Begin by grabbing the code. Unzip it in your Arduino folder, then open it with the Arduino IDE.
Under Tools, there are a number of selections you have to make:
- For board, choose "Adafruit Feather DVI"
- For optimization, choose "Optimize even more (-O3)"
- For flash speed choose "W25Q080 QSPI /4"
- For USB stack choose "Adafruit TinyUSB"
Booting Up
Now, plug your Adafruit Feather DVI in to your computer with a USB cable while holding down the BOOT button on the Feather to enter bootloader mode. Then select "upload sketch" in Arduino. Once the sketch is uploaded, plug the video out on the Feather to a monitor using a HDMI cable and reset the Feather with the reset button. You will see the RunCPM boot screen.
Using the Serial Monitor in Arduino you can run CP/M commands like "DIR". Follow the next steps so that you can use a USB keyboard connected to the Feather USB Host instead of the serial connection.
A Note about Overclocking
Generating digital video signals takes a lot of oomph! This sketch overclocks your RP2040 board to 148MHz, and increases the core voltage to 1.20V. The software documented here pushes the RP2040 microcontroller beyond its design specifications. Just like PC overclocking, there’s some risk of reduced component lifespan, though the extent (if any) can’t be precisely quantified and could vary from one chip to another. Proceed at your own discretion. It also makes CP/M emulation blisteringly fast compared to the 4MHz Z80A!
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