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  Quintus Quadratus
  Lovebyte 2023
  Mecrisp & Fuz

  Matthias Koch
  m-atthias@users.sf.net
  http://mecrisp.sourceforge.net/

  Robert Clausecker <fuz@fuz.su>
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The classic "Munching Square" running in 32 bytes on a RISC-V microcontroller,
using two DAC channels for vector graphics on an analog oscilloscope.

Quintus Quadratus is designed for GD32VF103 microcontrollers and
draws vector graphics on an analog oscilloscope in XY mode
connected to

   GND and the two DAC channels on pins
   PA4 (vertical) and
   PA5 (horizontal).

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  Design ideas:
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This is a RISC-V port of the classic "Munching Square", as no architecture
in demoscene can be considered complete without this timeless effect.

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  How to run:
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If you have connected your

Longan Nano board to
             a USB-serial cable with 3.3V logic levels

3V3 or 5V -- VCC (measure the voltage present here)
R0        -- TXD
T0        -- RXD
GND       -- GND

you can flash it if you first

* Press and hold BOOT0 button
* Press and release Reset button
* Release BOOT0 button

and then execute

stm32loader -e -w -v -p /dev/ttyUSB0 quintus-quadratus.bin

on your host machine.

Press and release Reset button to start demo.

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  Credits:
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* Inspiration:

  Munching Square, classic PDP-1 demo

* Saved two bytes for success:

  Robert Clausecker (Fuz)
