M firmware files with the default keymap.  It allows for the Mini M to be used with the same
+functionality as shipped from the manufacturer.
+
+```bash
+$ qmk compile -kb unicomp/mini_m -km default
+```
+
+While plugged in, press the reset button on your Teensy and then:
+
+```bash
+$ qmk flash -kb unicomp/mini_m -km default
+```
+
+If everything works to this point, congratulations!  You now have a programmable Mini M.  If you are using the default
+keymap, you can reset your Teensy by pressing Shift+Pause together, eliminating the need to take apart the case in order
+to do so.
+
+#### Keymaps
+
+To build your own keymap, create a new directory in `keyboards/unicomp/mini_m/keymaps/<your name>`, copy the files from
+`keyboards/unicomp/mini_m/default` into your new directory, and edit them as you wish.  When you are ready to flash your
+new keymap to the Mini M, the command will be `qmk flash -kb unicomp/mini_m -kb <your name>`.