Open Source Hardware Board Runs Unix Like RetroBSD OS On PIC32 MCU


Olimex recently released PIC32-RETROBSD, a new development board designed specifically for the RetroBSD operating system. This open source kit includes a PIC32MX microcontroller and represents a testament to the benefits of the MIPS architecture, allowing developers to run a Unix-based, sophisticated operating system in as low as 128 KB of RAM, including a C compiler.

RetroBSD is a port of 2.11BSD Unix intended for embedded systems with fixed memory mapping. The current target is Microchip PIC32 microcontroller with 128 kbytes of RAM and 512 kbytes of Flash. PIC32 processor has MIPS M4K architecture, executable data memory and flexible RAM partitioning between user and kernel modes. The project is open source and hosted at

The RetroBSD project ( was started five years ago by Serge Vakulenko, a MIPS developer who wanted to see whether it’s technically possible to port the 16-bit 2.11BSD open source operating system to a modern PIC32MX microcontroller. It turned out this was not only perfectly possible, but the resulting system could also include a full set of drivers for GPIO, UART, SPI, LCD displays etc.


When Microchip introduced the new PIC32MZ MCU family, the same developer was able to port the much more powerful, but still compact 4.4BSD operating system to it, and kick-start the LiteBSD project.

Since the PIC32MZ MCU includes 512 KB of RAM, developers can run even more sophisticated applications using LiteBSD. Currently about 200 KB of memory is available for the user space, and due to TLB and paging support this amount can be doubled or even tripled. The LiteBSD kernel has a fully-featured networking TCP/IP stack and the Ethernet driver is ready and functional. A Wi-Fi driver for the chipKIT WiFIRE board is currently under development (presently 80 per cent of the work is complete).

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Free PIC32-RetroBSD boards are being shipped to the nine RetroBSD developers.



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