What is it?

A microATX mainboard for the Neotron Pico - a modern 'retro' home computer, powered by the Raspberry Pi Pico and designed to run Neotron OS, a CP/M alike OS written in Rust.

It features:

• microATX form factor (240mm x 170mm)
• VGA video output, via a 12-bit (3x 4-bit) RGB R2R DAC, 75 ohm video buffer and ESD protection IC
• 16-bit stereo audio, with headphone amplifier, microphone input and stereo line input
• 12V input, with 5V switch-mode PSU rated to 3A
• Battery-back real-time clock with CMOS RAM
• Four SPI-based expansion slots
• An I/O controller providing 8 unique chip selects and 8 interrupts
• A board-management controller providing:
  • soft power control
  • TTL UART
  • two PS/2 ports and,
  • an 8 ohm PC-speaker style output
• A fully open-source design (https://github.com/neotron-compute/neotron-pico)

What is included?

You get the bare PCB, loaded with all the SMT parts. In the photo you will see that U401 is missing. This is the RGB video buffer, and JLCPCB were out of stock on the last batch. I have some spares and I will fit this part for you before shipping.

You must supply your own:

• Mornsun K7805-3AR3 PSU module
• DE15 VGA connector
• Triple 3.5mm audio jack
• CR2032 battery clip and battery
• MCP23S17 SPI I/O expander (DIP package)
• 2x 6mm push buttons
• 5x 100uF capacitors
• 22uH inductor
• PTC fuse
• SD Card slot
• DC input jack
• 4x Amphenol card-edge expansion connectors
• Raspberry Pi Pico and pins/sockets (if desired)
• DC barrel-jack PSU, 12.0V @ 1A, centre positive
• VGA monitor and VGA cable
• PS/2 keyboard
• Full-size SD Card, FAT32 formatted
• Standoffs (or a whole microATX case, if desired)

The complete parts list is available on my Github repo. All parts available from the usual catalog retailers.

What about software?

You can flash your Raspberry Pi Pico with CircuitPython and play with the hardware, or you can load it with the very incomplete and work-in-progress Neotron OS, which is open-source and also available on my Github. So far it will display some text on screen, as shown in the photos, and show a simple prompt you can use to enter commands. This is a platform for hacking on embedded software, not (yet) a finished product!

The Raspberry Pi Pico-W will also work, but I have no software support for Wi-Fi in Neotron OS at this time.

Why did you make it?

So that people had access to a modern computer built from readily available parts, but that was simple enough for one person to understand.

What makes it special?

It is perhaps the only open-source microATX form-factor computer powered by the Raspberry Pi Pico.