The Minimalist PC You Can Build Around a $1 Chip
PicoTop transforms the RP2350 microcontroller into a functional PC, complete with a custom OS, keyboard support, and HDMI output.
A microcontroller is, of course, a complete computer. With a processor, memory, and programmable input/output peripherals, it’s got what it takes to meet the definition. However, microcontrollers don’t really seem like computers to most of us. Where is the video output? How about an operating system and a keyboard?
A GitHub user who goes by the handle 7west has added exactly these types of conveniences to the very popular Raspberry Pi RP2350 microcontroller. An entire system, called PicoTop, was built around this computer-on-a-chip to make it feel more like a traditional computer. To make it more useful, 7west even hacked together a custom operating system for the computer from scratch.
PicoTop is a minimalist single-board computer that strips the idea of personal computing down to its essentials. The device outputs a crisp, black-and-white 640×480 terminal over HDMI using the RP2350’s HSTX interface, delivering DVI-compatible video through a standard HDMI connector. Input is handled through a USB-A port for a keyboard, giving the system a familiar, no-frills interface reminiscent of early home computers.
Despite its simplicity, PicoTop includes a reasonably complete set of hardware features. A rechargeable LiPo battery with USB-C charging makes the system portable, while an onboard real-time clock keeps time even when powered off. Storage is handled via a microSD card formatted with a FAT16 file system, although only 2GB cards or smaller are supported, and filenames must adhere to the classic 8.3 format.
Designed to be entirely keyboard-driven, the operating system boots into a shell that acts as the central hub for interacting with the system. Users can navigate directories, manage files, and execute programs using familiar command-line tools like ls, cd, cp, and mv. Built-in applications include a lightweight text editor called uEdit, a calculator workbook, and even a small Hangman game — because no computing platform is complete without at least one game.
One particularly notable feature is the “Vault,” an encrypted folder system that adds a layer of data security uncommon in hobbyist microcontroller projects. Additionally, exposed GPIO, I2C, and UART pins allow PicoTop to interface with external hardware, preserving the flexibility expected from a microcontroller platform.
7west describes PicoTop as a work in progress and acknowledges that shortcuts were taken in both hardware and software design. Even so, the project demonstrates how far modern microcontrollers can be pushed with a bit of creativity. Check out the GitHub repository for more details on the build.